解决中文乱码(不可能解决不了)

一.直接上代码

1.1写一个GET和POST代码分别解决中文乱码问题

注意:我们需要了解一个知识点,Tomcat7和Tomcat8之间的不同点,Tomcat8在Get请求中不会产生中文乱码问题,而在Tomcat7的GET请求中会产生中文乱码, Tomcat7和Tomcat8的Post请求都会产生中文乱码,在Tomcat官方文档中提到了Tomcat7和Tomcat8在编码过程中有不同,tomcat7用得是ISO-8859-1编码方式,而Tomcat用的则是"UTF-8"编码格式

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>登录</title>
</head>
<body>
--------------GET请求--------------<br>
<form action="${pageContext.request.contextPath}/LoginServlet"  method="get">
      用户名:<input type="text" name="username"><br>
     密码:<input type="password" name="password"><br>
     <input type="submit" value="登录">
</form>
--------------POST请求--------------<br>
<form action="${pageContext.request.contextPath}/LoginServlet"  method="post">
      用户名:<input type="text" name="username"><br>
     密码:<input type="password" name="password"><br>
     <input type="submit" value="登录">
</form>
</body>
</html>

1.2Servlet代码

package web_servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) 
            throws ServletException, IOException {
        //response.setHeader("content-type","text/html;charset=utf-8");
        String vString=request.getParameterMap().get("username")[0];
        System.out.println("dopost里面的request"+request);
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        System.out.println(username);
        System.out.println(password);
        if("张三".equals(username)&"123".equals(password)){
            response.getWriter().write("登录成功");
            response.getWriter().write(username+password);
        }
        else{
            response.getWriter().write("登录失败");
        }
    }
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) 
            throws ServletException, IOException {
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        System.out.println(username);
        System.out.println(password);
        if("张三".equals(username)&"123".equals(password)){
            response.getWriter().write("登录成功");
            response.getWriter().write(username+password);
        }
        else{
            response.getWriter().write("登录失败");
        }
    }
}

1.3过滤器的配置

package web_Filter;

import java.io.IOException;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;

public class MyEncodingFilter  implements Filter{
    @Override
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub
        System.out.println("过滤器的初始化");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        // TODO Auto-generated method stub
        //1.设置编码格式为UTF-8
        System.out.println("dofilter里面的request"+request);
        HttpServletResponse response2=(HttpServletResponse)response;
        response2.setHeader("content-type", "text/html;charset=utf-8");
        //request.setCharacterEncoding("UTF-8");
        //2.如果编码格式为UTF-8则放行
        
        myRequest myRequest=new myRequest((HttpServletRequest)request);
        chain.doFilter(myRequest, response);
    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        System.out.println("过滤器的销毁");
    }
}
/**
 * Wrapper包装类,内部有个真实对象的引用
 * @author maskpd
 *
 */
class myRequest extends HttpServletRequestWrapper{
    private HttpServletRequest request;
    public myRequest(HttpServletRequest request) {
        super(request);
        this.request=request;
    }
    @Override
    public String getParameter(String name) {
        // TODO Auto-generated method stub
        return null;
    }
    @Override
    public Map<String, String[]> getParameterMap() {
        // TODO Auto-generated method stub
        return super.getParameterMap();
    }
    
}

1.4配置过滤器

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>2020-1-20webproject</display-name>
  <!-- 编码过滤器 -->
  <filter>
        <filter-name>MyEncodingFilter</filter-name>
        <filter-class>web_Filter.MyEncodingFilter</filter-class>  
  </filter>
  <filter-mapping>
        <filter-name>MyEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

二.OK了