jdbc 预编译处理 和spring返回自增主键值

final String INSERT_SQL = "insert into gtable(username,password) values(?,?)"; 
        KeyHolder keyHolder = new GeneratedKeyHolder(); 
    int lines=jdbcTemplate.update(new PreparedStatementCreator() {//创建一个PreparedStatement实例
            public PreparedStatement createPreparedStatement( 
                    Connection connection) throws SQLException {
                PreparedStatement ps = connection.prepareStatement(INSERT_SQL,
                        new String[] { "id" });//通过Connection创建绑定自增值的PreparedStatement
                ps.setString(1, username);//绑定参数时，序号从1开始而不是0
                ps.setString(2, password);
                return ps;
            }
        }, keyHolder);
Number current_key = keyHolder.getKey();
System.out.println("修改行数："+lines);
System.out.println("当前主键："+current_key);