java.sql.SQLException: Generated keys not requested. You need to specify Statement.RETURN_GENERATED_KEYS to Statement.executeUpdate(), Statement.executeLargeUpdate() or Connection.prepareStatement().
经过检查发现从5.1.7版本之后的mysql-connector增加了返回GeneratedKeys的条件，如果需要返回GeneratedKeys，则PreparedStatement需要显式添加一个参数Statement.RETURN_GENERATED_KEYS，如下：
connection = JDBCUtil.getConnection();
preparedStatement = connection.prepareStatement(sql.toString(),Statement.RETURN_GENERATED_KEYS);