SpringBoot 并发登录人数控制的实现方法

2019-11-26 08:59:33

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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

SpringBoot
JWT
Filter
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();      // token > redisToken 则覆盖      if (tokenUnixTime.compareTo(redisTokenUnixTime) > 0) {        bucket.set(token);      } else {        // 注销当前token        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 {  /**   * 踢出之前登录的/之后登录的用户 默认踢出之前登录的用户   */  private boolean kickoutAfter = false;  /**   * 同一个帐号最大会话数 默认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<String> deque = redissonClient.getDeque(userKey);      // 如果队列里没有此token，且用户没有被踢出；放入队列      if (!deque.contains(token) && currentSession.isKickout() == false) {        deque.push(token);      }      // 如果队列里的sessionId数超出最大会话数，开始踢人      while (deque.size() > maxSession) {        String kickoutSessionId;        if (kickoutAfter) { // 如果踢出后者          kickoutSessionId = deque.removeFirst();        } else { // 否则踢出前者          kickoutSessionId = deque.removeLast();        }        try {          RBucket<UserBO> bucket = redissonClient.getBucket(kickoutSessionId);          UserBO kickoutSession = bucket.get();          if (kickoutSession != null) {            // 设置会话的kickout属性表示踢出了            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()) {        // 会话被踢出了        try {          // 注销          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