@RequestMapping(value = "/tweet/comment", method = RequestMethod.POST)
  public void comment(@RequestBody Message message) {

    Tweet tweet = tweetRepo.findOne(message.getTid());
    tweet.setCommentCount(tweet.getCommentCount() + 1);
    tweetRepo.saveAndFlush(tweet);

    // 保存评论
    UserTweet userTweet = new UserTweet();
    userTweet.setUid(message.getUid());
    userTweet.setTid(message.getTid());
    userTweet.setUserTweetType(UserTweet.UserTweetType.COMMENT);
    userTweetRepo.saveAndFlush(userTweet);

    message.setMessageType(Message.MessageType.COMMENT);
    message.setTime(Utils.getTime());
    message.setDate(System.currentTimeMillis());
    Utils.message(messageRepo.saveAndFlush(message));
  }