关于防止一个账号在不同机器上重复登录

需求：同一个账号，比如在a电脑登录，b就不能登录，主管理员可以踢掉任何人下线。

1.SessionListener.java 文件

package com.neusoft.core;import java.util.HashMap;import javax.servlet.http.HttpSession;import javax.servlet.http.HttpSessionEvent;import javax.servlet.http.HttpSessionListener;/**        * 项目名称：diablo    * 类名称：SessionListener    * 创建人：极限李。    * 创建时间：2017年4月21日 下午4:50:12    * @version        */public class SessionListener implements HttpSessionListener{public static HashMap<String,String> userMap = new HashMap<String,String>();       public static HashMap<String,HttpSession> sessionMap = new HashMap<String,HttpSession>();@Overridepublic void sessionCreated(HttpSessionEvent httpSessionEvent) {// TODO Auto-generated method stub}@Overridepublic void sessionDestroyed(HttpSessionEvent httpSessionEvent) {// TODO Auto-generated method stubHttpSession session = httpSessionEvent.getSession();          String sessionId = session.getId();          sessionMap.remove(sessionId);          for(String key : userMap.keySet()){              if(userMap.get(key).equals(sessionId)){                  userMap.remove(key);              }          }  }}

2.web.xml

<listener>      <listener-class>com.neusoft.core.SessionListener</listener-class>  </listener>

3.登录controller

String userName = user.getUserName();String sessionid = SessionListener.userMap.get(userName);  System.out.println("sessionid  "+sessionid);if(sessionid != null&&!sessionid.equals("")){   //注销在线用户,如果session id 相同，不销毁。  System.out.println("sessionid不为空");System.out.println("request.getSession().getId() "+request.getSession().getId());   /*if(!sessionid.equals(request.getSession().getId())){         SessionListener.sessionMap.get(sessionid).invalidate();         SessionListener.userMap.put(userName,request.getSession().getId());         SessionListener.sessionMap.put(request.getSession().getId(),request.getSession());     }*/  String message="此账号已经登录";model.addAttribute("message", message);return "redirect:/login.do";}else{ System.out.println("sessionid为空");   if(SessionListener.sessionMap.containsKey(request.getSession().getId())){    System.out.println("执行删除sessionMap");       SessionListener.sessionMap.remove(request.getSession().getId());         for(String key : SessionListener.userMap.keySet()){             if(SessionListener.userMap.get(key).equals(request.getSession().getId())){            System.out.println("执行删除userMap");               SessionListener.userMap.remove(key);             }         }     }     SessionListener.userMap.put(userName,request.getSession().getId());     SessionListener.sessionMap.put(request.getSession().getId(),request.getSession());   queryList();   return "redirect:/main.do";

4.查询当前所有用户

public List<String> queryList(){         HashMap<String,HttpSession> sessionMap = SessionListener.sessionMap;        System.out.println(sessionMap);       System.out.println(sessionMap.size());       System.out.println(sessionMap.toString());       System.out.println(sessionMap.keySet());              List<String> list = new ArrayList<String>();         System.out.println("SessionListener.userMap.keySet()"+SessionListener.userMap.keySet());       for(String key : SessionListener.userMap.keySet()){        System.out.println("key  "+key);           OnlineVo v = new OnlineVo();             v.setLoginname(key);             System.out.println("v.getLoginname()  "+v.getLoginname());           list.add(v.getLoginname());         }         System.out.println("list"+list);       return  list;     }  

 5.执行踢出用户和用户自己点退出或者关闭游览器

@RequestMapping("/addUser.do")public ModelAndView addUser(){ModelAndView modelAndView=new ModelAndView("user/UserAdd");queryList();List<String> queryList = queryList();modelAndView.addObject("queryList", queryList);return modelAndView;}@RequestMapping(value="/xiaxian", method = RequestMethod.GET)      public String getNewForm(HttpServletRequest request){String user = request.getParameter("user");System.out.println("user  "+user);String sessionid = SessionListener.userMap.get(user);  System.out.println("sessionid  "+sessionid);   //注销在线用户,如果session id 相同，不销毁。  System.out.println("开始去除sessionid");System.out.println("request.getSession().getId() "+request.getSession().getId());HttpSession httpSession = SessionListener.sessionMap.get(sessionid);System.out.println("httpSession  "+httpSession);SessionListener.userMap.remove(user);httpSession.invalidate();// SessionListener.sessionMap.remove(sessionid);       /*        SessionListener.userMap.put(user,request.getSession().getId());         SessionListener.sessionMap.put(request.getSession().getId(),request.getSession());*/  String zhiling = request.getParameter("zhiling"); System.out.println("zhiling "+zhiling);if(zhiling.equals("xiaxian")){return "redirect:addUser.do";}else{return "redirect:/login.do";}}

6.jsp 自己点退出，或者关闭浏览器，或者关机，

<button onclick="tuichu()">退出</button>function tuichu(){    alert('进入退出');    var yonghu = $('#yonghu').text();    var zhiling='tuichu';  var stt="user/xiaxian.do?user=" + yonghu +"&zhiling="+zhiling;  window.location.href=stt;    }     /* window.onbeforeunload = onbeforeunload_handler; */         window.onunload = onunload_handler;         /* function onbeforeunload_handler(){             var warning="确认退出?";            return warning;       } */                  function onunload_handler(){             /* var warning="谢谢光临"; */            /*  alert(warning); */             var yonghu = $('#yonghu').text();    var zhiling='tuichu';  var stt="user/xiaxian.do?user=" + yonghu +"&zhiling="+zhiling;  window.location.href=stt;       }  

7.踢人下线

<table  id="table" class="gridtable" border="1"><tr><th width="5%">用户名</th><th width="5%">操作</th></tr><c:forEach items="${queryList}" var="queryList"><tr>    <td>${queryList}</td>  <td><a style="color:blue;cursor:pointer;" onclick="updateRow(this); " >修改</a></td>  </tr>  </c:forEach></table>function updateRow(r){    var zhiling='xiaxian';    var i=r.parentNode.parentNode.rowIndex;    alert("行号"+i);    var bb= document.getElementById('table').rows[i].cells[0].innerText;    alert(bb);    var stt="xiaxian.do?user=" + bb +"&zhiling="+zhiling;    //alert(stt);    window.location.href=stt;    }