浅谈Java基于Consul创建分布式锁

    private ConsulClient consulClient;
    @PostConstruct
    public void init(){
        consulClient = new ConsulClient(consulLockConfig.getHost(),consulLockConfig.getPort());
    }

    /**
     * 创建一个sessionId
     * @param lockName
     * @param ttlSeconds
     * @return
     */
    private String createSession(String lockName,int ttlSeconds){
        NewSession session = new NewSession();
        //session.setBehavior(Session.Behavior.DELETE);
        session.setBehavior(Session.Behavior.RELEASE);
        session.setName("session " + lockName);
        session.setTtl(ttlSeconds + "s");
        return consulClient.sessionCreate(session, null).getValue();
    }

/**
 * 获取锁
 * @param lockName 锁的名称(key)
 * @param ttlSeconds 锁的超时时间
 * @return
 */
private boolean tryLock(String lockName,int ttlSeconds){
	try {
		PutParams putParams = new PutParams();
		String sessionId = createSession(lockName, ttlSeconds);
		SessionIdHolder.setSessionId(sessionId);
		log.info("consul加锁开始(线程:{},锁名称:{},sessionId:{})",Thread.currentThread().getName(), lockName,sessionId);
		putParams.setAcquireSession(sessionId);
		//2.将构件好的LockContext存储在consul中
		String key = consulLockConfig.PREFIX+lockName;
		//加锁成功
		Boolean value = consulClient.setKVValue(key, sessionId, putParams).getValue();
		if(value){
			//开起一个新的线程去执行锁续命--调用看门狗的方式实现
			if(consulLockConfig.isRenewal()){  //如果续期
				new ConsulWatchDog(consulClient).watchSession(sessionId,ttlSeconds);//启动看门狗
			}
			log.info("consul加锁成功(线程:{},锁名称:{},sessionId:{})",Thread.currentThread().getName(), lockName,sessionId);
			return true;
		}else{
			//将sessionId删除
			//consulClient.deleteKVValue(key);
			log.info("consul加锁失败(线程:{},锁名称:{},sessionId:{})",Thread.currentThread().getName(), lockName,sessionId);
			return false;
		}
	}catch (Exception e){
		e.printStackTrace();
		return false;
	}
}

/**
 * 释放锁
 */
public boolean unLock(String lockName){
	//log.info("consul释放锁开始(线程:{},锁名称:{})",Thread.currentThread().getName(),lockName);
	String sessionId = SessionIdHolder.getSessionId();
	try {
		//先根据锁名称找到对应的sessionId   session 是需要进行存储的  现在我们是通过一个lockContnt 假如说业务上不在一个微服务里释放锁 对应的 其他微服务如何获取到这把锁呢
		String key = consulLockConfig.PREFIX+lockName;
		Response<GetValue> kvValue = consulClient.getKVValue(key);
		if(kvValue==null) return false;
		GetValue value = kvValue.getValue();
		if(value==null) return false;
		//log.info("consul释放锁开始(线程:{},锁名称:{},sessionId:{})",Thread.currentThread().getName(),lockName,sessionId);
		PutParams putParams = new PutParams();
		putParams.setReleaseSession(sessionId);
		consulClient.setKVValue(key, sessionId, putParams);
		//String sessionId = value.getDecodedValue();
		consulClient.sessionDestroy(sessionId, null);// key value也会被删除 是使用的DELETE
		//删除对应的 sessionId存储
		//consulClient.deleteKVValue(key);
		log.info("consul释放锁成功(线程:{},锁名称:{},sessionId:{})",Thread.currentThread().getName(),lockName,sessionId);
		return true;
	}catch (Exception e){
		e.printStackTrace();
		log.info("consul释放锁出错(线程:{},锁名称:{},sessionId:{})",Thread.currentThread().getName(),lockName,sessionId);
		return false;
	}
}