Getting Start With Struts

I want to do a video of IT tutorial, can you arrange the text content of the video tutorial for me according to the content of the website. Let’s start with the Struts tutorial, and you will give me a list of things to cover.

Of course! The following is an outline of Struts-based IT tutorial video series. You can make a tutorial video based on this outline.

1. Introduction to Struts 1.1. What is Struts 1.2. History and development of Struts 1.3. Advantages and application scenarios of Struts
2. Struts Core Components 2.1. ActionServlet 2.2. Configuration file (struts-config.xml) 2.3. Form Bean(ActionForm) 2.4. Business Logic Processing (Action) 2.5. View (JSP)
3. Setting up the Struts development environment 3.1. JDK Installation and Configuration 3.2. Eclipse IDE Installation and Configuration 3.3. Tomcat Server Installation and Configuration 3.4. Download and import of Struts library files
4. The first Struts program 4.1. Create a simple Struts project 4.2. Writing the ActionForm class 4.3. Writing the Action Class 4.4. Writing JSP Pages 4.5. Configuring struts-config.xml 4.6. Compile, deploy, and test
5. Struts Form Validation 5.1. Introduction to Struts’ built-in validation framework 5.2. Writing Validators 5.3. Configuring the validation rule file (validation.xml) 5.4. Internationalization of error messages
6. Struts Tag Library 6.1. Introduction to the Struts Tag Library 6.2. Examples of the use of common Struts tags 6.3. Customize Struts labels
7. Struts Interceptor 7.1. Introduction to Interceptors 7.2. Writing Custom Interceptors 7.3. Configure the interceptor chain
8. Struts and Ajax 8.1. Introduction to Ajax 8.2. Integration of Struts with Ajax 8.3. Implement an Ajax example
9. Case in action: A simple CRUD application 9.1. Project Requirements Analysis 9.2. Database Design and Construction 9.3. Implementing ActionForm, Action, and JSP Pages 9.4. Implementing the Data Access Layer (DAO) 9.5. Implement the business logic layer (Service)
10. Best Practices for Struts 10.1. Project structure and naming conventions 10.2. Performance Tuning Recommendations 10.3. Security recommendations

Hopefully, this content outline will help you produce high-quality Struts tutorial videos. If you have any

Please explain in detail what Struts is

Struts is an open source Java web application framework maintained and developed by the Apache Software Foundation. It adopts the MVC (Model-View-Controller) design pattern to simplify the development and maintenance of web applications. The Struts framework helps developers quickly build scalable, maintainable web applications by providing a set of feature-rich components and tag libraries.

Three components of the MVC design pattern are embodied in the Struts framework:

1. Model: A model represents the business logic and data of the application. In Struts, a model typically consists of a JavaBean, a POJO (Plain Old Java Object), and a database access layer.
2. View: The view is responsible for presenting data to the user. In Struts, views are usually implemented by front-end technologies such as JSP (JavaServer Pages) pages, HTML, CSS, and JavaScript.
3. Controller: The controller is responsible for processing user requests and updating the model. In Struts, a controller consists of an ActionServlet and an Action class. The ActionServlet receives the user’s request, distributes the request to the appropriate Action class, which processes the request and updates the model, and finally returns the processing results to the view.

Key features of Struts:

1. The MVC design pattern is adopted, which is conducive to the layering and modularization of the code, and improves the maintainability and extensibility of the code.
2. Provides a rich tag library that simplifies JSP page development.
3. Support form validation, internationalization, error handling and other functions, convenient for developers to implement high-quality web applications.
4. With good community support and documentation, it is easy for developers to learn and use.

In summary, Struts is a feature-rich, easy-to-use Java web application framework for building web projects of all sizes.

Please explain in detail the history and development of Struts

The history and development of the Struts framework can be divided into the following stages:

1. The Struts framework was originally created by Craig R. McClanahan in 2000. At the time, Java web applications were relatively complex to develop and maintain, lacking uniform design patterns and specifications. Craig R. McClanahan was inspired by the MVC design pattern to create the Struts framework, which aims to simplify the development process of Java web applications.
2. Growth stage: In 2001, the Struts project was officially adopted into the Apache Jakarta project and began to receive more attention and use. In 2002, Apache Struts 1.0 was released, becoming the popular Java web application framework at the time. Subsequently, Struts continued to iterate on versions, introducing more new features, such as form validation, internationalization, tag libraries, etc., and gradually became the industry standard for Java web development.
3. Transformation phase: In 2004, the development team of the WebWork framework merged with the Struts team to develop a new Java EE-based web application framework. This new framework, called Struts 2, retains some of the core concepts of Struts 1 while introducing WebWork’s excellent features such as interceptors, OGNL expressions, and more. In 2007, Struts 2.0 was officially released, becoming the next generation of the Struts family.
4. Steady development: Over the past decade or so, the Struts 2 framework has been continuously updated and optimized, providing more new features and improvements. While other Java web frameworks such as Spring MVC and JavaServer Faces have risen and gained market share during this period, Struts 2 is still widely used in many enterprises and projects.

Summary: The history and development of the Struts Framework has gone through stages of creation, growth, transformation and stable development. From Struts 1 to Struts 2, it has been an important framework for Java web application development. Although there are many other Java web frameworks on the market today, Struts still has some competitiveness and influence.

Please explain in detail the advantages and application scenarios of Struts

The Struts framework has certain advantages in web application development, here are some of the main advantages:

1. MVC design pattern: Struts adopts the Model-View-Controller (MVC) design pattern, which is conducive to the layering and modularity of code, and improves the maintainability and extensibility of code. By separating business logic, data presentation, and user request processing, Struts makes it easier for developers to maintain and extend projects.
2. Rich tag library: Struts provides a rich tag library, including HTML tags, bean tags, logical tags, etc. These tags simplify the development of JSP pages and enable developers to write view layer code more efficiently.
3. Form validation and internationalization support: Struts has a built-in form validation framework that allows developers to easily add validation rules to forms. In addition, Struts provides internationalization support for developers building multilingual web applications.
4. Extensibility: Struts is well extensible and can extend the framework functionality with plugins, custom interceptors, custom labels, etc. This allows Struts to adapt to a variety of complex application scenarios.
5. Community support: Struts has a large developer community and rich documentation resources, making it easier for developers to learn and use the Struts framework. At the same time, since Struts is a mature framework, it is easy to find solutions in the community when encountering problems.

Application scenarios:

The Struts framework is suitable for the following application scenarios:

1. Enterprise Web Applications: The Struts framework is ideal for building enterprise web applications because it provides a mature set of solutions and tools, including data validation, internationalization, error handling, and more. In addition, the MVC design pattern can improve the maintainability and extensibility of the code.
2. Education & Training: Because Struts has extensive documentation and community support, it is also suitable for education and training environments. Learners can master the basic principles and skills of Java web development by learning the Struts framework.
3. Small and medium-sized web projects: The Struts framework is suitable for web projects of all sizes. For small and medium-sized web projects, Struts can provide a rapid development solution to reduce the difficulty of development.

Although Struts may not be as good as other modern frameworks (such as Spring MVC) in some ways, it is still a feature

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Powerful, mature Java web application framework with a certain degree of competitiveness. Here’s how Struts performs in other use cases:

4. Integration with other frameworks: Struts can integrate with other Java technologies and frameworks such as Hibernate, Spring, MyBatis, etc. This allows developers to take full advantage of these frameworks to build more complex and performant web applications.
5. Adapt to changing needs: Thanks to Struts’ scalability and flexibility, it can adapt to changing business needs. Developers can customize and extend the Struts framework according to project requirements to meet different application scenarios.
6. Large Projects and Distributed Systems: The Struts framework can support the development of large projects and distributed systems. Through the MVC design pattern, developers can separate business logic, data processing, and user interface, which is conducive to team collaborative development and project management. At the same time, Struts’ integration capabilities with other frameworks also help build high-performance, high-availability distributed systems.

In summary, although the Struts framework may not be as good as other modern frameworks in some ways, it is still competitive in many application scenarios. The Struts framework helps developers quickly build scalable, maintainable web applications and integrates seamlessly with other Java technologies and frameworks, providing a complete Java web development solution.

Please explain in detail the Struts Core Components Controller (ActionServlet)

In the Struts framework, the controller is the core component responsible for handling user requests and coordinating models and views. The ActionServlet is the main controller component in Struts, which acts as a central scheduler, responsible for receiving user requests, distributing them to the appropriate Action class, and returning the processing results to the view layer.

Here are the main responsibilities and workflows of ActionServlet:

1. Initialization: When the web application starts, the ActionServlet automatically initializes. During initialization, it reads the Struts configuration file (usually struts-config.xml), loads the Action maps, form beans, global exception handling, and other information defined in it, and stores this information in an internal data structure for subsequent use.
2. Request handling: When a user initiates a request, the request first arrives at the ActionServlet. As the central dispatcher, the ActionServlet is responsible for parsing the request and identifying the target Action class of the request. It then creates an Action object, prepares all the necessary request parameters and data, and delegates the request to the Action object for processing.
3. Action execution: After the Action object receives the request, it executes the corresponding business logic. This may include interacting with a model layer, such as a database access layer, to get or update data. After processing the request, the Action object returns a string that represents the result of the processing, often called “ActionForward” or “ActionResult”.
4. Result distribution: Based on the ActionResult returned by the Action object, the ActionServlet looks for the corresponding view page (such as a JSP file). It then forwards the request to the appropriate view page so that the view page can display the processing results to the user.
5. Error handling: During request handling, if an exception occurs, ActionServlet forwards the exception to the appropriate error-handling page or handling class according to the global exception handling rules defined in the Struts configuration file. In this way, developers can focus on handling errors and exceptions, improving the maintainability of the code.

In summary, ActionServlets are the core controller components in the Struts framework, which are responsible for receiving user requests, dispatching Action classes, distributing processing results, and handling errors and exceptions. By using ActionServlets, developers can implement request processing logic for web applications, simplifying the development process and improving code quality.

Please explain in detail the Struts Core Components configuration file (struts-config.xml)

The core configuration file of the Struts framework (often named struts-config.xml) is an XML file that defines and configures various components of a Struts application, such as Action maps, form beans, global exception handling, and so on. This configuration file is loaded at application startup, providing Struts with the information it needs to run. In the Struts framework, the struts-config .xml file plays a crucial role, allowing developers to centrally manage and control the behavior of the entire application.

Here are the main elements in the struts-config .xml configuration file:

1. Action-mappings: This element contains one or more action elements that define the mapping between the request path and the Action class. Each action element contains a path, an Action class, and one or more forward elements that define the mapping between the result of the request (e.g. success, failure, etc.) and the view page.
2. form-beans: This element contains one or more form-bean elements that define the form bean. A form bean is usually a JavaBean that encapsulates form data. Each form-bean element contains a name and a corresponding Java class.
3. global-exceptions: This element contains one or more exception elements that define global exception handling rules. Each exception element contains an exception type and a corresponding error handling page (path) or handler.
4. global-forwards: This element contains one or more forward elements that define global view jump rules. Each forward element contains a name and a corresponding view page (path).
5. message-resources: This element is used to define the location of internationalized resource files. By referencing resource files in different languages, the Struts framework can achieve multilingual support.
6. plug-ins: This element contains one or more plug-in elements that define the plugins required by the Struts application. Each plug-in element contains a corresponding Java class (className).

In summary, the struts-config.xml configuration file is the core configuration file of the Struts framework, which defines and configures the various components of a Struts application. By modifying and tweaking this file, developers can easily centrally manage and control the behavior of the entire application.

Please explain in detail the Struts Core Components Form Bean (ActionForm)

In the Struts framework, form beans (usually inherited from the ActionForm class) are Java classes used to encapsulate and process form data submitted by users. A form bean is usually a simple JavaBean with a set of properties and corresponding getter and setter methods. By using form beans, developers can decouple form data from specific processing logic (such as the Action class) to improve the readability and maintainability of code.

Here are the key features and functionality of form beans:

1. Data encapsulation: Form beans are responsible for encapsulating form data submitted by users. The properties of each form bean typically correspond to an input field in the form. When the user submits the form, the Struts framework automatically populates the form data into the corresponding form bean.
2. Data conversion: Form beans can convert form data submitted by the user to the appropriate Java data type. For example, convert form data of type string to integers, dates, and so on. This makes it easier for developers to process and validate form data.
3. Data validation: Form beans can contain validation logic that checks that the form data submitted by the user conforms to the expected format and constraints. For example, check if an input field is empty or if a number is within a specified range. Developers can implement these validation logic in the validate() method of the form bean. If the form data fails validation, the Struts framework returns an error message to the user and displays an appropriate error message.
4. Decoupling from the Action class: Form beans are decoupled from concrete processing logic (such as the Action class). This means that developers can change or replace the Action class without modifying the form bean. This separation helps improve the readability and maintainability of the code.
5. Reuse and sharing: Since form beans are independent Java classes, they can be reused and shared across multiple Action classes. This allows developers to work with similar form data more efficiently.

