需要將你的程式碼改成如下：

//通過使用者id查詢
    @RequestMapping("/getUserById/{id}")
    @ResponseBody
    public User getUserById(@PathVariable Integer id){
        String sql = "select * from user where id="+id;
        RowMapper<User> mapper = new RowMapper<User>() {
            @Override
            public
 
 User mapRow(ResultSet rs, int i) throws SQLException {
                User user = new User();
                user.setId(rs.getLong("id"));
                user.setName(rs.getString("name"));
                user.setAge(rs.getInt("age"));
                return user;
            }
        };

        User user = jdbcTemplate.queryForObject(sql, mapper);
        return
 
 user;
    }

其中的實體類根據具體的情況來定。