统计工作需要在所有资源之前都执行，那么就可以放到Filter中了。
我们这个过滤器不打算做拦截操作！因为我们只是用来做统计的。
用什么东西来装载统计的数据。Map<String,Integer>
整个网站只需要一个Map即可！
Map什么时候创建（使用ServletContextListener，在服务器启动时完成创建，并只在到ServletContext中），Map保存到哪里！（Map保存到ServletContext中！！！）
1 分析
因为一个网站可能有多个页面，无论哪个页面被访问，都要统计访问次数，所以使用过滤器最为方便。
因为需要分IP统计，所以可以在过滤器中创建一个Map，使用IP为key，访问次数为value。当有用户访问时，获取请求的IP，如果IP在Map中存在，说明以前访问过，那么在访问次数上加1，即可；IP在Map中不存在，那么设置次数为1。
把这个Map存放到ServletContext中！
2 代码<?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"> <filter> <filter-name>MyFilter</filter-name> <filter-class>com.cug.filter02.MyFilter</filter-class> </filter> <filter-mapping> <filter-name>MyFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <listener> <listener-class>com.cug.filter02.MyListener</listener-class> </listener> </web-app>
package com.cug.filter02;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
public class MyListener implements ServletContextListener{
@Override
public void contextDestroyed(ServletContextEvent arg0) {
}
@Override
public void contextInitialized(ServletContextEvent arg0) {
ServletContext context = arg0.getServletContext();
Map<String, Integer> ipMap = new LinkedHashMap<String, Integer>();
context.setAttribute("ipMap", ipMap);
}
}
package com.cug.filter02;
import java.io.IOException;
import java.util.Map;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class MyFilter implements Filter{
private FilterConfig filterConfig;
@Override
public void destroy() {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
ServletContext context = filterConfig.getServletContext();
Map<String, Integer> ipMap = (Map<String, Integer>) context.getAttribute("ipMap");
String ip = request.getRemoteAddr();
if(ipMap.containsKey(ip)){
Integer count = ipMap.get(ip);
ipMap.put(ip,count+1);
}else{
ipMap.put(ip,1);
}
context.setAttribute("ipMap", ipMap);
chain.doFilter(request, response);
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
}
}
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'show.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<table align="center" width="60%" border="1">
<tr>
<th>ip</th>
<th>count</th>
</tr>
<c:forEach items="${applicationScope.ipMap}" var="entry">
<tr>
<td>${entry.key }</td>
<td>${entry.value }</td>
</tr>
</c:forEach>
</table>
</body>
</html>
Java web----Filter之分ip统计网站的访问次数
原文地址：http://blog.csdn.net/bluzelee2011/article/details/42775883
