package cn.mldn.lxh.listener ;

import java.util.* ;
import javax.servlet.* ;
import javax.servlet.http.* ;

public class OnLineDemo 
	implements ServletContextListener,HttpSessionListener,HttpSessionAttributeListener
{
	// 聲明一個(gè)ServletContext對象
	private ServletContext application = null ;
	public void contextInitialized(ServletContextEvent sce)
	{
		// 容器初始化時(shí)，向application中存放一個(gè)空的容器
		this.application = sce.getServletContext() ;
		this.application.setAttribute("alluser",new ArrayList()) ;
	}

	public void contextDestroyed(ServletContextEvent sce)
	{}

	public void sessionCreated(HttpSessionEvent se)
	{}
	public void sessionDestroyed(HttpSessionEvent se)
	{
		// 將用戶名稱從列表中刪除
		List l = (List)this.application.getAttribute("alluser") ;
		String value = (String)se.getSession().getAttribute("uname") ;
		l.remove(value) ;
		this.application.setAttribute("alluser",l) ;
	}

	public void attributeAdded(HttpSessionBindingEvent se)
	{
		// 如果登陸成功，則將用戶名保存在列表之中
		List l = (List)this.application.getAttribute("alluser") ;
		l.add(se.getValue()) ;
		this.application.setAttribute("alluser",l) ;
	}
	public void attributeRemoved(HttpSessionBindingEvent se)
	{}
	public void attributeReplaced(HttpSessionBindingEvent se)
	{}
};
/*
  <listener>
	<listener-class>cn.mldn.lxh.listener.OnLineDemo</listener-class>
  </listener>
*/