java web相同用戶重複登陸，即用戶唯一登錄，後登陸擠掉先登錄的，設置限制用戶同時登陸人數

1、web.xml

<listener>
<description>SessionListener</description>
<listener-class>com.fhc.port.socket.SessionListener</listener-class>
</listener>

2、SessionListener監聽類

package com.fhc.port.socket;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
* @Description: session監聽器用戶唯一登錄，後登陸擠掉先登錄的
*/

public class SessionListener implements HttpSessionListener,
HttpSessionAttributeListener {

// log4j
private final static Log log = LogFactory.getLog(SessionListener.class);

// 保存當前登錄的所有用戶
public static Map<HttpSession, String> loginUserList = new HashMap<HttpSession, String>();

// 用這個作爲session中的key
public static String SESSION_LOGIN_NAME = "beenLoginUser";

// session創建時調用這個方法
@Override
public void sessionCreated(HttpSessionEvent arg0) {

}

// Session失效或者過期的時候調用的這個方法,
@Override
public void sessionDestroyed(HttpSessionEvent event) {
try {
loginUserList.remove(event.getSession());
} catch (Exception e) {
e.printStackTrace();
}
}

// 執行setAttribute的時候, 當這個屬性本來不存在於Session中時, 調用這個方法.
@Override
public void attributeAdded(HttpSessionBindingEvent se) {
// 如果添加的屬性是用戶名, 則加入map中
if (se.getName().equals(SESSION_LOGIN_NAME)) {
loginUserList.put(se.getSession(), se.getValue().toString());
}
}

// 當執行removeAttribute時調用的方法
@Override
public void attributeRemoved(HttpSessionBindingEvent se) {
// 如果移除的屬性是用戶名, 則從map中移除
if (se.getName().equals(SESSION_LOGIN_NAME)) {
try {
loginUserList.remove(se.getValue().toString());
} catch (Exception e) {
log.debug(e);
}
}
}

// 當執行setAttribute時 ,如果這個屬性已經存在, 覆蓋屬性的時候, 調用這個方法
@Override
public void attributeReplaced(HttpSessionBindingEvent se) {
// 如果改變的屬性是用戶名, 則跟着改變map
if (se.getName().equals(SESSION_LOGIN_NAME)) {
loginUserList.put(se.getSession(), se.getValue().toString());
}
}

}

3、login登陸控制類

//userLoin登陸函數

@RequestMapping("/userLogin")
public void userLogin(User user,
HttpServletRequest request,
HttpServletResponse response,
HttpSession session) throws UnsupportedEncodingException{
String result = "{\"result\":\"error\"}";
User loginUser = userManager.getUser(user.getUserName(),user.getPassword());

if (null != loginUser)
{
Role role = roleManager.getRole(loginUser.getRoleIndex());
if (null != role){
boolean loginUserMax = false;
loginUserMax = isLogonUser(loginUser.getUserName());
if(loginUserMax){
result = "{\"result\":\"error2\"}";
operationManager.addOperation(1, user.getUserName(), userMachineName, userRemoteIP, 0x00, "登陸失敗");
}else{
session.setAttribute("beenLoginUser",loginUser.getUserName());
}
if(!loginUserMax){
result = "{\"result\":\"success\"}";
}
}
}else{

}

PrintWriter out = null;
response.setContentType("application/json");
try {
out = response.getWriter();
out.write(result);
} catch (IOException e) {
e.printStackTrace();
}
finally{
out.close();
}
}

//寫一個判斷用戶是否已經登陸的方法,獲取在線登陸的用戶人數
public boolean isLogonUser(String userName) {
Set<HttpSession> keys = SessionListener.loginUserList.keySet();
System.out.println("已經存在的session個數："+keys.size());
if(keys.size() == 2){//限制登陸人數
return true;
}
for (HttpSession key : keys) {
System.out.println("已經存在的session："+key.getId());
if (SessionListener.loginUserList.get(key).equals(userName)) {
key.invalidate();
}
}
return false;
}

4、前臺js

1)login.js

2)login.jsp

<form class="form-vertical login-form" action="/recws/user/userLogin">
<h3 class="form-title">請登錄</h3>
<div class="alert alert-error hide">
<button class="close" data-dismiss="alert"></button>
<span>請輸入用戶名密碼.</span>
</div>
<div class="control-group">

<label class="control-label visible-ie8 visible-ie9">用戶名</label>
<div class="controls">
<div class="input-icon left">
<i class="icon-user"></i>
<input class="m-wrap placeholder-no-fix" type="text" placeholder="用戶名" name="userName" id="userName" value = ""/>
</div>
</div>
</div>
<div class="control-group">
<label class="control-label visible-ie8 visible-ie9">密碼</label>
<div class="controls">
<div class="input-icon left">
<i class="icon-lock"></i>
<input class="m-wrap placeholder-no-fix" type="password" placeholder="密碼" name="password" id="password" value = ""/>
</div>
</div>
</div>
<div class="form-actions">
<label class="checkbox">
<input type="checkbox" id="remember" name="remember"/> 記住我
</label>
<button type="submit" class="btn green pull-right" οnclick="userLogin1()">
登錄 <i class="m-icon-swapright m-icon-white"></i>
</button>

</div>
</form>