In summary, form beans (usually inherited from the ActionForm class) are the core components of the Struts framework for encapsulating and processing user-submitted form data. By using form beans, developers can decouple form data from specific processing logic, improve the readability and maintainability of code, and implement data validation and transformation functions.

Please explain in detail the Struts core component Business Logic Processing (Action)

In the Struts framework, business logic processing components are typically implemented by the Action class. The Action class is a key part of the Struts application that processes user requests, executes business logic, and returns processing results. The Action class usually inherits from the org.apache.struts.action.Action base class and implements the execute() method to perform the appropriate action when the request arrives.

Here are the main responsibilities and functions of the Action class:

1. Handling user requests: When a user initiates a request, the request first arrives at the ActionServlet and then maps to the corresponding Action class based on the path of the request. The Action class is responsible for processing user requests and executing the appropriate business logic depending on the type of request.
2. Interacting with form beans: The Action class usually needs to access form data submitted by the user. In the Struts framework, form data is encapsulated in form beans. The Action class can get and manipulate form data by accessing the properties and methods of the form bean.
3. Interaction with the model layer: The Action class usually needs to interact with the model layer of the application (such as the database access layer, business logic layer, and so on) to get or update data. By interacting with the model layer, the Action class implements concrete business logic.
4. Return processing result: After processing the request, the Action class needs to return a string (often called “ActionForward” or “ActionResult”) that represents the result of processing. This string is mapped to the view pages defined in the Struts configuration file and is used to tell the ActionServlet which view page the request should be forwarded to.
5. Error handling: During the processing of a request, if an exception occurs, the Action class can throw an org.apache.struts.action.ActionError or org.apache.struts.action.ActionErrors instance. These error messages are captured by the Struts framework and returned to the user to display the appropriate error message.

In summary, the Action class is the core component of the Struts framework that processes user requests, executes business logic, and returns processing results. By implementing the Action class, developers can implement the request handling logic of the web application, interact with the form bean and model layer, and handle errors and exceptions.

Please explain in detail the Struts Core Components View (JSP)

In the Struts framework, the view layer is responsible for rendering data and the user interface, usually implemented using JavaServer Pages (JSP) technology. JSP is a Java-based server-side scripting language that allows developers to embed Java code in HTML or XML pages to generate and display dynamic content. By using JSPs, the Struts framework can provide a rich, interactive user interface and interact with Action classes and form beans.

Here are the main features and capabilities of using JSP as a view layer in the Struts framework:

1. Dynamic content generation: By embedding elements such as Java code, expressions, and custom tags in JSP pages, developers can generate and display dynamic content. This allows the view layer to present different content and interfaces based on user requests and changes in application state.
2. Interacting with Action classes and form beans: JSP pages can access data and methods in Action classes and form beans. By using custom tags (such as struts-tags) provided by the Struts framework, developers can easily fetch and display this data in JSP pages and trigger the corresponding processing logic.
3. Form Processing: JSP pages can be used to create and process user forms. By using the form tags provided by the Struts framework (such as <form>, <input>, etc.), developers can easily build forms and submit form data to the appropriate Action classes and form beans for processing.
4. Error Messages and Internationalization: JSP pages can display error messages and internationalization information by using custom tags provided by the Struts framework. For example, use the struts:errors tag to display error messages thrown by the Action class, and use the struts:text tag to display strings from internationalized resource files.
5. Templates and layouts: Using JSP technology, developers can create reusable templates and layouts that simplify page design and maintenance. For example, by using JSP’s include directive and custom tag library, developers can abstract common page elements (such as headers, footers, etc.) into separate templates that can then be referenced in other pages.

In summary, JSPs, as view layer components in the Struts framework, are responsible for rendering data and the user interface, and interacting with Action classes and form beans. By using JSP technology, developers can generate and present dynamic content, simplify form handling and error messages, and create reusable templates and layouts.

Please explain in detail the installation and configuration of the JDK for the Struts development environment

To set up the Struts development environment, you first need to install and configure the Java Development Kit (JDK). The following are detailed steps for installing and configuring the JDK:

1. Download JDK: Visit Oracle’s official website (https://www.oracle.com/java/technologies/javase-downloads.html) to download the latest version of the JDK installation package. Choose the appropriate installation package based on your operating system, such as Windows, macOS, or Linux. Note that the Struts framework requires Java version 1.8 or later.
2. Install the JDK: After the download is complete, double-click the installation package and follow the prompts to install it. During installation, you can choose the installation path of the JDK or use the default path. Once the installation is complete, the JDK will be installed in a folder named “jdk-version number”.
3. Configure environment variables: In order for the operating system to find the JDK’s executable files (such as javac and java), environment variables need to be configured. The following are the configuration methods for different operating systems:
   • Windows：
     1. Find the path where the JDK is installed, for example: C:\Program Files\Java\jdk-version number.
     2. Right-click Computer (or This PC), select Properties, and click Advanced System Settings.
     3. In the System Properties window, click the Environment Variables button.
     4. In the “System Variables” section, find the variable named “Path” and click the “Edit” button.
     5. In the value of the “Path” variable, add the path to the bin folder of the JDK, for example: C:\Program Files\Java\jdk-Version Number\bin. Make sure to use semicolons (; ) separation.
     6. Click OK to save the changes.
   • macOS:
     1. Open the bash configuration file by entering the following command in the terminal:.nano ~/.bash_profile
     2. Add the following at the end of the file (replace “your_path_to_jdk” with the actual JDK installation path): bashCopy codeexport JAVA_HOME=your_path_to_jdk export PATH=$JAVA_HOME/bin:$PATH
     3. Press “Control+X” to exit, then press “Y” to save the changes. Finally, enter for the changes to take effect.source ~/.bash_profile
   • Linux：
     1. Open the bash configuration file by entering the following command in the terminal:.nano ~/.bashrc
     2. Add the following at the end of the file (replace “your_path_to_jdk” with the actual JDK installation path): bashCopy codeexport JAVA_HOME=your_path_to_jdk export PATH=$JAVA_HOME/bin:$PATH
     3. Press “Control+X” to exit, then press “Y” to save the changes. Finally, enter for the changes to take effect.source ~/.bashrc
4. Verify JDK installation: To verify that the JDK is installed and configured correctly, enter the following in the command prompt or terminal

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Command:

Copy codejava -version

And:

Copy codejavac -version

If these commands correctly display Java and Javac version information, the JDK has been successfully installed and configured. For example, the output might look like this:

scssCopy codejava version "1.8.0_301"
Java(TM) SE Runtime Environment (build 1.8.0_301-b09)
Java HotSpot(TM) 64-Bit Server VM (build 25.301-b09, mixed mode)

Copy codejavac 1.8.0_301

After completing the above steps, you have successfully installed and configured the JDK. Next, you can set up the Struts development environment, install the required libraries and tools (such as Apache Tomcat server, IDE, etc.), and start developing web applications based on the Struts framework.

Please explain in detail the installation and configuration of the Eclipse IDE for the Struts development environment

The Eclipse IDE is a popular and powerful integrated development environment widely used in Java and other programming languages. To install and configure the Eclipse IDE in the Struts development environment, follow these steps:

1. Download Eclipse IDE: Visit the official Eclipse website (https://www.eclipse.org/downloads/) to download the latest version of the Eclipse IDE installation package. Choose the version that matches your operating system (such as Windows, macOS, or Linux) and system architecture (32-bit or 64-bit).
2. To install the Eclipse IDE:
   • Windows and Linux: Extract the downloaded installation package to the appropriate folder. Double-click “eclipse.exe” (Windows) or “eclipse” (Linux) in the extracted folder to start Eclipse.
   • macOS: Unzip the downloaded installation package and drag and drop the Eclipse.app into the Applications folder. Start Eclipse by double-clicking Eclipse.app.
3. Configure the Eclipse IDE: The first time you start Eclipse, it will ask you to select a workspace. A workspace is a folder that stores your project files and configuration information. Select a suitable location for your workspace and click Start.
4. Install Web Tools Platform (WTP): To develop Struts-based web applications in Eclipse, you need to install Web Tools Platform (WTP). WTP is a set of tools and plugins used to support the development of web applications. Follow these steps to install WTP:
   1. In the Eclipse menu bar, choose Help > Install New Software….
   2. In the Available Software window, select Official Eclipse Update Site (usually a URL similar to http://download.eclipse.org/releases/ Version Number) from the Work with drop-down list.
   3. In the list below, expand the Web, XML, Java EE and OSGi Enterprise Development category.
   4. Select the Eclipse Java EE Developer Tools and Eclipse Java Web Developer Tools check boxes, and then click Next.
   5. Follow the prompts to complete the installation process. After the installation is complete, restart Eclipse.
5. Configure an Apache Tomcat server: To run and debug Struts applications in Eclipse, you need to configure a web server, such as Apache Tomcat. Please download and install Apache Tomcat from the official website (https://tomcat.apache.org/). Then follow these steps to configure Tomcat in Eclipse:
   1. In the Eclipse menu bar, choose Window> Preferences (Eclipse> Preferences in macOS).
   2. In the Preferences window, expand Servers > Runtime Environment, and then click the Add button. 3

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3. In the Add Server Runtime Environment window, select the version of Apache Tomcat (that matches the version you installed) and click Next.
4. Browse to the directory where Apache Tomcat is installed and click Finish.
5. In the Preferences window, tap the Apply and OK buttons to save the settings.
6. Create a Struts project: Now that you have configured the Eclipse IDE, you can start creating a Struts-based web application project. Follow these steps:
   1. In the Eclipse menu bar, choose File> New> Other….
   2. In the New window, expand the Web category, select Dynamic Web Project, and then click Next.
   3. Enter the project name, select the target runtime (i.e. the Apache Tomcat server configured earlier), and make sure the dynamic web module version is compatible with your Struts version (usually choose 2.5 or later).
   4. Follow the prompts to complete the project creation process.
7. Add Struts libraries: To use the Struts framework in your project, you need to add the Struts libraries (JAR files) to your project’s classpath. The required JAR files can be downloaded from the official Struts website (https://struts.apache.org/download.html), or dependencies can be managed using build tools such as Maven or Gradle.
   1. Right-click the project name in Eclipse and select Properties.
   2. In the Properties window, select Java Build Path and click the Libraries tab.
   3. Click the “Add External JAR” button, browse to the folder containing the Struts library, select all JAR files, and click “Open”.
   4. In the Properties window, click the Apply and OK buttons to save the settings.

Now that you have successfully installed and configured the Eclipse IDE, you are ready to start developing web applications based on the Struts framework. When you create a project, make sure to add the Struts library to the project’s classpath in order to use Struts’ features. At the same time, configure the Apache Tomcat server to easily run and debug your application in Eclipse.

Please explain in detail the installation and configuration of the Tomcat server for the Struts development environment

Apache Tomcat Server is a popular open source web server for deploying Java web applications. The following are detailed explanations of the steps for installing and configuring the Apache Tomcat server:

1. Download Apache Tomcat: Visit the official Apache Tomcat website (https://tomcat.apache.org/) and choose the version of Tomcat that matches your needs and development environment. Typically, choose the latest stable version (such as Tomcat 9 or Tomcat 10). Download the corresponding version of the binary distribution, such as zip (Windows) or tar.gz (macOS and Linux) files.
2. Install Apache Tomcat: Unzip the downloaded package to a suitable location. The extracted folder is the Tomcat installation directory. Note this path, which will be used for subsequent configurations.
3. Configure environment variables (optional): To conveniently start and stop the Tomcat server from the command line, you can add Tomcat’s bin directory to the system’s PATH environment variable. For more information, see the previous section on configuring environment variables in the JDK. For Tomcat, its bin directory path needs to be added to the system’s PATH environment variable.
4. Test the Tomcat server: Start the Tomcat server to test that it is installed correctly.
   • Windows: Double-click the “startup.bat” file in the bin folder under the installation directory.
   • macOS and Linux: In the terminal, navigate to the bin folder under the installation directory and run the command../startup.sh
   After successful launch, using a web browser, you should see the Apache Tomcat welcome page. To stop the Tomcat server, run the appropriate “shutdown.bat” (Windows) or (macOS and Linux) script.http://localhost:8080./shutdown.sh
5. Configure the Tomcat server in Eclipse: To configure the Tomcat server in the Eclipse IDE, refer to the “Configuring the Apache Tomcat Server” section in the previous answer.

After completing the above steps, you have successfully installed and configured the Apache Tomcat server. Next, you can use the Eclipse IDE to develop, deploy, and run web applications based on the Struts framework.

