//登录页面 login.jsp

pageEncoding="UTF-8"%>

登录

String msg = (String)(request.getAttribute("msg")==null?"":request.getAttribute("msg"));

%>

function show(){

if(''!=''){

alert('');

}

}

用户登录
用户名
密 码

//主页面 main.jsp

pageEncoding="UTF-8"%>

登录成功

response.setHeader("Pragma","No-cache");

response.setHeader("Cache-Control","No-cache");

response.setDateHeader("Expires", -1);

response.setHeader("Cache-Control", "No-store");

String userName = "";

userName = (String)(session.getAttribute("userName")==null?"":session.getAttribute("userName"));

%>

var count;

var userMsg = '';

var i =0;

function checkUserOnline(){

$.ajax({

type:"post",

url:"${pageContext.request.contextPath}/checkUserOnline.do",

dataType : "text",

success:function(data){

userMsg = data;

//alert(JSON.stringify(userMsg))

},

error:function(){

alert("获取用户信息失败！");

clearInterval(count);

reLogin();

}

});

if(userMsg=='null'||userMsg==''|| userMsg == 'undefined'){

return;

}else{

//alert(JSON.stringify(userMsg));

clearInterval(count);

reLogin();

}

}

function reLogin(){

window.location = "login.jsp";

}

function checkLogin(){

alert("检查");

count = setInterval("checkUserOnline()",5000);

}

if(!"".equals(userName)){

out.print("登陆成功！
用户名："+userName+"");

}

%>

//控制类 LoginController

package com.zjn.oneLogin.dengLu;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.HashMap;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.ResponseBody;

@Controller

public class LoginController{

/**

* 用户和Session绑定关系

*/

public static final Map USER_SESSION = new HashMap();

/**

* seeionId和用户的绑定关系

*/

public static final Map SESSIONID_USER = new HashMap();

@RequestMapping("/login")

@ResponseBody

public MaptoLogin(HttpServletRequest request, HttpServletResponse response) throws Exception{

//获取请求命令

request.setCharacterEncoding("utf-8");

String servletPath = request.getServletPath();//获取请求路径

String uri = servletPath.substring(1, servletPath.lastIndexOf(".do"));

try{

//登录

if ("login".equals(uri)){

HttpSession session = request.getSession();

String userName = request.getParameter("userName");

String password = request.getParameter("password");

if (userName != null && !"".equals(userName.trim())){

//登录成功

if (login(userName, password)){

//处理用户登录(保持同一时间同一账号只能在一处登录)

userLoginHandle(request);

//添加用户与HttpSession的绑定

USER_SESSION.put(userName.trim(), session);

//添加sessionId和用户的绑定

SESSIONID_USER.put(session.getId(), userName);

System.out.println("添加sessionId和用户的绑定 ==="+session.getId());

System.out.println("用户[" + userName + "] 已上线...");

session.setAttribute("userName", userName);

session.removeAttribute("userMsg");//从session中移除用户信息

//重定向到首页

response.sendRedirect("main.jsp");

}

//登录失败

else{

System.out.println("用户[" + userName + "] 登录失败...");

request.setAttribute("msg", "登录失败，请重新登录！");

//response.sendRedirect("login.jsp");

request.getRequestDispatcher("login.jsp").forward(request, response);

}

}

else{

System.out.println("用户[" + userName + "] 登录失败...");

request.setAttribute("msg", "登录失败，请重新登录！");

//response.sendRedirect("login.jsp");

request.getRequestDispatcher("login.jsp").forward(request, response);//跳转到用户页面，返回请求响应对象

}

}else if ("reLogin".equals(uri)){

//重新登陆

HttpSession session = request.getSession();

String userName = (String)session.getAttribute("userName");

if (session != null){

//销毁相关session

//USER_SESSION.remove(SESSIONID_USER.remove(session.getId()));

session.invalidate();

}

if (userName != null && !"".equals(userName)){

System.out.println("用户[" + userName + "] 已下线...");

}

//重定向到登录页面

response.sendRedirect("login.jsp");

}

}

catch (Exception e){

System.out.println(e.getClass() + e.getMessage());

PrintWriter out = response.getWriter();

out.print("服务器内部错误！");

}

return null;

}

/**

*

* Description:用户登录时的处理

* @param request

* @see

*/

private void userLoginHandle(HttpServletRequest request){

//当前登录的用户

String userName = request.getParameter("userName");

System.out.println("userName=="+userName);

//当前sessionId

//String sessionId = request.getSession().getId();

//删除当前sessionId绑定的用户，用户--HttpSession

//USER_SESSION.remove(SESSIONID_USER.remove(sessionId));

//删除当前登录用户已绑定的HttpSession

HttpSession session = USER_SESSION.remove(userName);//map中的remove方法返回删除value值

if (session != null){

//删除已登录的sessionId绑定的用户

SESSIONID_USER.remove(session.getId());

session.removeAttribute("userName");

session.setAttribute("userMsg", "您的账号已经在另一处登录，您被迫下线！");

}

}

/**

*

* Description: 模拟DB登录判断

* @param userName 用户

* @param password 密码

* @return

* @see

*/

private boolean login(String userName, String password){

return ("peizhongxian".equals(userName) && "123456".equals(password));

}

/**

* 判断用户是否同时登陆同一个用户

*

* */

@RequestMapping(value="/checkUserOnline")

@ResponseBody

public void checkUserOnline(HttpServletRequest request,HttpServletResponse response) throws IOException{

HttpSession session=request.getSession();

PrintWriter out = response.getWriter();

out.print(session.getAttribute("userMsg"));

}

}

//监听器 MyListener

package com.zjn.oneLogin.dengLu;

import javax.servlet.http.HttpSessionEvent;

import javax.servlet.http.HttpSessionListener;

public class MyListener implements HttpSessionListener {

/**

* 实现HttpSessionListener接口监听 监听session的创建事件

*/

public void sessionCreated(HttpSessionEvent se){

String sessionId = se.getSession().getId();

System.out.println("创建session sessionId= " + sessionId);

}

/**

* 实现HttpSessionListener接口监听 监听session的销毁事件

*/

public void sessionDestroyed(HttpSessionEvent se){

String sessionId = se.getSession().getId();

System.out.println("sessionId========="+sessionId);

//当前session销毁时删除当前session绑定的用户信息

//同时删除当前session绑定用户的HttpSession

LoginController.USER_SESSION.remove(LoginController.SESSIONID_USER.remove(sessionId));

System.out.println("销毁session sessionId= " + sessionId);

}

}

//web.xml 文件

com.zjn.oneLogin.dengLu.MyListener