SQL(MY SQL):
create table tgroup (
? group_id int not null auto_increment,
? name varchar(16) not null default ′′,
? primary key? (group_id)
) type=innodb;
create table trole (
? role_id int not null auto_increment,
? name varchar(16) not null default ′′,?
? primary key? (role_id)
) type=innodb;
create table tgroup_role (
? group_id int not null,
? role_id int not null,
? primary key(group_id, role_id),
? index (group_id),
? foreign key (group_id) references tgroup(group_id),
? index (role_id),
? foreign key (role_id) references trole(role_id)
) type=innodb;
Group 類：
package ivan.hibernate.many2many;
public class Group {
? ?private int id;
? ?private String name;
? ?private Set roles = new HashSet();
?? ...
}
Group.hbm.xml：
<hibernate-mapping>
??? <class name="ivan.hibernate.many2many.Group" table="tgroup">
??????? <id name="id" column="group_id" unsaved-value="0">
??????????? <generator class="increment"/>
??????? </id>
??????? <property name="name" type="string"/>??????
??????? <set name="roles"
???????????? table="tgroup_role"
???????????? cascade="save-update">????????????
???????????? <key column="group_id"/>
???????????? <many-to-many class="ivan.hibernate.many2many.Role"
?????????????????????????? column="role_id"/>
?????? </set>
??? </class>
</hibernate-mapping>
Role 類：
package ivan.hibernate.many2many;
public class Role {
?? private int id;
? ?private String name;
? ?private Set groups = new HashSet();
?? ...
}
Role.hbm.xml：
<hibernate-mapping>
??? <class name="ivan.hibernate.many2many.Role" table="trole">
??????? <id name="id" column="role_id" unsaved-value="0">
??????????? <generator class="increment"/>
??????? </id>
??????? <property name="name" type="string"/>??????
??????? <set name="groups"
???????????? table="tgroup_role"
????????????
inverse="true"
???????????? cascade="save-update">????????????
???????????? <key column="role_id"/>
???????????? <many-to-many class="ivan.hibernate.many2many.Group"
?????????????????????????? column="group_id"/>
??</set>
??? </class>
</hibernate-mapping>
hibernate.cfg.xml 同前面的例子差不多。
public class Test {
?
?public static void main(String[] args) throws HibernateException {
????
??Role role1 = new Role();?
??role1.setName("Role1");
??Role role2 = new Role();
??role2.setName("Role2");
??Role role3 = new Role();
??role3.setName("Role3");
??Group group1 = new Group();
??group1.setName("group1");
??Group group2 = new Group();
??group2.setName("group2");
??Group group3 = new Group();
??group3.setName("group3");
??group1.getRoles().add(role1);
??group1.getRoles().add(role2);
??group2.getRoles().add(role2);
??group2.getRoles().add(role3);
??group3.getRoles().add(role1);
??group3.getRoles().add(role3);
??role1.getGroups().add(group1);
??role1.getGroups().add(group3);
??role2.getGroups().add(group1);
??role2.getGroups().add(group2);
??role3.getGroups().add(group2);
??role3.getGroups().add(group3);
?
??SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
??Session session = sessionFactory.openSession();
??Transaction tx= session.beginTransaction();
??session.save(role1);
??session.save(role2);
??session.save(role3);
??session.save(group1);
??session.save(group2);
??session.save(group3);
??tx.commit();
??session.close();
??sessionFactory.close();
?}
}