SpringBoot 实现并发登录人数控制

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mb5fe94d44e2c3a 2021-06-19 16:13:20

文章标签 java 文章分类 Java 后端开发

今天跟大家分享SpringBoot 实现并发登录人数控制的知识。

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

SpringBoot 实现并发登录人数控制_java

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

SpringBoot 实现并发登录人数控制_java_02

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;    }
}