public class Lock {
 
    private static final String prefix = "lock/";  // 同步锁参数前缀
 
    private ConsulClient consulClient;
    private String sessionName;
    private String sessionId = null;
    private String lockKey;
 
    /**
 *
 * @param consulClient
 * @param sessionName 同步锁的session名称
 * @param lockKey 同步锁在consul的KV存储中的Key路径，会自动增加prefix前缀，方便归类查询
 */
    public Lock(ConsulClient consulClient, String sessionName, String lockKey) {
        this.consulClient = consulClient;
        this.sessionName = sessionName;
        this.lockKey = prefix + lockKey;
    }
 
    /**
 * 获取同步锁
 *
 * @param block 是否阻塞，直到获取到锁为止
 * @return
 */
    public Boolean lock(boolean block) {
        if (sessionId != null) {
            throw new RuntimeException(sessionId + " - Already locked!");
        }
        sessionId = createSession(sessionName);
        while(true) {
            PutParams putParams = new PutParams();
            putParams.setAcquireSession(sessionId);
            if(consulClient.setKVValue(lockKey, "lock:" + LocalDateTime.now(), putParams).getValue()) {
                return true;
            } else if(block) {
                continue;
            } else {
                return false;
            }
        }
    }
 
    /**
 * 释放同步锁
 *
 * @return
 */
    public Boolean unlock() {
        PutParams putParams = new PutParams();
        putParams.setReleaseSession(sessionId);
        boolean result = consulClient.setKVValue(lockKey, "unlock:" + LocalDateTime.now(), putParams).getValue();
        consulClient.sessionDestroy(sessionId, null);
        return result;
    }
 
    /**
 * 创建session
 * @param sessionName
 * @return
 */
    private String createSession(String sessionName) {
        NewSession newSession = new NewSession();
        newSession.setName(sessionName);
        return consulClient.sessionCreate(newSession, null).getValue();
    }
 
}

public class TestLock {
 
    private Logger logger = Logger.getLogger(getClass());
 
    @Test
    public void testLock() throws Exception {
        new Thread(new LockRunner(1)).start();
        new Thread(new LockRunner(2)).start();
        new Thread(new LockRunner(3)).start();
        new Thread(new LockRunner(4)).start();
        new Thread(new LockRunner(5)).start();
        Thread.sleep(200000L);
    }
  
    class LockRunner implements Runnable {
 
        private Logger logger = Logger.getLogger(getClass());
        private int flag;
 
        public LockRunner(int flag) {
            this.flag = flag;
        }
 
        @Override
        public void run() {
            Lock lock = new Lock(new ConsulClient(), "lock-session", "lock-key");
            try {
                if (lock.lock(true)) {
                    logger.info("Thread " + flag + " start!");
                    Thread.sleep(new Random().nextInt(3000L));
                    logger.info("Thread " + flag + " end!");
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                lock.unlock();
            }
        }
    }
  
}