本文主要是介绍Hibernate中的manytomany映射实例一，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
转自：http://blog.csdn.net/woshisap/article/details/6448774
2：User的配置文件为：
<hibernate-mapping >
<class name="com.bjsxt.hibernate.User" table="t_user">
<id name="id">
<generator class="native"/>
</id>
<property name="name"/>
<set name="roles" table="t_user_role">
<key column="userid"/>
<many-to-many class="com.bjsxt.hibernate.Role" column="roleid"/>
</set>
</class>
</hibernate-mapping>
Role的配置文件为：
<hibernate-mapping >
<class name="com.bjsxt.hibernate.Role" table="t_role">
<id name="id">
<generator class="native"/>
</id>
<property name="name"/>
<set name="users" table="t_user_role" order-by="userid">
<key column="roleid"/>
<many-to-many class="com.bjsxt.hibernate.User" column="userid"/>
</set>
</class>
</hibernate-mapping>
3：测试程序为：
public void testSave1(){ //首先保存Role，再保存User
Session session = null;
try{
session = HibernateUtils.getSession();
session.beginTransaction();
Role r1 = new Role();
r1.setName("数据录入人员");
session.save(r1);
Role r2 = new Role();
r2.setName("商务主管");
session.save(r2);
Role r3 = new Role();
r3.setName("大区经理");
session.save(r3);
User u1 = new User();
u1.setName("10");
Set u1Roles = new HashSet();
u1Roles.add(r1);
u1Roles.add(r2);
u1.setRoles(u1Roles);
User u2 = new User();
u2.setName("aaa");
Set u2Roles = new HashSet();
u2Roles.add(r2);
u2Roles.add(r3);
u2.setRoles(u2Roles);
User u3 = new User();
u3.setName("kjj");
Set u3Roles = new HashSet();
u3Roles.add(r1);
u3Roles.add(r2);
u3Roles.add(r3);
u3.setRoles(u3Roles);
session.save(u1);
session.save(u2);
session.save(u3);
session.getTransaction().commit();
}catch(Exception e){
e.printStackTrace();
session.getTransaction().rollback();
}finally{
HibernateUtils.closeSession(session);
}
}
//首先加载User，根据User来加载Role
public void testLoad1(){
Session session = null;
try{
session = HibernateUtils.getSession();
session.beginTransaction();
User user = (User)session.load(User.class,1);
System.out.println(user.getName());
for(Iterator iter = user.getRoles().iterator();iter.hasNext();){
Role role = (Role)iter.next();
System.out.println("role.name"+role.getName());
}
session.getTransaction().commit();
}catch(Exception e){
e.printStackTrace();
session.getTransaction().rollback();
}finally{
HibernateUtils.closeSession(session);
}
}
//首先加载Role，再根据Role来加载User
public void testLoad2(){
Session session = null;
try{
session = HibernateUtils.getSession();
session.beginTransaction();
Role role = (Role) session.load(Role.class,1);
System.out.println("role.name"+role.getName());
for(Iterator iter = role.getUsers().iterator();iter.hasNext(); ){
User student = (User)iter.next();
System.out.println("student.name:"+student.getName());
}
session.getTransaction().commit();
}catch(Exception e){
e.printStackTrace();
session.getTransaction().rollback();
}finally{
HibernateUtils.closeSession(session);
}
}
}
总结：
hibernate多对多关联映射(双向User<----->Role)
具体映射方式：
<set name="roles" table="t_user_role">
<key column="userid"/>
<many-to-many class="com.bjsxt.hibernate.Role" column="roleid"/>
</set>
table属性值必须和单向关联中的table属性值一致
<key>中column属性值要和单向关联中<many-to-many>标签中的column属性值一致
<many-to-many>中的column属性值要与单向关联中<key>标签的column属性值一致
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