static ZookeeperRegisterServiceImpl getInstance() {
        if (instance == null) {
            synchronized (ZookeeperRegisterServiceImpl.class) {
                if (instance == null) {
                    instance = new ZookeeperRegisterServiceImpl();
                }
            }
        }
        return instance;
    }
@Test
    public void getInstance() {
        ZookeeperRegisterServiceImpl service1 = ZookeeperRegisterServiceImpl.getInstance();
        Assertions.assertEquals(service1, service);
    }