【学习笔记】深入理解HTTP Session

深入理解HTTP Session
通过监听Session来统计在线人数

public class OnlineCounter {  
  private static long online = 0;    
  public static long getOnline(){ 
      return online; 
    } 
    public static void raise(){ 
      online++; 
    } 
    public static void reduce(){ 
      online--; 
  } 
}  

import javax.servlet.http.HttpSessionEvent; 
import javax.servlet.http.HttpSessionListener; 
public class OnlineCounterListener implements HttpSessionListener{ 
    public void sessionCreated(HttpSessionEvent hse) { 
        OnlineCounter.raise();  
    } 
  public void sessionDestroyed(HttpSessionEvent hse){  
        OnlineCounter.reduce(); 
    } 
}