JavaWeb_MVC模式的简单demo

约定不等于承诺〃 2022-05-31 05:35 150阅读 0赞

# JavaWeb\_MVC模式的简单demo #

本文通过实现简单的登录功能来介绍MVC模式

### 1. 项目的目录 ###

![项目目录][eSPf9h0.png]

### 2. login.jsp (包含一个表单，提交用户名、密码等信息) ###

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html>
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Login page</title>
    </head>
    <body>
        <form action="../login.do" method="post">
            <label>用户名 　</label><input type="text" name="userName" /><br /> <br />
            <label>密码　 　</label><input type="password" name="password" /><br /> <br />
            <input type="submit" value="登录" />
        </form>
    </body>
    </html>

### 3. UserBean.java (JavaBean文件,对应登录页面的表单信息) ###

package com.mxh.mvcdemo.demo1;
    
    public class UserBean {
        private String userName;
        private String password;
    
        public String getUserName() {
            return userName;
        }
    
        public void setUserName(String userName) {
            this.userName = userName;
        }
    
        public String getPassword() {
            return password;
        }
    
        public void setPassword(String password) {
            this.password = password;
        }
    }

### 4. Login.java (servlet类，接收login.jsp页面的请求，将表单信息封装到UserBean中，再将请求转发给hone.jsp页面，home.jsp页面作为响应页面返回客户端) ###

package com.mxh.mvcdemo.demo1;
    
    import java.io.IOException;
    
    import javax.servlet.RequestDispatcher;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    @SuppressWarnings("serial")
    public class Login extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            req.setCharacterEncoding("UTF-8");
            resp.setCharacterEncoding("UTF-8");
    
            UserBean user = new UserBean();
            user.setUserName(req.getParameter("userName"));
            user.setPassword(req.getParameter("password"));
    
            req.setAttribute("user", user);
    
            RequestDispatcher view = req.getRequestDispatcher("/demo1/home.jsp");
            view.forward(req, resp);
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            doGet(req, resp);
        }
    }

### 5. web.xml (配置servlet类) ###

<servlet>
        <servlet-name>Login</servlet-name>
        <servlet-class>com.mxh.mvcdemo.demo1.Login</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Login</servlet-name>
        <url-pattern>/login.do</url-pattern>
    </servlet-mapping>

### 6. home.jsp (使用jstl标签输出用户表单提交的内容) ###

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <!DOCTYPE html>
    <html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>Home Page</title>
    </head>
    <body>
        <jsp:useBean id="user" class="com.mxh.mvcdemo.demo1.UserBean" scope="request"></jsp:useBean>
        用户名：<jsp:getProperty property="userName" name="user"    /><br/>
        密码　：<jsp:getProperty property="password" name="user"    />
    </body>
    </html>

### 7. 程序运行效果图 ###

![程序运行效果图1][1]

![程序运行效果图2][2]

### 8. 总结 ###

> jsp为视图层，servlet为控制器，javabean为模型。视图层的数据提交到控制器，控制器将数据封装到模型中，再由视图层操作模型输出数据。

[eSPf9h0.png]: https://i.imgur.com/eSPf9h0.png
[1]: https://i.imgur.com/jEzRPpT.png
[2]: https://i.imgur.com/lrBlJLz.png