public List<Post> selectByArtId(String id) {
   if (id == null) return null;
   Long artId = Long.parseLong(id);
   PostExample e = new PostExample();
   e.createCriteria().andArtIdEqualTo(artId);
   return postMapper.selectByExample(e);
 }
 public void save(Post post) {
   post.setStatus(1);
   post.setAddTime(new Date());
   post.setUpdateTime(new Date());
   post.setUserId(AppContext.getUser().getRecId());
   postMapper.insert(post);
 }