hibernate怎么样实现自关联多对多

public class User{
//.........基本属性
private Set<User> follow;//用户关注
private Set<User> fans;//粉丝列表
//getter and setter
}

<hibernate-mapping>      <class name=”bean.Student” table=”students”>          <id name=”id” column=”id” type=”long”>              <generator class=”increment”></generator>          </id>          <property name=”name” column=”name” type=”string”></property>          <set name=”courses” table=”students_courses” cascade=”save-update”>               <key column=”student_id”></key>              <many-to-many class=”bean.Course” column=”course_id”></many-to-many>          </set>      </class>  </hibernate-mapping>