用GeneratedKeyHolder获得新建数据主键值

 public User createUser(final User user) {
        final String sql = "insert into sys_users(username, password, salt, locked) values(?,?,?, ?)";
        GeneratedKeyHolder keyHolder = new GeneratedKeyHolder();
        jdbcTemplate.update(new PreparedStatementCreator() {
            public PreparedStatement createPreparedStatement(Connection connection) throws SQLException {
                PreparedStatement psst = connection.prepareStatement(sql, new String[]{"id"});
                psst.setString(1, user.getUsername());
                psst.setString(2, user.getPassword());
                psst.setString(3, user.getSalt());
                psst.setBoolean(4, user.getLocked());
                return psst;
            }
        }, keyHolder);
        user.setId(keyHolder.getKey().longValue());
        return user;
    }