Javaweb监听器

package jiantingqi;import javax.servlet.http.HttpSessionEvent;import javax.servlet.http.HttpSessionListener;public class SessionListener implements HttpSessionListener {private static int online=0;public void sessionCreated(HttpSessionEvent arg0) {System.out.println("新增用户");//用户登录在线人数加1++online;System.out.println("online="+online);}public void sessionDestroyed(HttpSessionEvent arg0) {System.out.println("用户退出");//用户退出在线人数减1online--;System.out.println("online="+online);}}