一：分析
统计工作需要在所有资源执行前进行，所以需要放在filter中
这个拦截器仅仅进行统计工作，不进行拦截，所以请求必须继续传递下去
用Map<String,integer>来保存数据，一个IP一个键值对，故整个网站只需要一个Map即可
使用ServletContextListener，在服务器启动时完成创建工作
将Map保存到servletContext中
Map需要在Filter中对数据进行累加操作
Map需要在页面中使用，打印Map中的数据
二：代码
1）jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP 'show.jsp' starting page</title> </head> <body> <h1 align="center">显示结果</h1> <table align="center" width="60%" border="1"> <tr> <th>IP</th> <th>次数</th> </tr> <c:forEach items="${applicationScope.map }" var="entry"> <tr> <td>${entry.key }</td> <td>${entry.value }</td> </tr> </c:forEach> </table> </body> </html>2）Listener
package listener; /** * Created by YuWenHui on 2017/4/9 0009. */ import javax.servlet.ServletContext; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; import java.util.LinkedHashMap; import java.util.Map; public class IPCountListener implements ServletContextListener{ public IPCountListener() { } public void contextInitialized(ServletContextEvent sce) { // 创建map Map<String,Integer> map = new LinkedHashMap<String ,Integer>(); ServletContext application= sce.getServletContext(); application.setAttribute("map",map); } public void contextDestroyed(ServletContextEvent sce) { } }3）Filter
package filter; import javax.servlet.*; import java.io.IOException; import java.util.Map; /** * Created by YuWenHui on 2017/4/9 0009. */ public class IPCountFilter implements Filter { private FilterConfig config=null; public void destroy() { } public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException { // 获取map，从FilterConfig中可以直接获取到，故先将FilterConfig对象私有化，再进行赋值（在init中） ServletContext application = config.getServletContext(); Map<String,Integer> map = (Map<String, Integer>) application.getAttribute("map" ); // 获取ip地址 String ip = req.getRemoteAddr(); // 判断IP是否存在 if (map.containsKey(ip)){ //判断IP是否在map中 int num = map.get(ip); map.put(ip,num+1); }else { map.put(ip,1); } // 保存map application.setAttribute("map",map); chain.doFilter(req, resp); } public void init(FilterConfig config) throws ServletException { this.config=config; } }4）web.xml
<filter> <filter-name>IPCountFilter</filter-name> <filter-class>filter.IPCountFilter</filter-class> </filter> <filter-mapping> <filter-name>IPCountFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
<!-- 配置监听器--> <listener> <listener-class>listener.IPCountListener</listener-class> </listener>