Please explain in detail how to create a simple Struts project

To create a simple Struts-based web application project, you can follow these steps:

1. Configure the development environment: Make sure that the JDK, Eclipse IDE, and Apache Tomcat server are installed and configured. These steps have been explained in detail in the previous answers.
2. Create a new dynamic web project:
   • Open the Eclipse IDE and click File> New> Other….
   • In the New dialog box, expand the Web category, select Dynamic Web Project, and then click Next.
   • Enter a name for the project, select the previously configured target runtime (Apache Tomcat server), and make sure the dynamic web module version is compatible with your Struts version (usually choose 2.5 or later).
   • Follow the prompts to complete the project creation process.
3. Add Struts libraries: Download the required JAR files from the official Struts website (https://struts.apache.org/download.html), or manage dependencies using build tools like Maven or Gradle. Add these JAR files to the project’s classpath:
   • Right-click the project name in Eclipse and select Properties.
   • In the Properties window, select Java Build Path and click the Libraries tab.
   • Click the “Add External JAR” button, browse to the folder containing the Struts library, select all JAR files, and click “Open”.
   • In the Properties window, click the Apply and OK buttons to save the settings.
4. To create the Struts core components:
   • ActionForm: Create a Java class in the src directory, inheriting org.apache.struts.action.ActionForm.
   • Action: Create a Java class in the src directory, inheriting org.apache.struts.action.Action. Override the execute() method to handle the business logic.
   • JSP View: Create a new JSP file in the WebContent directory to display the results.
5. Configure struts-config .xml: Create a file called struts-config.xml in the WEB-INF directory to configure the core components of Struts. In this file, define ActionForms, Actions, and the mapping relationships between them.
6. Configure web.xml: In the web.xml file in the WEB-INF directory, configure the path to the Struts core controller ActionServlet and the struts-config .xml.
7. To deploy and run the project:
   • In Eclipse, right-click the project and select Run As> Run on Server.
   • In the dialog box that appears, select the Apache Tomcat server that you configured earlier and click Finish.
   • Eclipse will deploy and launch the project, and a web browser will automatically open the project’s homepage.

After the above steps, you will have successfully created and run a simple Struts-based web application project. During the actual development process, you need to customize and expand accordingly according to the needs of your project.

Please explain in detail how to write the ActionForm class

ActionFormThe Struts class is a core component in the Struts framework that encapsulates and processes data from forms. When you write a class, you need to inherit the class and create the corresponding properties and getter/setter methods for each field in the form.ActionFormorg.apache.struts.action.ActionForm

Here are the steps to write a class:ActionForm

1. In the Eclipse IDE project, create a new Java class in the directory. For example, create a class named .srcMyForm
2. Modify the class so that it inherits the class. Import the necessary packages () to resolve the class name reference problem.MyFormorg.apache.struts.action.ActionFormorg.apache.struts.action.ActionForm
3. Create appropriate properties for each field in the form. For example, if your form contains an input box named Enterbox, create a property named One named in the class.usernameMyFormusername
4. Getter and setter methods are generated for each property. In Eclipse, these methods can be automatically generated by right-clicking the code editor, selecting Source > Generate getters and setters…. These methods are used to pass data between forms and Java classes.
5. Optionally, override methods to implement custom form validation logic. The Validate method returns an object that contains all errors found during validation. If no errors are found, an empty object is returned. You can use methods to add custom error information.validate()validate()org.apache.struts.action.ActionErrorsActionErrorsaddError()

Here’s a simple class example:ActionForm

javaCopy codeimport org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionError;

public class MyForm extends ActionForm {
    private String username;
    private String email;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public ActionErrors validate(org.apache.struts.action.ActionMapping mapping, javax.servlet.http.HttpServletRequest request) {
        ActionErrors errors = new ActionErrors();
        if (username == null || username.trim().isEmpty()) {
            errors.add("username", new ActionError("error.username.required"));
        }
        if (email == null || email.trim().isEmpty()) {
            errors.add("email", new ActionError("error.email.required"));
        }
        return errors;
    }
}

In this example, we define two properties: and generate getter and setter methods for these two properties. We’ve also overridden methods to ensure that the AND field is not empty. If an error is found, the appropriate error information is added to the object.usernameemailvalidate()usernameemailActionErrors

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Next, we’ll discuss how to interact with other Struts framework components using the class we just created.ActionForm

1. Create a JSP form page: Create a new JSP file under the directory, such as. Create a form in this page and associate it to a class using tags. In order to use tags, you need to import the Struts tag library, add the following code to the top of the JSP page: jspCopy code creates a form as follows: jspCopy code In the example above, we create a form with tags and set its properties to. We also created two input boxes with labels and set their properties to and respectively. These properties are bound to the corresponding properties in the class.WebContentindex.jsp<html:form>ActionForm<html:form><%@ taglib uri="http://struts.apache.org/tags-html" prefix="html" %> <html:form action="/submitForm"> <table> <tr> <td>Username:</td> <td><html:text property="username" /></td> </tr> <tr> <td>Email:</td> <td><html:text property="email" /></td> </tr> <tr> <td colspan="2" align="center"> <html:submit value="Submit" /> </td> </tr> </table> </html:form> <html:form>action/submitForm<html:text>propertyusernameemailActionForm
2. Create a class: Create a new Java class in the directory, such as. Make it inherit the class and override the method. In the method, you can use the object to get the data submitted by the form and handle the corresponding business logic. For example: javaCopy codeActionsrcMyActionorg.apache.struts.action.Actionexecute()execute()ActionFormimport org.apache.struts.action.Action; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; public class MyAction extends Action { @Override public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) { MyForm myForm = (MyForm) form; String username = myForm.getUsername(); String email = myForm.getEmail(); // 处理业务逻辑，如将数据存储到数据库或发送电子邮件等。 return mapping.findForward("success"); } }
3. Profile: Create or edit files under a directory. Map classes to the appropriate paths. For example: xmlCopy codestruts-config.xmlWEB-INFstruts-config.xmlActionFormAction<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.3//EN" "http://struts.apache.org/dtds/struts-config_1_3.dtd"> <struts-config> <form-beans> <form-bean name="myForm" type="com.example.MyForm" />

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phpCopy code   </form-beans>
   <action-mappings>
       <action path="/submitForm" type="com.example.MyAction" name="myForm" scope="request" validate="true" input="/index.jsp">
           <forward name="success" path="/success.jsp" />
       </action>
   </action-mappings>

</struts-config> “`

In the example above, we first defined the class in the section, and then defined a mapping for the path in the section. This mapping associates the class with the class and sets form validation to. If validation fails, it is returned to the page specified by the property. If the method returns success, it is forwarded to the page.<form-beans>MyForm<action-mappings>/submitFormActionMyActionMyFormtrueinput/index.jspexecute()/success.jsp

4. Configuration file: In the file in the directory, configure the path of the Struts core controller and it. For example: xmlCopy code In this example, we define a servlet for the Struts core controller and associate it with the URL pattern. We also specify the location of the file.web.xmlWEB-INFweb.xmlActionServletstruts-config.xml<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0"> <display-name>StrutsExample</display-name> <servlet> <servlet-name>action</servlet-name> <servlet-class>org.apache.struts.action.ActionServlet</servlet-class> <init-param> <param-name>config</param-name> <param-value>/WEB-INF/struts-config.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>action</servlet-name> <url-pattern>*.do</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app> ActionServlet*.dostruts-config.xml
5. Create Success Page: Create a new JSP page, such as a message that displays the success of the operation. For example: jspCopy codesuccess.jsp<!DOCTYPE html> <html> <head> <title>Success</title> </head> <body> <h1>Form submitted successfully!</h1> </body> </html>
6. Deploy and run the project: In Eclipse, right-click the project and select Run As> Run on Server. Select the Apache Tomcat server you configured earlier and click Finish. Eclipse will deploy and launch the project, and a web browser will automatically open the project’s homepage.

After the above steps, you have created a simple Struts application, where:

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Includes a JSP page that submits the form, a class to process form data, a class to handle business logic, and a success page. When the user enters data on the page and submits the form, the Struts framework encapsulates the form data into a class and passes it to the class. The class then processes the business logic and returns the appropriate view.ActionFormActionindex.jspActionFormActionAction

Next, you can move on to explore more features of the Struts framework, such as:

1. Use labels to display form validation error messages.<html:errors>
2. Use internationalization support to create multilingual applications.
3. Use the Struts layout tag library (, , , etc.) to create complex page layouts.<html:table><html:row><html:cell>
4. Use the Struts logic tag library (, , etc.) to add conditional and circular logic to JSP pages.<logic:iterate><logic:equal>
5. Use Struts plugins (e.g. Tiles plugins, Validator plugins, etc.) to extend framework functionality.
6. Use Struts to integrate with other Java EE technologies such as JDBC, JPA, EJB, Spring, etc. to build more complex web applications.

By learning and practicing these advanced features, you will better understand the Struts framework and be able to use its strengths in real-world projects.

Please explain in detail how to write the Action class

ActionClasses are one of the core components of the Struts framework and are used to handle business logic from user requests. When you write a class, you need to inherit the class and override the methods. The method receives the following parameters:Actionorg.apache.struts.action.Actionexecute()execute()

1. ActionMapping: The current mapping information, including paths, names, etc.ActionAction
2. ActionForm: A form bean that encapsulates data from the form submission.
3. HttpServletRequest: Represents the HTTP information requested by the user.
4. HttpServletResponse: Represents the HTTP response of the application to the user’s request.

Here are the steps to write a class:Action

1. In the Eclipse IDE project, create a new Java class in the directory. For example, create a class named .srcMyAction
2. Modify the class so that it inherits the class. Import the necessary packages () to resolve the class name reference problem.MyActionorg.apache.struts.action.Actionorg.apache.struts.action.Action
3. Overriding methods. Inside this method, you can get the form data, process the business logic, and return the appropriate view. For example:execute()

javaCopy codeimport org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

public class MyAction extends Action {
    @Override
    public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) {
        MyForm myForm = (MyForm) form;
        String username = myForm.getUsername();
        String email = myForm.getEmail();

        // 处理业务逻辑，如将数据存储到数据库或发送电子邮件等。

        return mapping.findForward("success");
    }
}

In the example above, we first convert the object to a custom type. We then get the data submitted by the form (such as and fields) from the object. We can then handle the business logic based on actual needs, such as storing data in a database or sending an email. Finally, the appropriate view (for example, success page or error page) is returned based on the processing result.ActionFormMyFormMyFormusernameemail

4. Configure the class in the file. Map the class to the appropriate path and associate the appropriate form bean. For example:struts-config.xmlActionAction

xmlCopy code<action-mappings>
    <action path="/submitForm" type="com.example.MyAction" name="myForm" scope="request" validate="true" input="/index.jsp">
        <forward name="success" path="/success.jsp" />
    </action>
</action-mappings>

In the example above, we mapped the path to a class and associated it with the form bean. We also set up form validation, specify the input page to return if validation fails, and the view path when the method returns successfully./submitFormMyActionMyFormexecute()

With the above steps, you have created a simple class and learned how to interact with other Struts framework componentsAction

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Next, we’ll explore some advanced class-related topics so that you can better understand how to use them.Action

1. Dynamic method calls: By default, Struts calls methods in the class to process requests. However, you can also use the dynamic method call feature to have Struts call other methods in the class. To achieve this, you need to configure the properties in and implement the appropriate methods in the class. For example: xmlCopy code, then implement the method in the class: javaCopy codeActionexecute()Actionstruts-config.xmlActionmethodAction<action path="/submitForm" type="com.example.MyAction" method="myCustomMethod" name="myForm" scope="request" validate="true" input="/index.jsp"> <forward name="success" path="/success.jsp" /> </action> MyActionmyCustomMethod()public class MyAction extends Action { public ActionForward myCustomMethod(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) { // ... } }
2. Handling form validation errors: When form validation is enabled, Struts validates the form data before calling the class. If validation fails, Struts returns to the input page and saves the error information in the object. You can use tags on JSP pages to display error messages. For example, add the following code to the page: jspCopy code in the class, and you can also use methods to save custom error information to an object. For example: javaCopy codeActionActionErrors<html:errors>index.jsp<html:errors/> ActionsaveErrors(request, errors)ActionErrorspublic class MyAction extends Action { @Override public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) { MyForm myForm = (MyForm) form; // 检查用户名和电子邮件 if (myForm.getUsername().isEmpty() || myForm.getEmail().isEmpty()) { ActionErrors errors = new ActionErrors(); errors.add("emptyFields", new ActionMessage("error.empty.fields")); saveErrors(request, errors); return mapping.getInputForward(); } // ... } }
3. Use: In a class, you can use objects to define views to forward or redirect to. Objects can be obtained through the object’s methods, or you can create new objects directly. For example, javaCopy code to perform redirection (rather than forwarding), you need to set its property to: javaCopy code when you create the objectActionForwardActionActionForwardActionForwardActionMappingfindForward()ActionForwardpublic class MyAction extends Action { @Override public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) { // ... ActionForward successForward = mapping.findForward("success"); // 或 ActionForward successForward = new ActionForward("/success.jsp"); return successForward; } } ActionForwardredirecttrueActionForward redirectForward = new ActionForward("/success.jsp", true);

