jsp 统计在线人数利用HttpSessionListener、HttpSessionBindingListener

package com.test; import java.sql.ResultSet; import java.sql.SQLException; import javax.servlet.http.HttpSessionBindingEvent; import javax.servlet.http.HttpSessionBindingListener; public class UserBean implements HttpSessionBindingListener { private String strUserName = ""; private String userID = ""; public UserBean() { } // 获取企业名称（源于系统管理员表） // 获取企业名称 // 获取部门名称 public String getUserName() { return strUserName; } public void setUserName(String strUserName) { this.strUserName = strUserName; } public void logout() { strUserName = ""; } // 根据strId来判断，当前用户是否登录。 public boolean hasLogOn() { if (userID == null || userID.compareTo("") == 0) { return false; } return true; } public void valueBound(HttpSessionBindingEvent e) { String temp = new String(userID + "(" + strUserName + ")"); System.out.println("登录触发"); OnlineCounter.addUser(temp); } // 已登录用户离线处理 public void valueUnbound(HttpSessionBindingEvent ent) { String temp = new String(userID + "(" + strUserName + ")"); System.out.println("退出触发"); OnlineCounter.removeUser(temp); } public String getUserID() { return userID; } public void setUserID(String string) { userID = string; } }