Request和Response学习笔记4

Request 获取请求参数，中文乱码问题

实例引入：

创建一个html文件：garbled.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>中文乱码问题</title>
</head>
<body>
    <form action="/RequestResponseCharset_war_exploded/demo01" method="get">
        <label><input type="text" name="username" placeholder="请输入用户名"></label><br>
        <label><input type="password" name="password" placeholder="请输入密码"></label><br>
        <input type="submit" value="get提交">
    </form>
    <br>
    <form action="/RequestResponseCharset_war_exploded/demo01" method="post">
        <label><input type="text" name="username" placeholder="请输入用户名"></label><br>
        <label><input type="password" name="password" placeholder="请输入密码"></label><br>
        <input type="submit" value="post提交">
    </form>
</body>
</html>

创建一个类：CharsetGarbled.java

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @Author: YiHua Lee
 * @Version: 1.8.0_201       Java SE 8
 * @Application: IntelliJ IDEA
 * @CreateTime: 2020/5/18 22:10
 * @Description:
 */
@WebServlet("/demo01")
public class CharsetGarbled extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // 获取请求参数
        String username = req.getParameter("username");
        System.out.println(username);
    }

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

启动服务器，浏览器访问：http://localhost:8080/RequestResponseCharset_war_exploded/garbled.html
- get提交
  
  控制台输出：
```
彩虹
```
  浏览器页面跳转到：http://localhost:8080/RequestResponseCharset_war_exploded/demo01?username=%E5%BD%A9%E8%99%B9&password=2018
- post提交
  
  控制台输出：
```
å½©è¹
```
  浏览器页面跳转到：http://localhost:8080/RequestResponseCharset_war_exploded/demo01

解决中文乱码问题

只需要改动doGet()方法即可：

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {
    // 设置流的编码
    req.setCharacterEncoding("utf-8");

    // 获取请求参数
    String username = req.getParameter("username");
    System.out.println(username);
}

重启服务器，再次访问：http://localhost:8080/RequestResponseCharset_war_exploded/garbled.html

并用post提交，控制台输出：
```
彩虹
```
浏览器页面跳转到：http://localhost:8080/RequestResponseCharset_war_exploded/demo01

参考文献

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