Detailed analysis of the implementation principle of Struts2 framework-javaTutorial-php.cn

Detailed analysis of the implementation principle of Struts2 framework

王林

Release： 2024-02-21 17:54:03

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Detailed analysis of the implementation principle of Struts2 framework

Detailed analysis of the implementation principle of the Struts2 framework

As a widely used Java Web application framework, the Struts2 framework’s excellent design and performance make it a favorite among developers. Tools used. Understanding the implementation principles of the Struts2 framework is of great significance to improving developers' understanding and application level of the framework. This article will analyze the implementation principles of the Struts2 framework in detail and provide specific code examples to help readers gain a deeper understanding of this framework.

1. Introduction to Struts2 Framework
The Struts2 framework is a Web application framework based on the MVC design pattern. It provides a rich set of components and functions to facilitate developers to quickly develop Web applications. The Struts2 framework is mainly composed of controller (Action), model (Model) and view (View), and realizes the request and response processing flow through a unified request processing mechanism. In the Struts2 framework, a request is received and processed by the controller, and finally returned to the view for display.

2. Struts2 framework implementation principle

Core components
The core components of the Struts2 framework include filters, interceptors, Actions, configuration files, etc. Among them, the filter is the entrance to the Struts2 framework, used to intercept all requests and process them; the interceptor is used to pre-process and post-process requests; Action is the core component for processing requests, responsible for receiving requests, processing logic and returning As a result; configuration files are used to configure various parameters and components of the framework.
Request processing process
When a request reaches the Struts2 framework, it is first intercepted by the filter, and then the corresponding Action is found and executed based on the information in the configuration file. Before executing the Action, it will be processed through a series of interceptors, which can achieve pre-processing and post-processing of the request. After the Action is executed, a result will be returned to the view and displayed.
Core classes
The core classes of the Struts2 framework include ActionSupport, ActionContext, ActionInvocation, etc. ActionSupport is the implementation class of Action provided by Struts2, which provides some convenient methods and properties; ActionContext is a context object related to the current request, through which request-related information and data can be obtained; ActionInvocation is a part of the request processing chain. Ring, responsible for managing the execution process of requests.

3. Code Example
The following is a simple Struts2 example that demonstrates a simple login function:

Create an Action class named LoginAction, The code is as follows:

package com.example.action;

import com.opensymphony.xwork2.ActionSupport;

public class LoginAction extends ActionSupport {
    private String username;
    private String password;

    @Override
    public String execute() {
        if (username.equals("admin") && password.equals("123456")) {
            return SUCCESS;
        } else {
            return ERROR;
        }
    }

    // Getters and setters
}

Copy after login

Create a view page named login.jsp, the code is as follows:

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
    <title>Login Page</title>
</head>
<body>
    <h1>Login Page</h1>
    <form action="login.action" method="post">
        Username: <input type="text" name="username"><br>
        Password: <input type="password" name="password"><br>
        <input type="submit" value="Login">
    </form>
</body>
</html>

Copy after login

Configure the struts.xml file, specify The mapping relationship between Action and view, the code is as follows:

<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN"
        "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
    <package name="default" extends="struts-default">
        <action name="login" class="com.example.action.LoginAction">
            <result name="success">welcome.jsp</result>
            <result name="error">error.jsp</result>
        </action>
    </package>
</struts>

Copy after login

Through the above code example, we can see how the Struts2 framework handles a simple login function. First, the user fills in the username and password on the login page, and then submits the form. The request is intercepted by the filter of the Struts2 framework and forwarded to LoginAction for processing. Based on the username and password entered by the user, the Action executes the corresponding logic and returns different views based on the results.

To sum up, this article analyzes the implementation principle of the Struts2 framework in detail and provides specific code examples, hoping to help readers better understand and apply this excellent Java Web framework. Through in-depth research and practice, developers can become more proficient in using the Struts2 framework for Web application development, improving development efficiency and code quality.

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