By gaining insight into classes and their related functions, you will be able to be more effectiveAction

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Use the Struts framework to handle business logic. Here are some other advanced concepts that you can apply in real projects:

4. Use and: In addition to using Save error messages, you can also use Save Success or notification messages. Similarly, you can use methods in a class to save messages to objects. On the JSP page, use the label to display the message. For example, add the following code to the page: jspCopy codeActionMessagesActionErrorsActionErrorsActionMessagesActionErrorsActionsaveMessages(request, messages)ActionMessages<html:messages>success.jsp<html:messages/>
5. Integration with other Java EE technologies: In a real project, you may need to integrate with the Struts framework using other Java EE technologies (such as JDBC, JPA, EJB, Spring, etc.). For example, you can call a Data Access Object (DAO) in a class to retrieve data from a database, or a Spring Bean to take advantage of its services. To keep the responsibility of the class single and avoid executing complex business logic directly within the class, you should delegate the business logic to other specialized service classes.ActionActionAction
6. Use interceptors: In Struts 2, you can use interceptors to pre- and post-process requests. An interceptor is a mechanism for executing logic before a request reaches a class or after the class returns a result. By using interceptors, you can implement cross-cutting concerns (such as logging, authentication, authorization, and so on) without modifying the class. To use interceptors in Struts 2, you need to implement the interface and configure the interceptor in a file.ActionActionActionInterceptorstruts.xml

By learning and practicing these advanced concepts, you will be able to better understand the Struts framework and make the most of its capabilities in real projects. Continuously improve your skills to become a stronger Java web developer.

Please explain in detail how to configure struts-config .xml

struts-config.xmlFiles are the main configuration files of the Struts framework, which define relationships between classes, form beans, views, and other components. The following are common elements and usage of configuration files:Actionstruts-config.xml

1. Create File: Create a file named in the project’s directory. Here’s an example of a simple file: xmlCopy codestruts-config.xmlWEB-INFstruts-config.xmlstruts-config.xml<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.3//EN" "http://struts.apache.org/dtds/struts-config_1_3.dtd"> <struts-config> <!-- 配置元素将在下面详细解释 --> </struts-config>
2. Configure form beans: Use elements to define form beans used in your project. Each element should contain an attribute that references the form bean in the file and an attribute that specifies the full class name of the form bean. For example: xmlCopy code<form-beans><form-bean>namestruts-config.xmltype<form-beans> <form-bean name="myForm" type="com.example.MyForm"/> </form-beans>
3. Configuration mapping: Use elements to define the classes used in the project. Each element should contain the following attributes:Action<action-mappings>Action<action>
   • path: The path used to reference the class in the URL.Action
   • type: Specifies the full class name of the class.Action
   • name: Specifies the name of the form bean associated with the class (optional).Action
   • scope: Specifies the scope (or, optionally) of the form bean.requestsession
   • validate: Specifies whether the form bean is validated (optional, default).true
   • input: Specify the input page that is returned if form validation fails (optional).
   Inside the element, use the element to define the view after the class executes. Each element should contain an attribute (used to reference the view in the class) and an attribute (specifying the JSP file path of the view). For example: xmlCopy code<action><forward>Action<forward>nameActionpath<action-mappings> <action path="/submitForm" type="com.example.MyAction" name="myForm" scope="request" validate="true" input="/index.jsp"> <forward name="success" path="/success.jsp"/> </action> </action-mappings>
4. Configure message resources: Use elements to define the message resource files used in your project. Message resource files are used to store internationalized text for applications, such as error messages, prompts, and so on. For example: xmlCopy code In the example above, the property specifies the base name of the message resource file (excluding the language code and<message-resources><message-resources parameter="com.example.messages"/> parameter

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file name extension). Assuming that the message resource file is under a package with a base name, you need to create a file named for an English environment and a file named for an Chinese environment.com.examplemessagesmessages_en.propertiesmessages_zh.properties

5. Configure plugins: Use elements to configure the Struts plugin used in your project. Plugins can extend the functionality of the Struts framework, such as providing additional tag libraries or integrating other frameworks. For example, to configure the Tiles plugin (for page layout), you need to add the following code to the file: xmlCopy code In the example above, the property specifies the full class name of the plugin class. element is used to set the properties of the plugin (in this case, the path to the Tiles definition file is specified).<plug-in>struts-config.xml<plug-in className="org.apache.struts.tiles.TilesPlugin"> <set-property property="definitions-config" value="/WEB-INF/tiles-defs.xml"/> </plug-in> className<set-property>
6. Configure other components: Files can also configure other components such as global exception handlers, global forwarding, controller properties, and so on. The following is an example of configuring the global exception handler: xmlCopy code In the example above, the property specifies the type of exception to catch, the error message key in the message resource file, and the page to display when the exception is handled.struts-config.xml<global-exceptions> <exception type="java.lang.Exception" key="error.global" path="/error.jsp"/> </global-exceptions> typekeypath

With the right profiles, you can manage and control the behavior of your entire Struts application. It is important to ensure that this file is carefully maintained during project development to better organize and manage project components.struts-config.xml

Please explain in detail the introduction to Struts’ built-in verification framework

The Struts built-in validation framework is a powerful validation mechanism that can be used to validate form data submitted by users. The framework provides a set of predefined validation rules that can easily implement common validation needs such as non-null checking, data type checking, length restrictions, and more. In addition, you can customize validation rules to meet your specific needs.

Here are the main components and usage of Struts’ built-in validation framework:

1. Validation rule file (): For each form bean that needs to be validated, you need to create a corresponding validation rule file. The naming convention for validation rule files is: form bean class name +. For example, for a form bean named , the validation rules file should be named . The validation rules file is typically located under the same package as the form bean class. The basic structure of the validation rules file is as follows: xmlCopy code*_validation.xml_validation.xmlLoginFormLoginForm_validation.xml<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE form-validation PUBLIC "-//Apache Software Foundation//DTD Commons Validator Rules Configuration 1.3.0//EN" "http://jakarta.apache.org/commons/dtds/validator_1_3_0.dtd"> <form-validation> <formset> <!-- 验证规则将在下面详细解释 --> </formset> </form-validation>
2. Configure validation rules: Inside the element, use the element to define validation rules for each attribute of the form bean. The element should contain an attribute that specifies the name of the form bean property to validate. Inside the element, use the element to define specific validation rules. For example, add non-null validation to a property of a class: xmlCopy code In the example above, the attribute specifies the validation rule type (indicating non-null validation), and the attribute of the element specifies the error message key in the message resource file.<formset><field><field>property<field><field-validator>LoginFormusername<field property="username"> <field-validator type="required"> <message key="error.username.required"/> </field-validator> </field> typerequired<message>key
3. Predefined validation rules: The Struts validation framework provides a set of predefined validation rules that can be used directly in a validation rule file. Here are some commonly used predefined validation rules:
   • required: Non-null validation
   • minlength: Minimum length verification
   • maxlength: Maximum length verification
   • email: Email format validation
   • integer: Integer validation
   • double: Floating-point number validation
   • date: Date validation
   • url: URL validation
4. Custom validation rules: If the predefined validation rules do not meet your needs, you can create custom validation rules. To create a custom validation rule, you need to perform the following steps:
   • Write a Java class that implements the interface.org.apache.struts.validator.Validator
   • In ‘commons

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The previous model used in this conversation is unavailable. We’ve switched you to the latest default model

-validator.xml file to add the configuration of custom validation rules. This file is located under the project’s classpath and is used to configure global settings and custom validation rules for the Struts validation framework. The following is an example of adding a custom validation rule:

xmlCopy code<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE validators PUBLIC "-//Apache Struts//XWork Validator Config 1.0//EN" "http://struts.apache.org/dtds/xwork-validator-config-1.0.dtd">
<validators>
    <validator name="myValidator" class="com.example.MyValidator"/>
</validators>

In the example above, the element’s attribute specifies the validation rule name, and the attribute specifies the full class name of the validation rule.<validator>nameclass

When you write a custom validation rule class, you need methods that implement the interface. The method receives a type of parameter that represents the value to be validated. In the method, you can use custom logic to validate the value and add the validation result to the object by calling the method. For example, the following is an example of a custom validation rule that checks if a user name already exists:org.apache.struts.validator.Validatorvalidate()ObjectaddValidatorResult()ValidatorActionForm

javaCopy codepublic class UsernameExistsValidator implements Validator {
    public void validate(Object object) throws ValidatorException {
        String username = (String) object;
        boolean exists = checkUsernameExists(username);
        if (exists) {
            throw new ValidatorException(new ActionMessage("error.username.exists"));
        }
    }

    private boolean checkUsernameExists(String username) {
        // 检查用户名是否已存在
    }
}

In the example above, the method uses methods to check if the user name already exists and throws an exception based on the results of the check (the exception contains an error message key that can be looked for in the message resource file).validate()checkUsernameExists()ValidatorException

When you use custom validation rules, you can reference them in the validation rule file. For example, the following is an example of using a custom validation rule:

xmlCopy code<field property="username">
    <field-validator type="myValidator">
        <message key="error.username.invalid"/>
    </field-validator>
</field>

In the example above, the attribute specifies the name of the custom validation rule, and the attribute of the element specifies the error message key.type<message>key

Form data can be easily validated using Struts’ built-in validation framework, improving the security and reliability of your application. By properly configuring validation rules, you can reduce duplicate code and errors, and better manage and maintain your project.

Please explain in detail how to write a validation rule (Validator)

In Struts, form data can be validated using validation rules to ensure the legitimacy and correctness of the data. Struts has built-in some commonly used validation rules, such as non-null validation, length validation, data type validation, etc., and custom validation rules can also be used to meet specific needs.

Here are the steps to write a Struts validation rule:

1. Create a validation rule class: To create a validation rule, you first need to create a Java class and implement the interface. The interface has only one method that executes the validation logic and returns the validation results. For example, here is a simple validation rule class that verifies that the number entered by the user is less than or equal to 10: javaCopy code In the example above, the method first takes the input number from the request parameter, then converts it to an integer and checks if it is greater than 10. If greater than 10, an error message is added with an object. If there are no errors, an empty object is returned.org.apache.struts.action.Validatorvalidate(ActionMapping, ActionForm, HttpServletRequest)public class LessThanTenValidator implements Validator { public ActionErrors validate(ActionMapping mapping, ActionForm form, HttpServletRequest request) { ActionErrors errors = new ActionErrors(); String numberString = request.getParameter("number"); int number = Integer.parseInt(numberString); if (number > 10) { errors.add("number", new ActionMessage("error.number.greaterThanTen")); } return errors; } } validate()ActionErrorsActionErrors
2. Configure validation rules: In the file, use elements to configure validation rules. For example, to configure the class created above, you can add the following code to the file: xmlCopy code In the example above, the attribute of the element specifies the full class name of the validation rule class, and the attribute specifies the validation rule name. element is used to pass parameters for validation rules, and element is used to set error messages (lookup in the message resource file or use a hard-coded string).struts-config.xml<validator>LessThanTenValidatorstruts-config.xml<form-beans> <form-bean name="myForm" type="com.example.MyForm"/> </form-beans> <global-exceptions> <exception key="error.exception" type="java.lang.Exception"/> </global-exceptions> <global-forwards> <forward name="error" path="/error.jsp"/> </global-forwards> <action-mappings> <action path="/myAction" name="myForm" type="com.example.MyAction"> <set-property property="property1" value="value1"/> <set-property property="property2" value="value2"/> <forward name="success" path="/success.jsp"/> <forward name="failure" path="/failure.jsp"/> <forward name="error" path="/error.jsp"/> <validator type="com.example.LessThanTenValidator" name="myValidator"> <param name="fieldName">number</param> <message key="error.number.greaterThanTen" resource="false"/> </validator> </action> </action-mappings> <validator>typename<param><message>
3. Validation data: When a user submits the form, validation rules are executed. If present

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Validation errors automatically go to the specified failure path (specified by the element). In the Action class, you can check for validation errors by calling the object’s methods. If there are validation errors, you can save the error message to the request object by calling the object’s methods so that the error message is displayed on the page. For example, here is an example Action class:<forward>ActionErrorsisEmpty()ActionErrorssaveErrors(HttpServletRequest)

javaCopy codepublic class MyAction extends Action {
    public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception {
        ActionErrors errors = form.validate(mapping, request);
        if (errors.isEmpty()) {
            // 处理表单数据，执行业务逻辑
            return mapping.findForward("success");
        } else {
            errors.saveErrors(request);
            return mapping.findForward("failure");
        }
    }
}

In the example above, the method is used to perform form data validation and returns an object. If the object is empty, there are no validation errors and the business logic can be executed and a success path (specified by the element) can be returned. If there are validation errors, use the method to save the error message to the request object and then return the failure path.form.validate(mapping, request)ActionErrors<forward>errors.saveErrors(request)

Struts’ validation rules can be used to easily validate form data to ensure the legitimacy and correctness of the data. By properly configuring validation rules, you can reduce duplicate code and errors, and better manage and maintain your project.

