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监听器实现在线人数的统计

2018-01-12 20:31 411 查看

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1. 项目结构

2. 代码

package com;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

/**
* Application Lifecycle Listener implementation class MyContexxtLis
*
*/
@WebListener
public class CountListen implements ServletContextListener {

/**
* Default constructor.
*/
public CountListen() {
// TODO Auto-generated constructor stub
}

/**
* @see ServletContextListener#contextInitialized(ServletContextEvent)
*/
public void contextInitialized(ServletContextEvent arg0) {
arg0.getServletContext().setAttribute("count",100);
}

/**
* @see ServletContextListener#contextDestroyed(ServletContextEvent)
*/
public void contextDestroyed(ServletContextEvent arg0) {
// TODO Auto-generated method stub
}

}

package com;

import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

@WebListener
public class SessionListen implements HttpSessionListener, HttpSessionAttributeListener {

public SessionListen() {
// TODO Auto-generated constructor stub
}

public void attributeRemoved(HttpSessionBindingEvent arg0)  {
System.out.println("remove"+"\t"+arg0.getName()+arg0.getValue());
}

public void attributeAdded(HttpSessionBindingEvent arg0)  {
System.out.println("add"+"\t"+arg0.getName()+arg0.getValue());
}

public void attributeReplaced(HttpSessionBindingEvent arg0)  {
System.out.println("replace"+"\t"+arg0.getName()+arg0.getValue());
}

public void sessionCreated(HttpSessionEvent arg0)  {
System.out.println("session create");
Integer i=(Integer)arg0.getSession().getServletContext().getAttribute("count");
i++;
arg0.getSession().getServletContext().setAttribute("count", i);

}

public void sessionDestroyed(HttpSessionEvent arg0)  {
Integer i=(Integer)arg0.getSession().getServletContext().getAttribute("count");
i--;
arg0.getSession().getServletContext().setAttribute("count", i);
System.out.println("session destroy"+i);

}

}

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%session.setMaxInactiveInterval(3); %>
当前在线人数:${count}
</body>
</html>

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标签： java

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