/*添加评论*/
 public void addComment(Comment comment, Video video) {
   commentDao.save(comment);
   video.setCommentCount(video.getCommentCount() + 1);
   videoDao.update(video);
 }
 /*获取视频的评论*/
 public List<Comment> findComment(Video video) {
   Object[] params = new Object[] {video};
   Map<String, String> orderBy = new LinkedHashMap<String, String>();
   orderBy.put("o.time", Const.ODER_DESC);
   return commentDao.findByCondition("and o.video=?", params, orderBy, false);
 }