@Override
 public Role get(long id) {
   SqlSession sqlSession = sqlSessionFactory.openSession();
   Role role = null;
   try {
     role = roleMapper.select(id);
   } finally {
     sqlSession.close();
   }
   return role;
 }
 @Override
 public Role getByName(String name) {
   SqlSession sqlSession = sqlSessionFactory.openSession();
   Role role = null;
   try {
     role = roleMapper.selectByName(name);
   } finally {
     sqlSession.close();
   }
   return role;
 }
 @Override
 public ListPage<Role> list(long start, long size) {
   SqlSession sqlSession = sqlSessionFactory.openSession();
   ListPage<Role> page = null;
   try {
     page = new ListPage<>(start, size);
     page.setItems(roleMapper.list(page));
   } finally {
     sqlSession.close();
   }
   return page;
 }