struts2 实现在线人数和访问源的统计。

关于listener和filter的初步学习。

1 关于在线人数的实现：

建立一个静态变量onlinecounter， 当接收到一个session时，onlinecounter++， 当session销毁时 onlinecounter--。

这个 listener类的代码如下：

package com.dr; 

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener; 

import org.apache.log4j.Logger; 

public class OnlineCounter extends HttpServlet implements HttpSessionListener 
    {
    private static Logger log = Logger.getLogger(OnlineCounter.class);
    private static final long serialVersionUID = 1L;  
    private static int sessionCounter = 1;  
    public OnlineCounter(){  
        log.info("OnlineCounter initialized.");  
    }  
    public void sessionCreated(HttpSessionEvent se) {
        sessionCounter++;  
        log.info("session created:" + sessionCounter);  
    }  
    public void sessionDestroyed(HttpSessionEvent se) { 
        sessionCounter--;  
        log.info("session destroied");  
    }  
    public static int getOnlineSession() {  
        return sessionCounter;  
    } 

} 

 
     
    
   
     com.dr.OnlineCounter 
      
    
    

    
  
    
   
    10
   
   
    
   

初始化一个static 的Map， 当filter接收到一次request时， 获得访问地址，如果存在于map中，则值加1，否则为0。

获得访问来源的方式为String path = req.getRequestURI().toString();

这个map要通过ServletRequest request传给jsp。

filter代码：

package com.dr;
import java.io.IOException;
import java.util.HashMap;
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;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.interceptor.ApplicationAware;
public class CountTimes implements Filter {
    
    // 过滤器传来的初始化值
    private String auther ;
    private Integer time;
    static Map
  
   application=new HashMap();
    
    @Override
    public void destroy() {
        
    }
    ServletContext context;
    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest)request ;
        HttpServletResponse resp = (HttpServletResponse)response ;
       // HttpServletApplication app=(HttpServletApplication)application;
        
        String path = req.getRequestURI().toString();
        time=application.get(path);
        if(time==null){
        	time=0;
        }
        time++;
        application.put(path, time);
        request.setAttribute("application", application);
    
            chain.doFilter(req, resp);
         }
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        //取得初始化值    
        auther = filterConfig.getInitParameter("auther");
        context  = filterConfig.getServletContext();
    }
   
}

  

  
         
   
    MyFilter
   
         
   
    com.dr.CountTimes
   
       
   
    
     
  
  
  
     
  
        
   
    MyFilter
        
              
   
         
   
    /*
    
     
  

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030" import= "com.dr.OnlineCounter"  %>
    <%@taglib prefix="s" uri="/struts-tags" %>
    <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>




  


  


在线： <%=  OnlineCounter.getOnlineSession()   %>人





   
    
      ${ entry.key} ${ entry.value}