<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <!-- 字符过滤器-->
   <filter>
    <filter-name>EncodingFilter</filter-name>
    <filter-class>com.pro.filter.EncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>EncodingFilter</filter-name>
    <url-pattern>*.jsp</url-pattern>
  </filter-mapping>
  <filter-mapping>
    <filter-name>EncodingFilter</filter-name>
    <url-pattern>*.act</url-pattern>
  </filter-mapping>
  <filter-mapping>
    <filter-name>EncodingFilter</filter-name>
    <url-pattern>*.html</url-pattern>
  </filter-mapping>
    
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

package com.pro.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class EncodingFilter implements Filter {
    private FilterConfig filterConfig = null;
    public void init(FilterConfig fc) throws ServletException {
        this.filterConfig = fc;
    }
    public void doFilter(ServletRequest req, ServletResponse res,
            FilterChain chain) throws IOException, ServletException {
    
        String encoding = filterConfig.getInitParameter("encoding");
        req.setCharacterEncoding(encoding);
        res.setCharacterEncoding(encoding);
        res.setContentType("text/html;charset=" + encoding);
        System.err.println("encoding"+encoding);
        System.err.println(req.getCharacterEncoding());
        System.err.println(res.getCharacterEncoding());
        System.err.println(res.getContentType());
        chain.doFilter(req, res);
    }
    public void destroy() {
        this.filterConfig = null;
    }
}

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

   <form action="test.jsp" method="get">
       <input type="text" name="message" />
       <input type="submit">
   </form>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
   <%=request.getParameter("message") %>