What is the principle of Struts2 framework

The principle of the Struts2 framework: 1. The interceptor parses the request path; 2. Finds the complete class name of the Action; 3. Creates the Action object; 4. Execute the Action method; 5. Returns the result; 6. View parsing. Its principle is based on the interceptor mechanism, which completely separates the business logic controller from the Servlet API, improving the reusability and maintainability of the code. By using the reflection mechanism, the Struts2 framework can flexibly create and manage Action objects to process requests and responses.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

Struts2 is a Web layer framework based on the MVC pattern, which uses an interceptor mechanism to handle user requests. The following is the principle of the Struts2 framework:

1. The interceptor parses the request path: When the user sends a request to the Web application, the interceptor of the Struts2 framework will parse the request path and obtain The name of the Action.

2. Find the complete class name of Action: According to the name of Action, the Struts2 framework will find the corresponding complete class name in the configuration file. These configuration information are usually defined in the struts.xml file.

3. Create an Action object: Once the Struts2 framework finds the complete class name of Action, it will use the reflection mechanism to create an instance of the class (i.e. Action object). This way, a new Action object is created for each request.

4. Execute the Action method: When the Action object is created, the interceptor will hand over the processing of the request to ActionProxy. ActionProxy is the proxy object of the Action object. It executes the corresponding business logic by calling the execute() method of the Action object.

5. Return result: After the Action is executed, a string result (result code) is returned. This result string is usually associated with a view (View), which is used to display the results to the user.

6. View analysis: The Struts2 framework will parse the corresponding view according to the returned result string and display the result to the user. Views can be JSP pages, FreeMarker templates, etc.

The principle of the Struts2 framework is based on the interceptor mechanism, which completely separates the business logic controller from the Servlet API, improving the reusability and maintainability of the code. At the same time, by using the reflection mechanism, the Struts2 framework can flexibly create and manage Action objects to implement request and response processing.

As a classic MVC framework, the Struts2 framework has many advantages and disadvantages. The following is a detailed introduction to the advantages and disadvantages of the Struts2 framework:

Advantages of the Struts2 framework:

1. Rich tag library: provided by Struts2 There are a large number of tag libraries, which can greatly improve development efficiency and simplify the code of the view layer.

2. Interceptor mechanism: Struts2 uses the interceptor mechanism to implement the pre-processing and post-processing functions of requests. This mechanism completely separates the business logic controller from the Servlet API and improves the code's readability. Reusability and maintainability.

3. Type conversion and input verification: Struts2 provides built-in type conversion and input verification functions, which can easily verify and process user input.

4. Internationalization support: Struts2 supports internationalization and can be switched according to different language environments, improving the localization capabilities of applications.

5. Plug-in support: Struts2 provides rich plug-in support, which can easily extend the functions of the framework.

6. Easy to configure and deploy: The Struts2 framework has a clear structure, simple configuration, and can be easily deployed and maintained.

The shortcomings of the Struts2 framework:

1. Interceptor dependency order: The interceptor dependency order of Struts2 is fixed, which may lead to certain In some cases the execution order of interceptors is incorrect.

2. Performance issues: Since Struts2 uses a large number of reflection mechanisms, it may cause performance issues, especially when processing a large number of requests.

3. Steep learning curve: The Struts2 framework is powerful, but the learning curve is relatively steep, and it may take some time for beginners to become familiar with it.

4. Community activity: Although Struts2 is a classic MVC framework, with the emergence of other emerging frameworks, the community activity of Struts2 has declined.

To sum up, the Struts2 framework has rich functions and powerful scalability, but it also has some shortcomings. In actual development, the appropriate framework needs to be selected based on project requirements and team technology stack.

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