Please explain in detail how to internationalize error messages

In Struts, you can save error messages in a properties file and use the resource bundle mechanism to internationalize them so that different error messages are displayed in different locales. Here are the steps to implement internationalization error messages in Struts:

1. Create a resource package: Create a folder named in the project directory, and then create a file named in this folder to save English error messages. For example: vbnetCopy code In the above example, three English error messages are saved in the form of key-value pairs. To add error messages for other languages, create a language-related subfolder under the folder, such as (Chinese Simplified) or (French). Then create a file named under this subfolder and add the error message for the corresponding language. For example, in a file created under a folder, you can add the following: goCopy code In the example above, the same Chinese error message as the English error message is saved.srcresourcesmessages.propertieserror.required=This field is required. error.email=Invalid email address. error.length=The length of the field must be between {0} and {1}. resourceszh_CNfr_FRmessages.propertieszh_CNmessages.propertieserror.required=该字段是必需的。 error.email=无效的电子邮件地址。 error.length=字段的长度必须介于{0}和{1}之间。
2. Configure resource bundles in: In a file, use elements to configure resource bundles. For example: xmlCopy code In the example above, the property specifies the relative path to the resource bundle.struts-config.xmlstruts-config.xml<message-resources><message-resources parameter="resources.messages"/> parameter
3. Use resource bundles in the Action class: In the Action class, you can add error messages by calling the object’s methods. For example, here is a simple Action class that validates the username and password in the form: javaCopy code In the example above, if the username or password in the form is empty, the error message from the resource bundle is usedActionMessagesadd(String, ActionMessage)public class LoginAction extends Action { public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { LoginForm loginForm = (LoginForm) form; ActionErrors errors = new ActionErrors(); String username = loginForm.getUsername(); String password = loginForm.getPassword(); if (username == null || username.trim().length() == 0) { errors.add("username", new ActionMessage("error.required")); } if (password == null || password.trim().length() == 0) { errors.add("password", new ActionMessage("error.required")); } if (!authenticateUser(username, password)) { errors.add("login", new ActionMessage("error.login.invalid")); } if (errors.isEmpty()) { return mapping.findForward("success"); } else { saveErrors(request, errors); return mapping.findForward("failure"); } } private boolean authenticateUser(String username, String password) { // 身份验证逻辑 } } error.required

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Create an object and add it to the object. For example, indicates that an error message is added to the list of error messages for a field.ActionMessageActionErrorserrors.add("username", new ActionMessage("error.required"))error.requiredusername

In the example above, the method is a custom method that authenticates the user. If validation fails, an error is added to the object using the error message in the resource bundle.authenticateUsererror.login.invalidloginActionErrors

4. Display error messages in JSP page: In JSP pages, you can use tags to display all error messages. For example, here is a simple JSP page that displays error messages in a form: jspCopy code In the example above, tags are used to display all error messages. When there are error messages, they are displayed as a list, each with a separate list item.<html:errors><html:errors/> <html:form action="/login" method="post"> <html:text property="username"/> <html:text property="password"/> <html:submit/> </html:form> <html:errors>

The use of resource bundles makes it easy to implement the processing of internationalized error messages, so that applications can display different error messages in different locales. By properly configuring resource bundles and usage tags, it is convenient to display error messages in JSP pages, improving user experience and application usability.<html:errors>

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5. Use parameters in: In some cases, you may need to pass parameters into error messages in resource bundles. For example, if you want to display an error message that the length of the username should be between 5 and 20 characters, you can use the following code: javaCopy code In the example above, it is a resource pack key with two parameters, representing the minimum length and maximum length, respectively. When you add an error message, you can set these values by passing these two parameters to the object.ActionMessageserrors.add("username", new ActionMessage("error.length", 5, 20)); error.lengthActionMessage
6. Use parameters in resource bundles: In resource bundle files, you can use placeholders such as , , to indicate the location of parameters. For example, the following is an error message with parameters: goCopy code in the example above, and the position of the first and second parameters, respectively. When an error message is displayed, Struts automatically replaces these placeholders with the actual parameter values.{0}{1}error.length=The length of the field must be between {0} and {1}. {0}{1}

By using parameters, you can easily define reusable error messages in resource bundles and pass parameters to them when needed. This reduces code redundancy and errors, and improves the maintainability and reusability of the application.

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7. Extend resource bundles: In addition to configuring resource bundles in , you can create custom error messages and resource bundles through extensions and classes. For example, here is a simple custom error message class: javaCopy code In the example above, the class inherits from the class and overrides methods to implement custom error message handling logic. You can then use that class in the Action class to add custom error messages. For example, here’s an example that uses a class: javaCopy code In the example above, the class is used to create a custom error message. You can implement custom error message handling logic through override methods.struts-config.xmlActionMessagesActionMessagepublic class MyActionMessage extends ActionMessage { public MyActionMessage(String key) { super(key); } public MyActionMessage(String key, Object[] values) { super(key, values); } public String toString(Locale locale) { // 自定义错误消息的处理逻辑 } } MyActionMessageActionMessagetoString(Locale)MyActionMessagepublic class LoginAction extends Action { public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { LoginForm loginForm = (LoginForm) form; ActionErrors errors = new ActionErrors(); String username = loginForm.getUsername(); String password = loginForm.getPassword(); if (username == null || username.trim().length() == 0) { errors.add("username", new MyActionMessage("error.required")); } if (password == null || password.trim().length() == 0) { errors.add("password", new MyActionMessage("error.required")); } if (!authenticateUser(username, password)) { errors.add("login", new MyActionMessage("error.login.invalid")); } if (errors.isEmpty()) { return mapping.findForward("success"); } else { saveErrors(request, errors); return mapping.findForward("failure"); } } private boolean authenticateUser(String username, String password) { // 身份验证逻辑 } } MyActionMessagetoString(Locale)

Extensions and classes enable you to create custom error messages and resource bundles and implement custom error message handling logic. This can help applications better meet specific needs and improve application reusability and maintainability.ActionMessagesActionMessage

Please explain in detail the introduction to the Struts tag library

The Struts Tag Library is a set of JSP custom tags designed to simplify and accelerate the development of Struts web applications. The tag library provides an easy way to access model data and request processors in Struts and generate HTML form elements, links, and other web page elements. In Struts, tag libraries are one of the primary means of communication between JSP pages and Action classes.

The Struts tag library includes many different tags for different tasks. Here are some common tags in the Struts tag library and their uses:

1. <html:form>Tag tags are used to generate HTML forms, where attributes specify the Action URL submitted by the form, and attributes specify the HTTP method submitted by the form. In addition, tags provide additional properties that control the style and behavior of the form.<html:form>actionmethod<html:form>
2. <html:text>Tag tags are used to generate HTML text boxes, where attributes specify the form bean attributes associated with the text box, and attributes specify the size and maximum length of the text box.<html:text>propertysizemaxlength
3. <html:password>Tag tags are used to generate HTML password boxes, where attributes specify the form bean attributes associated with the password box, and attributes specify the size and maximum length of the password box.<html:password>propertysizemaxlength
4. <html:submit>tag tags are used to generate HTML submission buttons, where attributes specify the button’s display text.<html:submit>value
5. <html:link>Tag tags are used to generate HTML hyperlinks, where attributes specify the target Action URL of the link, attributes specify the path to the target page, and attributes specify the anchor point of the link.<html:link>actionpageanchor
6. <html:errors>The Label label is used to display error messages that result after the form is submitted, where the properties specify the form Bean property to display the error message, and the Bundle property specifies the resource bundle name to use.<html:errors>propertybundle

The Struts tag library is an important part of Struts web application development. By using tag libraries, HTML form elements, links, and other web page elements can be generated quickly and easily, reducing code redundancy and errors, and improving application maintainability and reusability.

Please explain in detail examples of the use of commonly used Struts tags

Here are a few examples of commonly used Struts tags:

1. <html:form>In the example above, tags are used to generate an HTML form for a POST request. The Propertiesproperty specifies the properties in the form bean, and the TextBox property is used to specify the size and maximum length of the text box. tags are used to generate the submit button.<html:form action="/login" method="post"> <html:text property="username" size="20" maxlength="50"/> <html:password property="password" size="20" maxlength="50"/> <html:submit value="Login"/> </html:form> <html:form>propertysizemaxlength<html:submit>
2. <html:text>In the example above, the tag is used to generate a text box, the properties specify the properties in the form bean, and the properties are used to specify the size and maximum length of the text box.<html:text property="username" size="20" maxlength="50"/> <html:text>propertysizemaxlength
3. <html:password>In the example above, the label is used to generate a password box, the properties specify the properties in the form bean, and the properties are used to specify the size and maximum length of the password box.<html:password property="password" size="20" maxlength="50"/> <html:password>propertysizemaxlength
4. <html:submit>In the example above, the label is used to generate a submit button, and the property is used to specify the button’s display text.<html:submit value="Login"/> <html:submit>value
5. <html:link>In the example above, the tag is used to generate a hyperlink, the property specifies the target Action URL of the link, the property specifies the path to the target page, and the property specifies the anchor point of the link.<html:link action="/logout" page="/index.jsp" anchor="top">Logout</html:link> <html:link>actionpageanchor
6. <html:errors>In the above example, the label is used to display the error message generated after the form is submitted, and the property specifies the form bean property to display the error message.<html:errors property="username"/> <html:errors>property

As you can see from these examples, the Struts tag library can easily generate HTML form elements, links, and other web page elements. These labels have rich properties and features and can be customized to configure as needed. By using the Struts tag library reasonably, you can speed up development, reduce the amount of code, and improve the maintainability and reusability of code.

Please explain the custom Struts tag in detail

The Struts tag library provides a lot of powerful tags that make it easy to generate various web page elements, but sometimes it may be necessary to customize some tags to meet specific needs. Custom Struts tags can be implemented by extending the label library with labels and custom label processors.

Here are the steps to customize Struts tags:

1. Create a Java class that will inherit the tag class from the tag library. The class will contain the properties and processing logic for the label. For example, here’s a custom label class: javaCopy code In the example above, the class inherits from the class and contains a custom property and processing logic.public class MyTag extends org.apache.struts.taglib.html.BaseHandlerTag { private String myAttribute; public void setMyAttribute(String myAttribute) { this.myAttribute = myAttribute; } public String getMyAttribute() { return myAttribute; } public int doStartTag() throws JspException { // 标签处理逻辑 return EVAL_BODY_INCLUDE; } } MyTagorg.apache.struts.taglib.html.BaseHandlerTagmyAttribute
2. Create a TLD file that will describe the name, attributes, and purpose of the new tag. TLD files need to contain information such as the name, description, class, attributes, and purpose of the tag. For example, here is a TLD file: xmlCopy code In the example above, the TLD file defines a new tag named and specifies the name, description, class, attributes, and purpose of the tag.<?xml version="1.0" encoding="ISO-8859-1" ?> <!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN" "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd"> <taglib> <tlib-version>1.0</tlib-version> <jsp-version>1.2</jsp-version> <short-name>mytag</short-name> <tag> <name>mytag</name> <tag-class>com.example.MyTag</tag-class> <body-content>JSP</body-content> <attribute> <name>myAttribute</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib> mytag
3. Package the TLD file and the custom tag class into a JAR file and place the JAR file in the web application’s directory.WEB-INF/lib
4. Reference the custom tag library in the JSP page and use the custom tag. For example, here’s an example of using custom labels: jspCopy code In the example above, directives are used to reference a custom tag library. Labels are used to use custom labels and pass custom attributes.<%@ taglib uri="/WEB-INF/mytag.tld" prefix="mytag" %> <mytag:mytag myAttribute="myValue"/> <%@ taglib %><mytag:mytag>myAttribute

By self

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By customizing Struts tags, you can meet specific needs and improve the efficiency and flexibility of web application development. Here are some examples of custom Struts tags:

