spring中EmptyResultDataAccessException

org.springframework.dao.EmptyResultDataAccessException: Incorrect result size: expected 1, actual 0

使用template.queryForObject时发生异常

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@Nullable
   public static <T> T nullableSingleResult(@Nullable Collection<T> results) throws IncorrectResultSizeDataAccessException {
       if (CollectionUtils.isEmpty(results)) {
           throw new EmptyResultDataAccessException(1);
       } else if (results.size() > 1) {
           throw new IncorrectResultSizeDataAccessException(1, results.size());
       } else {
           return results.iterator().next();
       }
   }

上面是nullableSingleResult方法中的源码，当results为空时，抛出EmptyResultDataAccessException

当返回值大小大于1时，抛出IncorrectResultSizeDataAccessException异常

所以在使用template.queryForObject时要进行异常处理

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public static User login(User loginuser) {
        //查询数据库
        String sql = "select *  from user where username = ? and password = ?";
        User resUser = null;
        try {
            resUser = template.queryForObject(sql, new BeanPropertyRowMapper<User>(User.class), loginuser.getUsername(), loginuser.getPassword());
            return resUser;
        }catch (EmptyResultDataAccessException e) {
            return null;
        }
    }