code: public static void start(String connectionStr) {
          synchronized (zkConnectionStartStopLock) {
              if (connected.get()) {
                  LOG.info("zkConnection已经启动，不再重复启动");
                  return;
              }
              try {
                  RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
                  client = CuratorFrameworkFactory.newClient(connectionStr, retryPolicy);
                  client.start();
                  LOG.info("阻塞直到与zookeeper连接建立完毕！");
                  client.blockUntilConnected();
              } catch (Throwable e) {
                  LOG.error(e);
              } finally {
                  connected.set(true);
              }
          }
      }
docs: 仅供内部测试使用