使用SessionListener统计在线人数

1.编辑监听类:


import javax.servlet.http.HttpSessionListener;


import javax.servlet.http.HttpSessionEvent;


import org.apache.log4j.Logger;






/** *//**


* Session监听器


*/






public class SessionListener implements HttpSessionListener ...{


private Logger logger=Logger.getLogger(this.getClass());




private long count=0;




public synchronized void sessionCreated(HttpSessionEvent se) ...{


this.count=this.count+1;


se.getSession().getServletContext().setAttribute("count",this.count+"");


}




public synchronized void sessionDestroyed(HttpSessionEvent se) ...{


this.count=this.count-1;


se.getSession().getServletContext().setAttribute("count",this.count+"");


}


}

2.注册监听到web.xml:


<web-app>


...


<listener>


<listener-class>com.link2friend.friend.sessionlistener.SessionListener</listener-class>


</listener>


...


</web-app>

3.网页上使用:

<%=application.getAttribute("count")%>