if there are more than two server run with the same system code
            and call the save method at the same time ,it will be result of hibernate
            error!because hibernate get the max id for ganerator and store it in
            cache for next time using.so one server will get the expired id if another
            server change the database following.
            befroe save object,hibernate will excute this sql after the server start up once:
             Hibernate: select max(ID) from TB_LOG
            TB_LOG is my log table.