（一）基于注解的配置方式：（通过雇主和雇员来解释多对多双向关联）
通过@ManyToMany注解可定义的多对多关联. 同时,你也需要通过注解@JoinTable描述关联表和关联条件. 如果是双向关联,其中一段必须定义为owner,另一端必须定义为inverse(在对关联表进行更新操作时这一端将被忽略):
@Entity public class Employer implements Serializable { @ManyToMany @JoinTable( name="EMPLOYER_EMPLOYEE", joinColumns=@JoinColumn(name="Employer_ID"), inverseJoinColumns=@JoinColumn(name="Employee_ID") ) public Collection getEmployees() { return employees; } ... } @Entity public class Employee implements Serializable { @ManyToMany(mappedBy = "employees") //参数值为Employer中的getEmployees中get后的值：employees public Collection getEmployers() { return employers; } }被关联端不必也不能描述物理映射: 只需要一个简单的mappedBy参数,该参数包含了主体端的属性名,这样就绑定双方的关系.
（二）基于xml的配置方式：
Student.hbm.xml的配置：
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="hibernate.Student"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> <set name="teachers" table="t_s"> <key column="student_id"></key> <many-to-many class="hibernate.Teacher" column="teacher_id"/> </set> </class> </hibernate-mapping>
Teacher.hbm.xml的配置：
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="com.bjsxt.hibernate.Teacher"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> <set name="students" table="t_s"> <key column="teacher_id"></key> <many-to-many class="com.bjsxt.hibernate.Student" column="student_id"/> </set> </class> </hibernate-mapping>
