HttpServletRequest应用之实现请求转发

声明

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参考文章链接

(1条消息) B站---【狂神说Java】JavaWeb入门到实战---笔记_夜里的雨的博客-CSDN博客_狂神说java笔记

实现请求转发

1、代码

1.用于实现后台获取登录信息及实现请求转发的LoginServlet代码

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Arrays;

public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        String[] hobbies = req.getParameterValues("hobbies");
        System.out.println("============");
        //后台接收中文乱码问题
        System.out.println(username);
        System.out.println(password);
        System.out.println(Arrays.toString(hobbies));
        System.out.println("============");
        System.out.println(req.getContextPath());
        //通过请求转发
        //这里的 / 代表当前项目的webapp
        req.getRequestDispatcher("/success.jsp").forward(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

其中需要注意这行代码 req.getRequestDispatcher("/success.jsp").forward(req,resp);

这里的 / 代表当前项目的webapp

2.用于注册映射路径的web.xml代码

<?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"
         metadata-complete="true">

    <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>com.xy.servlet.LoginServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/login</url-pattern>
    </servlet-mapping>

</web-app>

3.用于构造用户登录页面的index.jsp代码

<%@page contentType="text/html;" pageEncoding="UTF-8"%>
<html>
<head>
    <title>登录</title>
</head>
<body>

<h1>登录页面</h1>

<div>
    <form action="${pageContext.request.contextPath}/login" method="post">
        用户名 : <input type="text" name="username"> <br>
        密码 : <input type="password" name="password"> <br>
        爱好 :
        <input type="checkbox" name="hobbies" value="打游戏">打游戏
        <input type="checkbox" name="hobbies" value="敲代码">敲代码
        <input type="checkbox" name="hobbies" value="唱歌">唱歌
        <input type="checkbox" name="hobbies" value="看电影">看电影

        <br><br>
        <input type="submit">
    </form>
</div>

</body>
</html>

其中需要注意的是这行代码 action="${pageContext.request.contextPath}/login

${pageContext.request.contextPath} 代表当前项目的网址 http://localhost:8080/request

4.请求转发指向页面的success.jsp代码

<%@ page contentType="text/html; charset=UTF-8" language="java" %>
<html>
    <head>
       <title>Title</title>
       </head>
    <body>
       <h1>登陆成功</h1>
    </body>
</html>