Hibernate多对多

先建立两个类：Teacher和Student

public class Teacher {      PRivate int id;      private String name;      private Set<Student> students;          ……//set/get方法  }  
public class Student {      private int id;      private String name;      private Set<Teacher> teachers;          ……//set/get方法  } 多对多关系的建立，在两个类中，首先要各自包含对方的属性，由于是多对多，所以是一个集合对象。这个是建立映射关系的基础。
然后就是对应的映射文件了：
Teacher.hbm.xml：  <hibernate-mapping package="com.it.domain">            <class name="Teacher">          <id name="id">              <generator class="native"/>          </id>          <property name="name"/>          <set name="students" table="teacher_student">             <key column="teacher_id"/>             <many-to-many class="Student" column="student_id"/>          </set>      </class>        </hibernate-mapping> Student.hbm.xml：  <hibernate-mapping package="com.it.domain">            <class name="Student">          <id name="id">              <generator class="native"/>          </id>          <property name="name"/>          <set name="teachers" table="teacher_student">              <key column="student_id"/>              <many-to-many class="Teacher" column="teacher_id"/>          </set>      </class>        </hibernate-mapping>