<%@ 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>Insert title here</title>

 </head>

 <body>

 <form action="disp.jsp"> <!-- 相当于使用get -->

     <input type="text" name="info">

     <input type="submit" value="submit">

 </form>

 </body>

 </html>

 <%@ page language="java" contentType="text/html; charset=UTF-8"

     pageEncoding="UTF-8"%>

 <%@ taglib prefix="c" uri="http://www.mldn.cn/jst/core" %>

 <!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>Insert title here</title>

 </head>

 <body>

 <%=request.getParameter("info") %>

 </body>

 </html>

 package org.lxh.filterdemo;

 import java.io.IOException;

 import java.nio.charset.Charset;

 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.HttpServletResponse;

 public class CharacterEncodingFilter implements Filter {

     protected String encoding = null;

     protected FilterConfig filterConfig = null;

     protected boolean enable = false;

     public void destroy() {

         this.encoding = null;

         this.filterConfig = null;

     }

     public void doFilter(ServletRequest request, ServletResponse response,

                            FilterChain chain) throws IOException, ServletException {

         if (this.enable) {

             String encoding = this.selectEncoding(request);

             if (encoding != null && !encoding.equals("")) {

                 System.out.println("~~" + this + ": request :" + encoding);

                 request.setCharacterEncoding(encoding); //Overrides the name of the character encoding used in the body of this request. This method must be called prior to reading request parameters or reading input using getReader().

                 // response.setCharacterEncoding(encoding); // 暂时不太清楚

             }

         }

         // Pass control on to the next filter

         chain.doFilter(request, response);

         if (this.enable) {

             String encoding = this.selectEncoding(request);

             if (encoding != null && !encoding.equals("")) {

                 System.out.println("~~" + this + ": response :" + encoding);

                 response.setCharacterEncoding(encoding);

             }

         }

      }

      public void init(FilterConfig filterConfig) throws ServletException {

          this.filterConfig = filterConfig;

          this.encoding = filterConfig.getInitParameter("encoding");

          if (!Charset.isSupported(encoding)) {

             encoding = null;

          }

          String enableString = filterConfig.getInitParameter("enable");

          if (enableString.equalsIgnoreCase("true")) {

             this.enable = true;

          } else {

             this.enable = false;

          }

       }

       protected String selectEncoding(ServletRequest request) {

           return (this.encoding);

       }

 }