oracle+ mybatis 插入数据时返回插入uuid

oracle使用sys_guid()来自动获取uuid时，需要把此id返回

<insert id="addTask" parameterType="Task"> 
	<selectKey resultType="String" keyProperty="uuid" order="BEFORE">
      		SELECT sys_guid() FROM DUAL
      </selectKey>
	insert into t_zone_task values(#{uuid}, #{title}, #{author}, #{subjectId}, sysdate, #{duration}, #{state})
</insert>

测试代码：

public void addTask(Task task) {
		System.out.println("before:" + task.getUuid());
		taskMapper.addTask(task);
		System.out.println("after:" + task.getUuid());
	}