兩種方法,如何實現(xiàn) SpringBoot 并發(fā)登錄人數(shù)控制,然后再對比下!...
來源：jianshu.com/p/b6f5ec98d790
- demo 技術(shù)選型
- 兩種實現(xiàn)思路
- 比較時間戳
- 隊列踢出
- 比較兩種方法
- 演示
通常系統(tǒng)都會限制同一個賬號的登錄人數(shù)，多人登錄要么限制后者登錄，要么踢出前者，Spring Security 提供了這樣的功能，本文講解一下在沒有使用Security的時候如何手動實現(xiàn)這個功能
本文借鑒了
https://jinnianshilongnian.iteye.com/blog/2039760
如果你是使用 Shiro + Session 的模式，可以閱讀此文
demo 技術(shù)選型- SpringBoot
- JWT
- Filter
- Redis + Redisson
JWT（token）存儲在Redis中，類似 JSessionId-Session的關(guān)系，用戶登錄后每次請求在Header中攜帶jwt 如果你是使用session的話，也完全可以借鑒本文的思路，只是代碼上需要加些改動
兩種實現(xiàn)思路比較時間戳
維護一個 username: jwtToken 這樣的一個 key-value 在Reids中, Filter邏輯如下
圖片不清可點開放大public?class?CompareKickOutFilter?extends?KickOutFilter?{
????@Autowired
????private?UserService?userService;
????@Override
????public?boolean?isAccessAllowed(HttpServletRequest?request,?HttpServletResponse?response)?{
????????String?token?=?request.getHeader("Authorization");
????????String?username?=?JWTUtil.getUsername(token);
????????String?userKey?=?PREFIX?+?username;
????????RBucket?bucket?=?redissonClient.getBucket(userKey);
????????String?redisToken?=?bucket.get();
????????if?(token.equals(redisToken))?{
????????????return?true;
????????}?else?if?(StringUtils.isBlank(redisToken))?{
????????????bucket.set(token);
????????}?else?{
????????????Long?redisTokenUnixTime?=?JWTUtil.getClaim(redisToken,?"createTime").asLong();
????????????Long?tokenUnixTime?=?JWTUtil.getClaim(token,?"createTime").asLong();
????????????//?token?>?redisToken?則覆蓋
????????????if?(tokenUnixTime.compareTo(redisTokenUnixTime)?>?0)?{
????????????????bucket.set(token);
????????????}?else?{
????????????????//?注銷當前token
????????????????userService.logout(token);
????????????????sendJsonResponse(response,?4001,?"您的賬號已在其他設(shè)備登錄");
????????????????return?false;
????????????}
????????}
????????return?true;
????}
}
隊列踢出
imgpublic?class?QueueKickOutFilter?extends?KickOutFilter?{
????/**
?????*?踢出之前登錄的/之后登錄的用戶?默認踢出之前登錄的用戶
?????*/
????private?boolean?kickoutAfter?=?false;
????/**
?????*?同一個帳號最大會話數(shù)?默認1
?????*/
????private?int?maxSession?=?1;
????public?void?setKickoutAfter(boolean?kickoutAfter)?{
????????this.kickoutAfter?=?kickoutAfter;
????}
????public?void?setMaxSession(int?maxSession)?{
????????this.maxSession?=?maxSession;
????}
????@Override
????public?boolean?isAccessAllowed(HttpServletRequest?request,?HttpServletResponse?response)?throws?Exception?{
????????String?token?=?request.getHeader("Authorization");
????????UserBO?currentSession?=?CurrentUser.get();
????????Assert.notNull(currentSession,?"currentSession?cannot?null");
????????String?username?=?currentSession.getUsername();
????????String?userKey?=?PREFIX?+?"deque_"?+?username;
????????String?lockKey?=?PREFIX_LOCK?+?username;
????????RLock?lock?=?redissonClient.getLock(lockKey);
????????lock.lock(2,?TimeUnit.SECONDS);
????????try?{
????????????RDeque?deque?=?redissonClient.getDeque(userKey);
????????????//?如果隊列里沒有此token，且用戶沒有被踢出；放入隊列
????????????if?(!deque.contains(token)?&&?currentSession.isKickout()?==?false)?{
????????????????deque.push(token);
????????????}
????????????//?如果隊列里的sessionId數(shù)超出最大會話數(shù)，開始踢人
????????????while?(deque.size()?>?maxSession)?{
????????????????String?kickoutSessionId;
????????????????if?(kickoutAfter)?{?//?如果踢出后者
????????????????????kickoutSessionId?=?deque.removeFirst();
????????????????}?else?{?//?否則踢出前者
????????????????????kickoutSessionId?=?deque.removeLast();
????????????????}
????????????????try?{
????????????????????RBucket?bucket?=?redissonClient.getBucket(kickoutSessionId);
????????????????????UserBO?kickoutSession?=?bucket.get();
????????????????????if?(kickoutSession?!=?null)?{
????????????????????????//?設(shè)置會話的kickout屬性表示踢出了
????????????????????????kickoutSession.setKickout(true);
????????????????????????bucket.set(kickoutSession);
????????????????????}
????????????????}?catch?(Exception?e)?{
????????????????}
????????????}
????????????//?如果被踢出了，直接退出，重定向到踢出后的地址
????????????if?(currentSession.isKickout())?{
????????????????//?會話被踢出了
????????????????try?{
????????????????????//?注銷
????????????????????userService.logout(token);
????????????????????sendJsonResponse(response,?4001,?"您的賬號已在其他設(shè)備登錄");
????????????????}?catch?(Exception?e)?{
????????????????}
????????????????return?false;
????????????}
????????}?finally?{
????????????if?(lock.isHeldByCurrentThread())?{
????????????????lock.unlock();
????????????????LOGGER.info(Thread.currentThread().getName()?+?"?unlock");
????????????}?else?{
????????????????LOGGER.info(Thread.currentThread().getName()?+?"?already?automatically?release?lock");
????????????}
????????}
????????return?true;
????}
}
比較兩種方法第一種方法邏輯簡單粗暴, 只維護一個key-value 不需要使用鎖，非要說缺點的話沒有第二種方法靈活。
第二種方法我很喜歡，代碼很優(yōu)雅靈活，但是邏輯相對麻煩一些，而且為了保證線程安全地操作隊列，要使用分布式鎖。目前我們項目中使用的是第一種方法
演示下載地址:
https://gitee.com/yintianwen7/taven-springboot-learning/tree/master/login-control
- 運行項目，訪問localhost:8887 demo中沒有存儲用戶信息，隨意輸入用戶名密碼，用戶名相同則被踢出
- 訪問 localhost:8887/index.html 彈出用戶信息, 代表當前用戶有效
- 另一個瀏覽器登錄相同用戶名，回到第一個瀏覽器刷新頁面，提示被踢出
- application.properties中選擇開啟哪種過濾器模式，默認是比較時間戳踢出，開啟隊列踢出 queue-filter.enabled=true
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