@Override
 public DemoVO saveAccount(DemoVO vo) {
   Demo a = new Demo();
   BeanHelper.copyProperties(a, vo);
   a.save();
   DemoVO copyProperties = BeanHelper.copyProperties(new DemoVO(), a);
   return copyProperties;
 }
 @Override
 public DemoVO getAccountVO(String accountId) {
   return BeanHelper.copyProperties(new DemoVO(), Demo.get(accountId));
 }