1. Custom table label javaCopy code In the example above, the class inherits from the class and contains two custom properties and. In the tagging logic, data is presented by outputting HTML table elements.public class TableTag extends org.apache.struts.taglib.html.BaseHandlerTag { private String[] headers; private List rows; public void setHeaders(String[] headers) { this.headers = headers; } public void setRows(List rows) { this.rows = rows; } public int doStartTag() throws JspException { JspWriter out = pageContext.getOut(); try { // 输出表头 out.println("<table>"); out.println("<thead>"); out.println("<tr>"); for (String header : headers) { out.println("<th>" + header + "</th>"); } out.println("</tr>"); out.println("</thead>"); // 输出表体 out.println("<tbody>"); for (Object row : rows) { out.println("<tr>"); for (String header : headers) { String value = BeanUtils.getProperty(row, header); out.println("<td>" + value + "</td>"); } out.println("</tr>"); } out.println("</tbody>"); out.println("</table>"); } catch (Exception e) { throw new JspException(e); } return SKIP_BODY; } } TableTagorg.apache.struts.taglib.html.BaseHandlerTagheadersrows
2. Custom Pagination Tab javaCopy Code In the example above, the class inherits from the class and contains two custom properties and. In the tag processing logic, pagination is implemented by outputting an HTML link element.public class PagerTag extends org.apache.struts.taglib.html.BaseHandlerTag { private int currentPage; private int totalPages; public void setCurrentPage(int currentPage) { this.currentPage = currentPage; } public void setTotalPages(int totalPages) { this.totalPages = totalPages; } public int doStartTag() throws JspException { JspWriter out = pageContext.getOut(); try { // 输出分页链接 out.println("<div class=\"pager\">"); for (int i = 1; i <= totalPages; i++) { if (i == currentPage) { out.println("<span>" + i + "</span>"); } else { out.println("<a href=\"?page=" + i + "\">" + i + "</a>"); } } out.println("</div>"); } catch (Exception e) { throw new JspException(e); } return SKIP_BODY; } } PagerTagorg.apache.struts.taglib.html.BaseHandlerTagcurrentPagetotalPages

By customizing Struts labels, you can implement a variety of custom controls and features to speed up development and increase application flexibility.

Please explain in detail the introduction to the interceptor

Interceptor is one of the most important components in Struts2 for intercepting and handling events such as requests, responses, and exceptions. Interceptors can execute some processing logic before or after Action execution, and can be used to implement logging, permission control, exception handling, performance analysis, and other functions. Interceptors are an important part of the Struts2 framework and are key to the high flexibility and scalability of the Struts2 framework.

In Struts2, interceptors are organized through the interceptor stack, and different interceptors can be combined according to needs to form a custom interceptor stack to achieve comprehensive control and processing of requests. The interceptor stack consists of multiple interceptors arranged in a specified order, each interceptor can perform some pre-processing, post-processing, or exception handling, or terminate the processing of requests, jump to specified pages, forward requests to other actions, and so on.

Several commonly used interceptors are already built into the Struts2 framework, such as:

1. exception: Used to handle exceptions, you can catch the exceptions generated during the execution of the Action and handle them accordingly.
2. params: Used to process request parameters, you can convert request parameters into Action properties, and perform type conversion and checksum.
3. servlet-config: Used to set the configuration information of the servlet, such as Servlet Context, Request, Response, and other objects.
4. servlet-config-struts: Used to set Struts configuration information, such as Action Context, Action Proxy and other objects.
5. validation: Used to validate form data, which can be validated according to specified validation rules, and returned an error message if validation fails.

In addition to the built-in interceptors, developers can also customize interceptors to meet specific needs. Custom interceptors need to implement interfaces and override methods such as , and so on. When implementing an interceptor, you need to pay attention to the execution order of the interceptor and the configuration of the interceptor stack, ensure that the interceptor executes in the correct order, and handle all aspects of the request.com.opensymphony.xwork2.interceptor.Interceptorinit()destroy()intercept()

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In Struts2, interceptors can be combined by configuring the interceptor stack and specifying the order in which interceptors are executed. The interceptor stack consists of multiple interceptors, each with a unique name and a set of parameters, and the interceptor stack can be customized according to your needs to achieve different business needs.

The following is an example configuration of an interceptor stack:

xmlCopy code<interceptors>
   <interceptor name="myInterceptor" class="com.example.MyInterceptor">
       <param name="param1">value1</param>
       <param name="param2">value2</param>
   </interceptor>
   <interceptor-stack name="myInterceptorStack">
       <interceptor-ref name="exception"/>
       <interceptor-ref name="myInterceptor"/>
       <interceptor-ref name="params"/>
   </interceptor-stack>
</interceptors>

In the example above, a custom interceptor named is defined and two parameters are specified and . Then, an interceptor stack called one is defined and the built-in, custom, and built-in interceptors are combined, executed sequentially.myInterceptorparam1param2myInterceptorStackexceptionmyInterceptorparams

The interceptor stack can be used in Actions via annotations or XML configuration. For example, in Action, the interceptor stack used is specified by annotations:

javaCopy code@InterceptorRef("myInterceptorStack")
public class MyAction extends ActionSupport {
   // ...
}

In the example above, annotations are used to specify the use of an interceptor stack named . This way, when the action is executed, the interceptors are executed in the order in which they are in the interceptor stack and the corresponding processing is completed.@InterceptorRefmyInterceptorStack

Interceptors are one of the core components in the Struts2 framework and can be used to implement a variety of business needs. Understanding the principles and usage of interceptors can help developers better understand how the Struts2 framework works to develop more flexible and scalable web applications.

Please explain in detail how to write a custom interceptor

In Struts2, custom interceptors can be written by implementing interfaces. Interceptors are an important part of the Struts2 framework, which can intercept events such as requests, responses, and exceptions to implement various functions such as logging, permission control, exception handling, performance analysis, etc.com.opensymphony.xwork2.interceptor.Interceptor

The following is sample code for a custom interceptor:

javaCopy codepublic class MyInterceptor implements Interceptor {
   private String param1;
   private String param2;

   public void init() {
       // 初始化操作，可以在此处读取配置文件等
   }

   public void destroy() {
       // 清理资源操作，可以在此处关闭文件、网络连接等
   }

   public String intercept(ActionInvocation invocation) throws Exception {
       // 在Action执行前执行的操作
       System.out.println("param1=" + param1);
       System.out.println("param2=" + param2);

       // 调用下一个拦截器或Action
       String result = invocation.invoke();

       // 在Action执行后执行的操作
       System.out.println("result=" + result);

       return result;
   }

   public void setParam1(String param1) {
       this.param1 = param1;
   }

   public void setParam2(String param2) {
       this.param2 = param2;
   }
}

In the example above, the class implements the interface and overrides the , , and methods. In the method, the custom parameter sum is printed first, and then the method is called to proceed to the next interceptor or Action. After the action is executed, output the execution result.MyInterceptorcom.opensymphony.xwork2.interceptor.Interceptorinit()destroy()intercept()intercept()param1param2ActionInvocation.invoke()result

To use a custom interceptor, you need to configure it in the struts .xml, as shown in the following example:

xmlCopy code<interceptors>
   <interceptor name="myInterceptor" class="com.example.MyInterceptor">
       <param name="param1">value1</param>
       <param name="param2">value2</param>
   </interceptor>
</interceptors>

<action name="myAction" class="com.example.MyAction">
   <interceptor-ref name="myInterceptor"/>
   <result name="success">/success.jsp</result>
</action>

In the example above, a custom interceptor named is defined and two parameters are specified and . Then, in the configuration of Action, a custom interceptor is used to intercept and process Action requests.myInterceptorparam1param2myActionmyInterceptor

Writing a custom interceptor requires mastering the interceptor mechanism and API of the Struts2 framework, being familiar with the execution order and execution of interceptors, and how to read and handle events such as Action requests, responses, and exceptions. At the same time, it should be noted that the correctness and stability of custom interceptors have a significant impact on the operational efficiency and security of the entire application.

Please explain in detail how to configure the interceptor chain

In Struts2, the execution order and parameters of interceptors can be specified by configuring the interceptor stack to achieve processing and control of requests. The interceptor chain consists of multiple interceptors, each of which can be handled before, after, or when an exception occurs when a request is executed, and the order of the interceptor chain determines the order in which the interceptors are executed.

The following is an example configuration for an interceptor chain:

xmlCopy code<interceptors>
   <interceptor name="myInterceptor" class="com.example.MyInterceptor">
       <param name="param1">value1</param>
       <param name="param2">value2</param>
   </interceptor>

   <interceptor-stack name="myInterceptorStack">
       <interceptor-ref name="exception"/>
       <interceptor-ref name="myInterceptor"/>
       <interceptor-ref name="params"/>
   </interceptor-stack>
</interceptors>

In the example above, a custom interceptor named is defined and two parameters are specified and . Then, a chain of interceptors named one is defined and the built-in, custom, and built-in interceptors are combined, executed sequentially.myInterceptorparam1param2myInterceptorStackexceptionmyInterceptorparams

To use an interceptor chain in an Action, you can specify the name of the interceptor stack in the Action configuration or by annotating. Examples are as follows:

xmlCopy code<action name="myAction" class="com.example.MyAction">
   <interceptor-ref name="myInterceptorStack"/>
   <result name="success">/success.jsp</result>
</action>

In the example above, Action uses a chain of interceptors called to intercept and process Action requests.myActionmyInterceptorStack

Pay attention to the order of the interceptor chains, usually you need to put generic interceptors at the front of the interceptor chain to ensure that they can execute first. At the same time, you also need to pay attention to the scope of the interceptor chain, in general, you can configure the interceptor chain in the global scope so that multiple actions can be shared, or you can configure a custom interceptor chain in a single action to meet specific needs.

In short, configuring the interceptor chain is a very important part of the Struts2 framework, mastering the configuration methods and precautions of the interceptor chain, can better realize the interception and control of Action requests, and improve the security and reliability of web applications.

Please explain the Ajax introduction in detail

Ajax (Asynchronous JavaScript and XML) is a web development technique that enables asynchronous data interaction with a server without reloading the entire web page, enabling the ability to dynamically update page content.

The core technology of Ajax is to achieve asynchronous communication with the server through the XMLHttpRequest object, which can interact with the server in the background without affecting the user’s current operation. Compared with traditional web pages, the use of Ajax technology can make the page have a higher user experience and faster response speed, and improve the interactivity and practicality of web applications.

Web applications that use Ajax technology typically include the following features:

1. Asynchronous data interaction: Ajax technology can be used to interact with the server with asynchronous data without refreshing the entire page, so as to realize the function of dynamically updating the page content.
2. Implementation using JavaScript: Ajax technology relies heavily on JavaScript and XMLHttpRequest objects to achieve asynchronous communication with the server and page updates through JavaScript.
3. Standardization-based web technologies: Ajax technology is based on standardized web technologies, such as XML, HTML, CSS, JavaScript and HTTP, etc., and have good cross-platform and portability.
4. Improve the interactivity and usability of web applications: The use of Ajax technology can make web applications have a higher user experience and faster response speed, and improve the interactivity and practicality of web applications.

In conclusion, Ajax technology is a very important web development technology that can make web applications have a higher user experience and better interactivity, which is one of the skills that web developers must master.

Please explain in detail the integration of Struts with Ajax

In Struts2, it can be easily integrated with Ajax technology to process and respond to Ajax requests by using the built-in Ajax tag library and associated JavaScript libraries. Here’s an example of a simple Struts2 integration with Ajax:

1. Introduce related JavaScript libraries such as jQuery and json2 .js in the Struts2 project.
2. Use Struts2’s built-in Ajax tag library in JSP pages, such as <s:url>, <s:submit>, <s:form>, <s:div>, etc., to process and respond to Ajax requests. For example:

jspCopy code<s:url var="ajaxUrl" action="ajaxAction"/>
<s:form id="ajaxForm">
   <s:textfield name="username" label="用户名"/>
   <s:password name="password" label="密码"/>
   <s:submit value="登录" onclick="ajaxLogin()"/>
</s:form>
<s:div id="ajaxResult"/>

In the above example, the URL address of the Ajax request was defined using the <s:url> tag, a form containing the username, password, and login button was defined using the <s:form> tag, and the ajaxLogin() function was triggered using the onclick event. Using the <s:div> tag defines an area that displays the results of the Ajax response.

3. Write the ajaxLogin() function in JavaScript code to implement the processing and response to Ajax requests. For example:

javascriptCopy codefunction ajaxLogin() {
   $.ajax({
       type: "POST",
       url: $("#ajaxUrl").val(),
       data: $("#ajaxForm").serialize(),
       success: function(response) {
           $("#ajaxResult").html(response);
       },
       error: function() {
           alert("请求失败，请稍后重试！");
       }
   });
}

In the above example, the processing and response to Ajax requests is implemented using the $.ajax() method in the jQuery library. Use type to specify the type of request, url to specify the URL address of the request, data to specify the parameters of the request, success to specify the handler after the response is successful, and error to specify the handler function after the response fails.

