ibatis新增后返回String类型的主键

//sqlmap?

<insert id="insertTask" parameterkeyProperty="mainid">
???select NEWID() as mainid
??????? </selectKey>
??INSERT INTO
??Course_Task
??(MainID,Task_CourseID,Task_Content,Task_TurnedDate,Task_CreateDate,
??Task_isRead,Task_RealName,Task_saveurl,Task_filetype,Task_filesize,Task_uploaduserid,Course_ContentID)
??VALUES
??(#mainid#,#courseID#,#content#,#turnedDate#,getDate(),
??#isRead#,#realName#,#saveurl#,#filetype#,#filesize#,#uploaduserid#,#coursecontentID#)
?</insert>

?

?

//dao

?public Object save(Object obj) {
??// TODO Auto-generated method stub
??return (String)this.getSqlMapClientTemplate().insert("insertTask", obj);
?}

?

?

//strusts2 action

String mainid=(String)taskService.save(t);?//获取新插入的表的主键