Filter的应用——IP计数
2016-04-19 19:24
148 查看
Listener：ServletContext生命周期监听，在项目开启时将统计IP的Map放到ServletContext中
Filter：统计IP访问次数
显示：
package com.app.listener;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
/**
* Application Lifecycle Listener implementation class AListener
*
*/
public class AListener implements ServletContextListener {
/**
* Default constructor.
*/
public AListener() {
// TODO Auto-generated constructor stub
}
/**
* @see ServletContextListener#contextInitialized(ServletContextEvent)
*/
public void contextInitialized(ServletContextEvent sce) {
Map<String,Integer> map = new LinkedHashMap<String,Integer>();
ServletContext application = sce.getServletContext();
application.setAttribute("map", map);
}
/**
* @see ServletContextListener#contextDestroyed(ServletContextEvent)
*/
public void contextDestroyed(ServletContextEvent arg0) {
// TODO Auto-generated method stub
}
}Filter：统计IP访问次数
package com.app.filter;
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;
/**
* Servlet Filter implementation class AFilter
*/
public class AFilter implements Filter {
private FilterConfig fConfig;
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
//得到application中的map
ServletContext application = fConfig.getServletContext();
Map<String,Integer> map = (Map<String, Integer>) application.getAttribute("map");
//获取客户端IP
String ip = request.getRemoteAddr();
//判断IP是否存在
if(map.containsKey(ip)){
int count =map.get(ip);
map.put(ip, count+1);
}else{//第一次访问
map.put(ip, 1);
}
chain.doFilter(request, response);
}
public void init(FilterConfig fConfig) throws ServletException {
this.fConfig = fConfig;
}
public void destroy() {
}
}显示：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%
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 'MyJsp.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>
This is my JSP page. <br>
<table>
<tr>
<th>IP</th>
<th>Count</th>
</tr>
<c:forEach items="${applicationScope.map }" var="entry">
<tr>
<td>${entry.key }</td>
<td>${entry.value }</td>
</tr>
</c:forEach>
</table>
</body>
</html>
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