4. Define the Action class and methods for handling Ajax requests in Struts2, for example:

javaCopy codepublic class AjaxAction extends ActionSupport {
   private String username;
   private String password;

   public String execute() {
       // 处理Ajax请求
       return SUCCESS;
   }

   // getter和setter方法
}

In the above example, a class named Action is defined and the execute() method is implemented, where Ajax requests can be processed and the response result returned.AjaxAction

Through the above steps, Struts2 can be integrated with Ajax to process and respond to Ajax requests. In actual development, you can choose the appropriate Ajax technology and JavaScript library according to your specific needs to achieve more complex functions and better user experience.

Please explain in detail how to implement an Ajax example

Below is a simple Ajax example that demonstrates how to implement asynchronous requests and responses to server-side data through Ajax technology.

1. Create a Java web project and introduce related JavaScript libraries such as jQuery and json2.js.
2. Create a JSP page and write the relevant HTML and JavaScript code to handle and respond to Ajax requests. For example:

jspCopy code<html>
   <head>
       <title>Ajax示例</title>
       <script type="text/javascript" src="jquery.min.js"></script>
       <script type="text/javascript" src="json2.js"></script>
   </head>
   <body>
       <h2>Ajax示例</h2>
       <form id="ajaxForm">
           <label for="username">用户名：</label>
           <input type="text" id="username" name="username"/>
           <br/>
           <label for="password">密码：</label>
           <input type="password" id="password" name="password"/>
           <br/>
           <input type="button" value="登录" onclick="ajaxLogin()"/>
       </form>
       <div id="ajaxResult"></div>
       <script type="text/javascript">
           function ajaxLogin() {
               $.ajax({
                   type: "POST",
                   url: "ajaxServlet",
                   data: {
                       username: $("#username").val(),
                       password: $("#password").val()
                   },
                   dataType: "json",
                   success: function(response) {
                       if (response.success) {
                           $("#ajaxResult").html("登录成功！");
                       } else {
                           $("#ajaxResult").html("登录失败，请重试！");
                       }
                   },
                   error: function() {
                       $("#ajaxResult").html("请求失败，请稍后重试！");
                   }
               });
           }
       </script>
   </body>
</html>

In the example above, a form containing a username, password, and login button is defined using the <form> tag, and the input boxes and buttons in the form are defined using the <input> tag. Using <div> tags defines an area that displays the results of the Ajax response.

A JavaScript function called ajaxLogin() is defined using <script> tag, which uses the $.ajax() method from the jQuery library to process and respond to Ajax requests. Use type to specify the type of request, url to specify the URL address of the request, data to specify the parameters of the request, dataType to specify the type of response data, success to specify the handler function after the response succeeds, and error to specify the handler function after the response fails.

3. Create a Java servlet and write the Java code to handle and respond to Ajax requests. For example:

javaCopy codeimport java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONObject;

public class AjaxServlet extends HttpServlet {
   private static final long serialVersionUID = 1L;

   protected void doPost(HttpServletRequest request, HttpServletResponse response) 
           throws ServletException, IOException {
       String username = request.getParameter("username");
       String password = request.getParameter("password");

       JSONObject json = new JSONObject();
       if ("admin".equals(username) && "admin123".equals(password)) {
           json.put("success", true);
       } else {
           json.put("success", false);
       }

       response.setContentType("application/json;charset=utf-8");
       PrintWriter out = response.getWriter();
       out.print(json);
       out.flush();
       out

Please continue

In the example above, a Java Servlet class named AjaxServlet is created and the doPost() method is implemented, in which Ajax requests can be processed and the response result returned.

In this method, use the request.getParameter() method to get the parameter values of the Ajax request, i.e. username and password. Use the net.sf.json.JSONObject class to create a JSON object, and set the corresponding property value, that is, the success property, according to the verification result of the user name and password. Use the response.setContentType() method to set the Content-Type type of the response to application/json; charset=utf-8, using the PrintWriter class, outputs the string form of a JSON object to the response.

Through the above steps, you can implement a simple Ajax example, which demonstrates how to implement asynchronous requests and responses to server-side data through Ajax technology. In actual development, you can choose the appropriate Ajax technology and JavaScript library according to specific needs to achieve more complex functions and better user experience.

Please explain in detail how to implement the practical case: a simple CRUD application, please do the project requirements analysis first

A simple CRUD application is a basic database management application, which can realize basic operations such as adding, deleting, modifying, and checking data in the database. The following is a project requirements analysis of a simple CRUD application based on the Struts2 framework:

1. Requirements overview

The application needs to add, delete, modify, and check the data in the database, and the specific requirements are as follows:

• Users can browse all the data and display it in pages;
• Users can add a piece of data and validate the data when submitting the form;
• Users can edit a piece of data and validate the data when submitting the form;
• The user can delete a piece of data and confirm it twice.

2. Database design

The application needs to access the database, so you need to design the database table structure first. Suppose the application needs to manage a student information table with the following fields:

• ID: Student number, primary key;
• name: student’s name, required, no more than 50 characters in length;
• gender: student gender, required, value range is “male” or “female”;
• age: Student age, required, the value range is an integer between 1~150.

Therefore, you can design a database table named “student” that contains the following fields:

sqlCopy codeCREATE TABLE `student` (
   `id` int(11) NOT NULL AUTO_INCREMENT,
   `name` varchar(50) NOT NULL,
   `gender` varchar(10) NOT NULL,
   `age` int(11) NOT NULL,
   PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

3. Interface design

The application needs to realize operations such as adding, deleting, modifying, and checking student information, so it is necessary to design the corresponding interface.

• Home: This page is used to display all student information, and provides pagination functions and links to other action pages;
• Add page: This page is used to add a new piece of student information, including an input box and submit button such as name, gender, age, etc.;
• Edit page: This page is used to edit an existing student information, including an input box and submit button such as name, gender, age, etc.;
• Delete page: This page deletes an existing piece of student information, including a confirmation button and a cancel button.

4. Functional requirements

Based on the above requirements overview and interface design, specific functional requirements can be listed, as follows:

• Home:
  • Display all student information;
  • Provide pagination function;
  • Provide the ability to link to the added page;
  • Provide the ability to link to the editing page;
  • Provides the ability to link to a deleted page.
• To add a page:
  • Provide an input field for entering the student’s name;
  • Provide a drop-down box to select the student’s gender;
  • Provide an input field for entering the age of the student;
  • Provide form validation function to verify whether the entered data meets the requirements;
  • Provides the ability to submit forms to add new student information to the database.
• To edit a page:
  • Gets the student based on the specified student number

Please continue

Details including name, gender, age, etc.;

• Display the student’s details in the input box;
• Provide form validation function to verify whether the entered data meets the requirements;
• Provides the ability to submit forms to update modified student information to the database.
• To delete a page:
  • According to the assigned student number, obtain the details of the student, including name, gender, age, etc.;
  • Display the student’s details on the page;
  • Provide a secondary confirmation function to confirm whether to delete the student’s information;
  • If the deletion is confirmed, the student information is deleted from the database.

5. Technical implementation

The application is implemented based on the Struts2 framework and requires the following technologies:

• Struts2 framework: used to implement the MVC pattern, handling requests and responses;
• JSP pages: used to present data and process user input;
• Servlet: Used to receive and process requests, and call service-layer methods to implement business logic;
• Service layer: used to implement business logic, including accessing databases, data validation, etc.;
• Database: Used to store and manage student information.

Through the above project requirements analysis, we can clearly understand the functions and implementation methods of the application, and provide guidance and help for subsequent development work.

Please explain in detail the implementation database design and construction

In a CRUD application based on the Struts2 framework, it is necessary to implement operations such as adding, deleting, modifying, and querying student information, so it is necessary to design the database table structure and create the corresponding table in the database.

Here are the steps to design and create a student information table based on a MySQL database:

1. Design the data table structure

The student information form needs to contain the following fields:

• ID: Student number, primary key;
• name: student’s name, required, no more than 50 characters in length;
• gender: student gender, required, value range is “male” or “female”;
• age: Student age, required, the value range is an integer between 1~150.

Therefore, you can design a database table named “student” that contains the following fields:

sqlCopy codeCREATE TABLE `student` (
   `id` int(11) NOT NULL AUTO_INCREMENT,
   `name` varchar(50) NOT NULL,
   `gender` varchar(10) NOT NULL,
   `age` int(11) NOT NULL,
   PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

2. Create a database table

In a MySQL database, you can create a database table named “student” with the following command:

sqlCopy codeCREATE TABLE student (
  id INT(11) NOT NULL AUTO_INCREMENT,
  name VARCHAR(50) NOT NULL,
  gender VARCHAR(10) NOT NULL,
  age INT(11) NOT NULL,
  PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

This command creates a database table named “student”, which contains four fields: id, name, gender, and age, id as the primary key, data type as INT(11), name and gender data type as VARCHAR(50) and VARCHAR(10), and age data type as INT(11).

Through the above steps, a database table named “student” can be created in the MySQL database, which is used to store the basic information of students and provide basic data support for subsequent development work.

Please continue

3. Insert sample data

Before the CRUD operation, you can insert some sample data into the student information table to facilitate subsequent testing and debugging.

You can use the following command to insert three pieces of sample data into the student information table:

sqlCopy codeINSERT INTO student (name, gender, age) VALUES ('Tom', '男', 20);
INSERT INTO student (name, gender, age) VALUES ('Lucy', '女', 22);
INSERT INTO student (name, gender, age) VALUES ('Jack', '男', 21);

The command inserts three pieces of data into the student information table, namely Tom, Lucy and Jack’s basic information, including name, gender, and age.

Through the above steps, you can create a database table named “student” in the MySQL database and insert some sample data into it to provide basic data support for subsequent development work.

Please continue

4. Database connection configuration

Accessing a MySQL database in a Java application requires the use of the JDBC (Java Database Connectivity) driver. You can add dependencies for the MySQL JDBC driver to your project and then configure the database connection information using:

xmlCopy code<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/mydb</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">123456</property>

Among them, com.mysql.jdbc.Driver is the class name of the MySQL JDBC driver, localhost:3306/mydb is the address and database name of the MySQL database, root is the user name of the database, and 123456 is the password of the database.

Through the above steps, the MySQL database can be accessed in the Java application, and the connection information is configured, which provides data access support for subsequent development work.

Please explain in detail the implementation of ActionForm, Action, and JSP pages

In the Struts2 framework, ActionForm, Action, and JSP pages are the three core components that implement the MVC pattern for handling requests and responses. The implementation of each of these three components is described in detail below.

1. Implementation of ActionForm

ActionForm is used to encapsulate user-submitted form data with various properties and methods for validating and processing form data. In the Struts2 framework, ActionForm can be implemented in the following ways:

javaCopy codepublic class StudentForm extends ActionForm {

    private int id;
    private String name;
    private String gender;
    private int age;

    // getter和setter方法
}

In the above code, StudentForm inherits the ActionForm class and defines four properties: id, name, gender, and age, which are used to encapsulate the basic information of the student. In actual development, you can add additional properties and methods as needed to meet your business needs.

2. Implementation of Action

Actions are used to receive and process requests and return the processing results to the user, with methods that execute business logic and some other methods for processing request parameters and forwarding requests. In the Struts2 framework, Actions can be implemented in the following ways:

javaCopy codepublic class StudentAction extends ActionSupport implements ModelDriven<StudentForm> {

    private StudentForm form = new StudentForm();
    private List<Student> students = new ArrayList<Student>();

    @Override
    public StudentForm getModel() {
        return form;
    }

    public String list() {
        // 获取所有学生信息
        students = studentService.getAllStudents();
        return SUCCESS;
    }

    public String add() {
        // 添加学生信息
        studentService.addStudent(form);
        return SUCCESS;
    }

    public String edit() {
        // 编辑学生信息
        studentService.editStudent(form);
        return SUCCESS;
    }

    public String delete() {
        // 删除学生信息
        studentService.deleteStudent(form.getId());
        return SUCCESS;
    }

    // getter和setter方法
}

In the above code, StudentAction inherits the ActionSupport class and implements the ModelDriven interface for encapsulation and processing of form data. This class contains four methods, list, add, edit, and delete, which are used to get all student information, add student information, edit student information, and delete student information. In actual development, you can add additional methods and properties as needed to meet your business needs.

