<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">

  <display-name>FilterDemo01</display-name>

  <welcome-file-list>

    <welcome-file>index.jsp</welcome-file>

  </welcome-file-list>

  <filter>

    <filter-name>FilterTest01</filter-name>

    <filter-class>com.Higgin.web.filter.FilterTest01</filter-class>

  </filter>

  <filter-mapping>

    <filter-name>FilterTest01</filter-name>

    <url-pattern>/*</url-pattern> <!-- 过滤所有 -->

  </filter-mapping>

</web-app>

package com.Higgin.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;

/**

 * Servlet implementation class ServletTest01

 */

@WebServlet("/ServletTest01")

public class ServletTest01 extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public ServletTest01() {

        super();

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.getWriter().write("中国 加油！China Come on!");   //将"中国 加油！China Come on!"显示在客户端界面上

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);

    }

}

package com.Higgin.web.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 FilterTest01 implements Filter{

    @Override

    public void doFilter(ServletRequest request, ServletResponse response,

            FilterChain chain) throws IOException, ServletException {

        System.out.println("I'm Filter!!!!");

        //直接放行

        chain.doFilter(request, response);//让目标资源执行，即：放行

    }

    @Override

    public void init(FilterConfig arg0) throws ServletException {

    }

    @Override

    public void destroy() {

    }

}

package com.Higgin.web.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 FilterTest01 implements Filter{

    @Override

    public void doFilter(ServletRequest request, ServletResponse response,

            FilterChain chain) throws IOException, ServletException {

        System.out.println("I'm Filter!!!!");

        //对request和response进行一些预处理
 request.setCharacterEncoding("utf-8");

        response.setCharacterEncoding("utf-8");

        response.setContentType("text/html;character=UTF-8");

        chain.doFilter(request, response);//让目标资源执行，即：放行

    }

    @Override

    public void init(FilterConfig arg0) throws ServletException {

    }

    @Override

    public void destroy() {

    }

}