通常系统都会限制同一个账号的登录人数,多人登录要么限制后者登录,要么踢出前者,Spring Security 提供了这样的功能,本文讲解一下在没有使用Security的时候如何手动实现这个功能
Demo 技术选型
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SpringBoot
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JWT
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Filter
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Redis + Redisson
JWT(token)存储在Redis中,类似 JSessionId-Session的关系,用户登录后每次请求在Header中携带jwt
如果你是使用session的话,也完全可以借鉴本文的思路,只是代码上需要加些改动
两种实现思路
比较时间戳
维护一个 username: jwtToken 这样的一个 key-value 在Reids中, Filter逻辑如下:
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<String> 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(); if (tokenUnixTime.compareTo(redisTokenUnixTime) > 0) { bucket.set(token); } else { userService.logout(token); sendJsonResponse(response, 4001, "您的账号已在其他设备登录"); return false; } } return true; } }
队列踢出
public class QueueKickOutFilter extends KickOutFilter { private boolean kickoutAfter = false; 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<String> deque = redissonClient.getDeque(userKey); if (!deque.contains(token) && currentSession.isKickout() == false) { deque.push(token); } while (deque.size() > maxSession) { String kickoutSessionId; if (kickoutAfter) { kickoutSessionId = deque.removeFirst(); } else { kickoutSessionId = deque.removeLast(); } try { RBucket<UserBO> bucket = redissonClient.getBucket(kickoutSessionId); UserBO kickoutSession = bucket.get(); if (kickoutSession != null) { kickoutSession.setKickout(true); bucket.set(kickoutSession); } } catch (Exception e) { } } if (currentSession.isKickout()) { try { userService.logout(token); sendJsonResponse(response, 4001, "您的账号已在其他设备登录"); } 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; } }
比较两种方法
1. 第一种方法逻辑简单粗暴, 只维护一个key-value 不需要使用锁,非要说缺点的话没有第二种方法灵活。
2. 第二种方法我很喜欢,代码很优雅灵活,但是逻辑相对麻烦一些,而且为了保证线程安全地操作队列,要使用分布式锁。目前我们项目中使用的是第一种方法
演示
下载地址:
gitee.com/yintianwen7/taven-springboot-learning/tree/master/login-control
1. 运行项目,访问localhost:8887 demo中没有存储用户信息,随意输入用户名密码,用户名相同则被踢出
2. 访问 localhost:8887/index.html 弹出用户信息, 代表当前用户有效
3. 另一个浏览器登录相同用户名,回到第一个浏览器刷新页面,提示被踢出
4. application.properties中选择开启哪种过滤器模式,默认是比较时间戳踢出,开启队列踢出 queue-filter.enabled=true。