3. Implementation of JSP pages

JSP pages are used to present data and process user input, typically including elements such as forms, links, buttons, etc. In the Struts2 framework, JSP pages can be implemented in the following ways:

htmlCopy code<%@ taglib uri="/struts-tags" prefix="s" %>

<html>
<head>
  <title>学生信息管理系统</title>
</head>
<body>

  <h1>学生信息管理系统</h1>

  <s:form action="list">
    <s:submit value="查询学生信息" />
  </s:form>

  <s:form action="add">
    <s:textfield name="name" label="姓名" />
    <s:radio name="gender" label="性别" list

Please continue

phpCopy code<s:submit value="添加学生信息" />

</s:form>

<s:form action=”edit”> <s:hidden name=”id” /> <s:textfield name=”name” label=”姓名” /> <s:radio name=”gender” label=”性别” list=”#{‘男’:’男’,’女’:’女’}” /> <s:textfield name=”age” label=”年龄” /> <s:submit value=”修改学生信息” /> </s:form>

<s:form action=”delete”> <s:hidden name=”id” /> <s:submit value=”删除学生信息” /> </s:form> <table border=”1″> <tr> <th>编号</th> <th>姓名</th> <th>性别</th> <th>年龄</th> <th>操作</th> </tr> <s: iterator value=”students”> <tr> <td><s:property value=”id” /></td> <td><s:property value=”name” /></td> <td><s:property value=”gender” /></td> <td><s:property value=”age” /></td> <td> <s: url id=”editUrl” action=”edit”> <s:param name=”id”><s:property value=”id” /></s:param> </s:url> <s:url id=”deleteUrl” action=”delete”> <s:param name=”id”><s:property value=”id” /></s:param> </s:url> <s: a href=”%{editUrl}”>编辑</s:a> <s:a href=”%{deleteUrl}”>删除</s:a> </td> </tr> </s:iterator> </table> </body> </html> “`

In the above code, Struts2’s tag library is used to generate forms, links, buttons, and other elements. This page contains four forms, LIST, ADD, EDIT, and delete, which are used to query student information, add student information, edit student information, and delete student information. Basic information for all students is displayed in a table, with edit and delete actions. In actual development, you can add additional elements and attributes as needed to meet your business needs.

Please explain in detail how to implement a Data Access Layer (DAO)

In the Struts2 framework, the data access layer (DAO) is used to implement data persistence and query operations, including database access and data processing functions. Here’s how to implement a simple data access layer.

1. Definition of the DAO interface

First, define a DAO interface that encapsulates the basic operations of data access, such as adding, deleting, modifying, and querying.

javaCopy codepublic interface StudentDao {

    public void addStudent(Student student);

    public void editStudent(Student student);

    public void deleteStudent(int id);

    public Student getStudentById(int id);

    public List<Student> getAllStudents();

}

In the above code, the StudentDao interface defines five basic operations, including adding student information, editing student information, deleting student information, querying student information based on ID, and getting all student information, etc.

2. The DAO implements the writing of classes

Next, implement a StudentDao implementation class that concretely implements the basic operations defined in the DAO interface.

javaCopy codepublic class StudentDaoImpl implements StudentDao {

    private SessionFactory sessionFactory;

    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }

    @Override
    public void addStudent(Student student) {
        Session session = sessionFactory.getCurrentSession();
        session.save(student);
    }

    @Override
    public void editStudent(Student student) {
        Session session = sessionFactory.getCurrentSession();
        session.update(student);
    }

    @Override
    public void deleteStudent(int id) {
        Session session = sessionFactory.getCurrentSession();
        Student student = (Student) session.get(Student.class, id);
        session.delete(student);
    }

    @Override
    public Student getStudentById(int id) {
        Session session = sessionFactory.getCurrentSession();
        Student student = (Student) session.get(Student.class, id);
        return student;
    }

    @Override
    public List<Student> getAllStudents() {
        Session session = sessionFactory.getCurrentSession();
        Query query = session.createQuery("from Student");
        List<Student> students = query.list();
        return students;
    }

}

In the above code, the StudentDaoImpl class implements the StudentDao interface and defines the specific implementation methods of the five basic operations. The class contains the SessionFactory property and the setSessionFactory method for connecting to databases and manipulating data tables. In actual development, you can add additional methods and properties as needed to meet your business needs.

3. Writing DAO configuration files

Finally, you need to configure information about the DAO implementation class in your project to implement the management and invocation of the data access layer.

xmlCopy code<bean id="studentDao" class="com.example.dao.StudentDaoImpl">
  <property name="sessionFactory" ref="sessionFactory" />
</bean>

In the above code, the management and invocation of the DAO implementation class is implemented by configuring a bean named studentDao, where the class attribute specifies the class name of the concrete implementation class, and the property property specifies the property name of the dependency injection and the reference name of the dependent object.

Through the above steps, a simple data access layer can be implemented for adding, deleting, modifying, checking and other operations on student information, and providing DAO interfaces, DAO implementation classes and DAO configuration files

Please explain in detail the implementation of the business logic layer (Service)

In the Struts2 framework, the business logic layer (Service) is used to implement business logic processing, including transaction management, data validation, data transformation and other functions. Here’s how to implement a simple business logic layer.

1. The definition of the service interface

First, define a service interface that encapsulates the basic operations of business logic, such as adding, deleting, modifying, and searching.

javaCopy codepublic interface StudentService {

    public void addStudent(StudentDto studentDto);

    public void editStudent(StudentDto studentDto);

    public void deleteStudent(int id);

    public StudentDto getStudentById(int id);

    public List<StudentDto> getAllStudents();

}

In the above code, the StudentService interface defines five basic operations, including adding student information, editing student information, deleting student information, querying student information based on ID, and getting all student information.

2. The writing of the Service implementation class

Next, implement an implementation class of StudentService that concretely implements the basic operations defined in the Service interface.

javaCopy code@Service("studentService")
@Transactional
public class StudentServiceImpl implements StudentService {

    @Autowired
    private StudentDao studentDao;

    @Override
    public void addStudent(StudentDto studentDto) {
        Student student = new Student();
        BeanUtils.copyProperties(studentDto, student);
        studentDao.addStudent(student);
    }

    @Override
    public void editStudent(StudentDto studentDto) {
        Student student = studentDao.getStudentById(studentDto.getId());
        BeanUtils.copyProperties(studentDto, student);
        studentDao.editStudent(student);
    }

    @Override
    public void deleteStudent(int id) {
        studentDao.deleteStudent(id);
    }

    @Override
    public StudentDto getStudentById(int id) {
        Student student = studentDao.getStudentById(id);
        StudentDto studentDto = new StudentDto();
        BeanUtils.copyProperties(student, studentDto);
        return studentDto;
    }

    @Override
    public List<StudentDto> getAllStudents() {
        List<Student> students = studentDao.getAllStudents();
        List<StudentDto> studentDtos = new ArrayList<>();
        for (Student student : students) {
            StudentDto studentDto = new StudentDto();
            BeanUtils.copyProperties(student, studentDto);
            studentDtos.add(studentDto);
        }
        return studentDtos;
    }

}

In the above code, the StudentServiceImpl class implements the StudentService interface and defines the specific implementation methods of the five basic operations. This class uses Spring’s dependency injection mechanism to inject StudentDao objects into the Service implementation class through @Autowired annotations, thus implementing calls to the DAO layer. In actual development, you can add additional methods and properties as needed to meet your business needs.

3. Writing of service configuration files

Finally, you need to configure information about the Service implementation class in your project to implement management and invocation of the business logic layer.

xmlCopy code<bean id="studentService" class="com.example.service.StudentServiceImpl">
  <property name="studentDao" ref="studentDao" />
</bean>

In the above code, the management and call of the Service implementation class is implemented by configuring a bean named studentService, where the class property specifies the class of the concrete implementation class

Please explain the project structure and naming convention in detail

When developing the Struts project, a good project structure and naming convention can improve the maintainability and extensibility of the project, making the code clearer and easier to understand. Here is a commonly used Struts project structure and naming convention:

1. Project structure

In the Struts project, the MVC (Model-View-Controller) pattern is usually used for development, so the following directory structure is recommended:

lessCopy code- src/main/java                // Java源代码目录
  - com.example.model          // 存放Model类的目录
  - com.example.dao            // 存放DAO类的目录
  - com.example.service        // 存放Service类的目录
  - com.example.action         // 存放Action类的目录
- src/main/resources           // 资源文件目录
  - applicationContext.xml   // Spring配置文件
  - struts.xml                 // Struts配置文件
- WebContent                   // Web应用根目录
  - WEB-INF                    // WEB-INF目录
    - lib                      // 存放第三方库文件的目录
    - classes                  // 存放编译后的Java类文件的目录
    - spring                   // 存放Spring相关配置文件的目录
    - struts                   // 存放Struts相关配置文件的目录
    - web.xml                  // Web应用配置文件
  - index.jsp                  // 首页文件

In the above directory structure, it is recommended to store Java source code, resource files and web applications in different directories to improve the maintainability of the project.

2. Naming convention

In the Struts project, the following naming convention is recommended:

• Java classes should be named using camel nomenclature, such as StudentAction, StudentService, StudentDao, etc.
• The name of the Action class should end with Action, such as StudentAction.
• The name of the DTO class should end with Dto, such as StudentDto.
• The naming of DAO classes should end with Dao, such as StudentDao.
• Service classes should be named with Service, such as StudentService.
• The Model class should be named after the name of the entity class, such as Student.
• The action name in the Struts configuration file should be a combination of lowercase letters and dashes, such as /student/show.
• JSP pages should be named in a combination of lowercase letters and underscores, such as student_list.jsp.

By following the above project structure and naming conventions, you can improve the maintainability and extensibility of the project, make the code clearer and easier to understand, and reduce the possibility of errors.

Please explain the performance tuning recommendations in detail

When developing the Struts project, in order to ensure the performance and stability of the application, the following points need to be noted:

1. Reduce the number of page requests

In web applications, page requests are very resource-intensive, so minimizing the number of page requests can effectively improve the performance of the application. You can reduce the number of page requests in the following ways:

• Use CSS and JavaScript files for page styling and scripting, avoiding the use of style and script tags in HTML;
• Use Sprite technology to merge multiple images into one image to reduce the number of page requests;
• For the display of a large amount of data, use pagination and scroll loading to avoid loading too much data at one time.

2. Avoid using redirects

Redirects are redirects of client requests to another URL address, which can cause additional network overhead and server burden, so redirects should be avoided as much as possible.

3. Fair use of caching

In web applications, caching can effectively reduce server pressure and improve application performance. You can use caching in the following ways:

• For static files (such as CSS, JavaScript, images, etc.), you can cache them in the browser to avoid the need to fetch each request from the server;
• Dynamically generated data can be optimized using a caching mechanism to avoid the need to regenerate the data for each request.

4. Avoid using a large number of Session objects

In web applications, Session objects are used to store user session information, if each user uses a Session object, it will cause excessive consumption of server memory resources, so you should try to avoid using a large number of Session objects.

5. Use database connection pooling wisely

When working with databases, you should use database connection pooling for connection management to reduce the overhead of database connections and improve the performance of your application. You can use database connection pooling in the following ways:

• Set an appropriate connection pool size to avoid failure to meet requests due to too small a connection pool, or waste of resources due to too large.
• Set the timeout period of the connection pool reasonably to avoid waste of resources caused by connections being occupied for a long time.
• Use the idle connection recycling mechanism to reclaim and release connections to avoid wasting resources caused by long-term connections.

Through the above performance optimization suggestions, you can effectively improve the performance and stability of your application.

Please explain the security recommendations in detail

When developing the Struts project, in order to ensure the security of the application, the following points need to be noted:

1. Protect against SQL injection attacks

SQL injection attack refers to an attacker entering malicious SQL statements in the input box to obtain or destroy data in the database, so the following measures need to be taken to prevent it:

• The data entered by the user should be filtered and validated to avoid passing malicious SQL statements to the database.
• For database access operations, you should use PreparedStatement or NamedParameterJdbcTemplate to avoid directly using string concatenation.

2. Protect against cross-site scripting attacks

Cross-site scripting attacks are when attackers inject malicious scripts into websites to obtain users’ information, so the following measures need to be taken to prevent them:

• The data entered by the user should be filtered and validated to avoid passing malicious scripts to the website;
• The data output to the page should be HTML escaped to prevent malicious scripts from being executed in the browser.

3. Protect against cross-site request forgery attacks

Cross-site request forgery attacks are malicious actions by attackers who forge website requests, so you need to take the following measures to prevent them:

• For form submission operations, token validation should be added to avoid the submission of malicious requests;
• For sensitive operations (such as modification or deletion operations), users should be required to confirm twice to avoid malicious operations.

4. Use HTTPS protocol appropriately

The HTTPS protocol can encrypt the transmitted data to avoid data theft during transmission, so the HTTPS protocol should be used for protection when making sensitive data transmission.

5. Set permission control reasonably

In the Struts project, access control should be controlled to ensure that only authorized users can access sensitive resources. Permission control can be done using Struts’ built-in interceptor.

Through the above security recommendations, you can effectively improve the security and stability of your application.