关于JdbcTemplate的queryForObject连续查询同一内容会导致nullPointerException

[Viking18]

代码如下

 public User getUserByName(String username) {
        DataSourceRouterManager.setCurrentDataSourceKey("primary");
        try {
            return (User) jdbcTemplate.queryForObject(
                    "select id,username,password,salt from user_table where username=? ",
                    new Object[]{username}, new RowMapper() {
                        @Override
                        public Object mapRow(ResultSet rs, int rowNum)
                                throws SQLException {
                            User user = new User();
                            user.setUsername((rs.getString("username")));
                            user.setPassword(rs.getString("password"));
                            user.setSalt(rs.getString("salt"));
                            user.setId(rs.getInt("id"));
                            return user;
                        }
                    }
            );
        }
// 如果表中无对应记录，queryForObject会抛出异常，捕获后返回空对象
        catch (EmptyResultDataAccessException e){
            return null;
        }
    }

test方法如下

public String test() {
        String res = "";
        String name = "viking";
        User user= userDao.getUserByName(name);
        User user1 = userDao.getUserByName(name);
        res += user.toString()+user1.toString();
        return res  ;
    }

结果在user.setUsername((rs.getString("username")));行抛出空指针异常

另外如果使用queryForMap则不会这样

public User getUserByName(String username) {
        DataSourceRouterManager.setCurrentDataSourceKey("primary");
        try {
            Map<String, Object> map = jdbcTemplate.queryForMap(
                    "select id,username,password,salt from user_table where username=? ",
                    new Object[]{username});
            User user = new User();
            user.setUsername(map.get("username").toString());
            user.setPassword(map.get("password").toString());
            user.setSalt(map.get("salt").toString());
            user.setId(Integer.parseInt(map.get("id").toString()));
            return user;
        }
        catch (EmptyResultDataAccessException e){
            return null;
        }
    }