countlistener.java

JavaWeb高级特性书中源代码

package org.it315.listener;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
public class CountListener implements HttpSessionListener 
{
	private int count = 0; //用于统计在线人数的变量
	public void sessionCreated(HttpSessionEvent hse) 
	{
		count++; //session对象创建时count加1
		ServletContext context = hse.getSession().getServletContext();
		context.setAttribute("count",new Integer(count));
	}
	public void sessionDestroyed(HttpSessionEvent hse) 
	{
		count--; //session对象销毁时count减1
		ServletContext context = hse.getSession().getServletContext();
		context.setAttribute("count",new Integer(count));
	}
}