解决Request获取请求数据中文乱码问题

package com.huanle.web;
 
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 欢了
 * @version 1.0
 */
@WebServlet("/req3")
public class RequestDemo3 extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("==========字母情况下===========");
        String username = request.getParameter("username");
        System.out.println(username);
    }
 
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

package com.huanle.web;
 
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
 
/**
 * @author 欢了
 * @version 1.0
 *
 * 演示浏览器的URL编码 和 tomcat的URL解码
 * 以及解决默认tomcat字符集中文乱码
 */
public class UrlDemo {
    public static void main(String[] args) throws UnsupportedEncodingException {
        String username = "张三";
 
        //URL编码
        String encode = URLEncoder.encode(username, "UTF-8");
        System.out.println(encode);//%E5%BC%A0%E4%B8%89
 
 
        //URL解码
        String decode = URLDecoder.decode(encode, "UTF-8");
        System.out.println(decode);//张三
 
        //但是tomcat的默认解码是ISO-8859-1，并且底层是写死的
        String tomcatDecode = URLDecoder.decode(encode, "ISO-8859-1");
        System.out.println(tomcatDecode);
 
        /**
         * 解决get请求的中文乱码
         *      将tomcat的乱码，先用tomcat默认的字符集ISO-8859-1转为字节数组  编码
         *      再将字节数组转为字符串  解码
         * */
        byte[] bytes = tomcatDecode.getBytes("ISO-8859-1");
        //可以先遍历看一下
        for (byte b : bytes) {
            System.out.print(b + " ");
        }//-27 -68 -96 -28 -72 -119 
        //换行
        System.out.println();
        //将这些十进制转为字符串
        String s = new String(bytes, "UTF-8");
        System.out.println(s);//张三
    }
}

package com.huanle.web;
 
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 欢了
 * @version 1.0
 *
 * 中文乱码解决方案
 */
@WebServlet("/req4")
public class RequestDemo4 extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.先解决乱码问题Post，因为Post是通过流getReader()方法 传输数据，改变流的编码格式为utf-8
        request.setCharacterEncoding("utf-8");
 
 
        //2.获取username
        System.out.println("==========获取username=========");
        String username = request.getParameter("username");
        System.out.println("解决后" + username);
 
    }
 
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

package com.huanle.web;
 
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 欢了
 * @version 1.0
 *
 * 中文乱码解决方案
 */
@WebServlet("/req4")
public class RequestDemo5 extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
     
        //1.获取username
        System.out.println("==========获取username=========");
        String username = request.getParameter("username");
        System.out.println("解决前:" + username);
 
 
        //2.解决乱码问题Get Get是通过getQueryString
        //  乱码原因，tomcat进行URL解码的时候用的是ISO-8859-1的字符集，和页面字符集不匹配
        //  解决方案：
        //  2.1   先将乱码的数据转成字节数组
        //  2.2   再将字节数组转成字符串
        byte[] bytes = username.getBytes("ISO-8859-1");
        String s = new String(bytes, "UTF-8");
        System.out.println("解决后:" + s);
 
    }
 
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}