监听器显示登陆用户列表，并实现踢人功能

package cn.csdn.web.listener; import java.util.HashMap; import java.util.Map; import javax.servlet.ServletContext; import javax.servlet.http.HttpSession; import javax.servlet.http.HttpSessionAttributeListener; import javax.servlet.http.HttpSessionBindingEvent; import cn.csdn.web.domain.User; public class SessionAttributeListener implements HttpSessionAttributeListener { public void attributeAdded(HttpSessionBindingEvent se) { Object obj=se.getValue(); if(obj instanceof User){ HttpSession session=se.getSession(); ServletContext context=session.getServletContext(); Map map=(Map) context.getAttribute("map"); if(map==null){//第一个用户登陆，此时不没有创建map集合 map=new HashMap(); context.setAttribute("map",map); } User user=(User) obj; //合建不用户的用户名作业key，登陆用户的session对象做为value map.put(user.getUsername(), session); } } public void attributeRemoved(HttpSessionBindingEvent se) { } public void attributeReplaced(HttpSessionBindingEvent se) { } }