public void close() {
        if (closed) {
            return;
        }
        closed = true;
        try {
            doClose();
        } catch (Exception e) {
            logger.warn(e.getMessage(), e);
        }
    }
@author Robert HG (254963746@qq.com) on 7/8/14.
lts-core/src/main/java/com/github/ltsopensource/zookeeper/support/AbstractZkClient.java