解决全站字符乱码（POST和GET中文编码问题）

Posted 2020-10-09 gdwkong

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1　说明

乱码问题：

获取请求参数中的乱码问题；
- POST请求：request.setCharacterEncoding(“utf-8”)；
- GET请求：new String(request.getParameter(“xxx”).getBytes(“iso-8859-1”), “utf-8”)；
  - Tomcat 8.5.20、Tomcat 9.0.0.M26 默认编码都是utf-8,所有不出现GET请求乱码问题，所以不需处理
响应的乱码问题：response.setContextType(“text/html;charset=utf-8”)。

2、当GET请求出现乱码问题时（默认编码为ISO-8859-1时），可采用以下方法解决：

 1 package web.filter;
 2 
 3 import javax.servlet.*;
 4 import javax.servlet.annotation.WebFilter;
 5 import javax.servlet.http.HttpServletRequest;
 6 import java.io.IOException;
 7 
 8 @WebFilter(filterName = "EncodingFilter",urlPatterns = "/*")
 9 public class EncodingFilter implements Filter {
10     public void destroy() { }
11     public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
12         //处理post请求编码问题
13         req.setCharacterEncoding("utf-8");
14 
15         HttpServletRequest request = (HttpServletRequest) req;
16         //处理get请求的编码问题
17         if ( request.getMethod().equals("GET")){
18             EncodingRequest er = new EncodingRequest(request);
19             chain.doFilter(er, resp);
20         } else {
21             chain.doFilter(req,resp);
22         }
23     }
24     public void init(FilterConfig config) throws ServletException { }
25 }

 1 package web.filter;
 2 
 3 import javax.servlet.http.*;
 4 import java.io.UnsupportedEncodingException;
 5 
 6 /**
 7  * 装饰request
 8  */
 9 public class EncodingRequest extends HttpServletRequestWrapper{
10     private HttpServletRequest request ;
11     public EncodingRequest(HttpServletRequest req) {
12         super(req);
13         this.request = req;
14     }
15     public String getParameter(String s) {
16         String value = request.getParameter("s");
17         //处理编码问题
18         try {
19             value = new String(value.getBytes("iso-8859-1"),"utf-8");
20         } catch (UnsupportedEncodingException e) {
21             throw new RuntimeException(e);
22         }
23         return value;
24     }
25 }

 1 package web.servlet;
 2 
 3 import javax.servlet.ServletException;
 4 import javax.servlet.annotation.WebServlet;
 5 import javax.servlet.http.HttpServlet;
 6 import javax.servlet.http.HttpServletRequest;
 7 import javax.servlet.http.HttpServletResponse;
 8 import java.io.IOException;
 9 
10 @WebServlet(name = "AServlet",urlPatterns = "/AServlet")
11 public class AServlet extends HttpServlet {
12     protected void doPost(HttpServletRequest request, HttpServletResponse response)
13             throws ServletException, IOException {
14         response.setContentType("text/html;charset=utf-8");
15         String username = request.getParameter("username");
16         response.getWriter().println(username);
17     }
18 
19     protected void doGet(HttpServletRequest request, HttpServletResponse response)
20             throws ServletException, IOException {
21         response.setContentType("text/html;charset=utf-8");
22         String username = request.getParameter("username");
23         response.getWriter().println(username);
24     }
25 }

 1 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
 2 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
 3 <html>
 4   <head>
 5     <title>$Title$</title>
 6   </head>
 7   <body>
 8   <a href="<c:url value=‘/AServlet?username=张三‘/>">点击这里</a>
 9   <form action="<c:url value=‘/AServlet‘/> " method="post">
10     用户名：<input type="text" name="username" value="李四"/>
11     <input type="submit" value="提交"/>
12   </form>
13   </body>
14 </html>

3、当只有POST请求出现乱码问题时（服务器默认编码为UTF-8时），可采用以下方法解决：

 1 @WebFilter(filterName = "EncodingFilter",urlPatterns = "/*")
 2 public class EncodingFilter implements Filter {
 3     public void destroy() { }
 4     public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
 5         //处理post请求编码问题
 6         req.setCharacterEncoding("utf-8");
 7         chain.doFilter(req,resp);
 8     }
 9     public void init(FilterConfig config) throws ServletException {}
10 }

 1 @WebServlet(name = "AServlet",urlPatterns = "/AServlet")
 2 public class AServlet extends HttpServlet {
 3     protected void doPost(HttpServletRequest request, HttpServletResponse response)
 4             throws ServletException, IOException {
 5         response.setContentType("text/html;charset=utf-8");
 6         String username = request.getParameter("username");
 7         response.getWriter().println(username);
 8     }
 9 
10     protected void doGet(HttpServletRequest request, HttpServletResponse response)
11             throws ServletException, IOException {
12         response.setContentType("text/html;charset=utf-8");
13         String username = request.getParameter("username");
14         response.getWriter().println(username);
15     }
16 }

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