public class Student {

     private int id;

     private String name;

     private Set<Teacher> teachers = new HashSet<Teacher>();

 }

 public class Teacher {

     private int id;

     private String name;

     private Set<Student> students = new HashSet<Student>();

 }

 <hibernate-mapping package="entity">

     <class name="Student">

         <id name="id">

             <generator class="native"/>

         </id>

         <property name="name"/>

         <!--

             <set>标签的table属性：    配置关系表的名称

             <key>标签的column属性：    当前实体对应数据库表的外键字段名

             <many-to-many>标签表示多对多关系，属性：

                 class属性：    表示对方的类名

                 column属性： 表示对方的表在关系表中的外键字段名

         -->

         <set name="teachers" table="StudentTeacher" cascade="save-update">

             <key column="studentId"/>

             <many-to-many class="Teacher" column="teacherId" />

         </set>

     </class>

 </hibernate-mapping>

 <hibernate-mapping package="entity">

     <class name="Teacher">

         <id name="id">

             <generator class="native"/>

         </id>

         <property name="name"/>

         <set name="students"  table="StudentTeacher" cascade="save-update">

             <key column="teacherId"/>

             <many-to-many class="Student" column="studentId" />

         </set>

     </class>

 </hibernate-mapping>