在Hibernate中配置多对多连接表

接前文在Hibernate中配置一对多连接表

其中表roomusers更改如下：


create table ROOMUSERS(


USERID NUMBER(4),


ROOMID NUMBER(4) not null


);

映射文件配置如下：

Room.hbm.xml


<?xml version="1.0" encoding="utf-8"?>


<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"


"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">


<!--


Mapping file autogenerated by MyEclipse Persistence Tools


-->


<hibernate-mapping package="com.cosmow.hibernatedemo2.entity">


<class name="Room" table="ROOM" schema="STORE">


<id name="id" type="java.lang.Long">


<column name="ID" precision="4" scale="0" />


<!-- Oracle数据库增长方式序列 -->


<generator class="sequence">


<param name="sequence">ROOM_SEQ</param>


</generator>


</id>


<!-- 映射roomnumber属性 -->


<property name="roomnumber" type="java.lang.String">


<column name="ROOMNUMBER" length="11" not-null="true" />


</property>


<!-- 映射name属性 -->


<property name="name" type="java.lang.String">


<column name="NAME" length="32" not-null="true" />


</property>


<!-- 通过连接表的多端，因此需要table属性为roomusers -->


<set name="users" cascade="all" table="roomusers">


<!-- 该key的字段为连接表中的字段，作为外键 -->


<key column="roomid" />


<!-- 配置多对多 -->


<many-to-many class="Userinfo" column="userid" />


</set>


</class>


</hibernate-mapping>



Userinfo.hbm.xml


<?xml version="1.0" encoding="utf-8"?>


<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"


"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">


<!--


Mapping file autogenerated by MyEclipse Persistence Tools


-->


<hibernate-mapping package="com.cosmow.hibernatedemo2.entity">


<class name="Userinfo" table="USERINFO" schema="STORE">


<id name="id" type="java.lang.Long">


<column name="ID" precision="4" scale="0" />


<!-- Oracle数据库增长方式序列 -->


<generator class="sequence">


<param name="sequence">USERINFO_SEQ</param>


</generator>


</id>


<property name="name" type="java.lang.String">


<column name="NAME" length="32" not-null="true" />


</property>


<property name="sex" type="java.lang.String">


<column name="SEX" length="2" />


</property>


<set name="rooms" cascade="all" table="roomusers">


<key column="userid" />


<many-to-many class="Room" column="roomid" />


</set>


</class>


</hibernate-mapping>



测试代码如下：




/** *//**


* Demo.java


*


* Copyright 2008. All Rights Reserved.


*/


package com.cosmow.hibernatedemo2.demo;




import java.util.HashSet;


import java.util.Iterator;


import java.util.Set;




import org.hibernate.Session;


import org.hibernate.Transaction;




import com.cosmow.HibernateSessionFactory;


import com.cosmow.hibernatedemo2.entity.Room;


import com.cosmow.hibernatedemo2.entity.Userinfo;






/** *//**


* TODO


*


* Revision History


*


* 2008-7-11,Cosmo,created it


*/




public class Demo

{






public void test()

{


//第一个room实体


Room room = new Room();


room.setName("cosmoHome");


room.setRoomnumber("001");




//第二个room实体


Room room2 = new Room();


room2.setName("Home2");


room2.setRoomnumber("002");




//第一个user实体


Userinfo user = new Userinfo();


user.setName("cosmo");


user.setSex("M");




//第二个user实体


Userinfo user2 = new Userinfo();


user2.setName("winnie");


user2.setSex("F");




//创建第二个user实体与第二个room实体的关系，通过连接表维护关系


Set<Room> roomSet = new HashSet<Room>();


roomSet.add(room2);


user2.setRooms(roomSet);




//创建第一个room实体与第一、第二个user实体的关系，通过连接表维护关系


//添加user实体到集合userSet


Set<Userinfo> userSet = new HashSet<Userinfo>();


userSet.add(user);


userSet.add(user2);


room.setUsers(userSet);




// 启动Session


Session session = HibernateSessionFactory.getSession();


// 启动事务


Transaction tx = session.beginTransaction();


// 持久化room实体


//此时将更新表room和userinfo以及维护关系的roomusers表


session.save(room);


tx.commit();


HibernateSessionFactory.closeSession();




// 启动Session


session = HibernateSessionFactory.getSession();


// 启动事务


tx = session.beginTransaction();




//获取Room实体以成为持久化状态，此时将获取room表的所有字段信息


Room roomF1 = (Room)session.get(Room.class, room.getId());




//通过外连接roomusers获取userinfo表对应字段信息


Iterator<Userinfo> iF1 = roomF1.getUsers().iterator();




while(iF1.hasNext())

{


Userinfo userF = iF1.next();


System.out.println(userF.getId());


System.out.println(userF.getName());


System.out.println(userF.getSex());


}




Room roomF2 = (Room)session.get(Room.class, room2.getId());




Iterator<Userinfo> iF2 = roomF2.getUsers().iterator();




while(iF1.hasNext())

{


Userinfo userF = iF2.next();


System.out.println(userF.getId());


System.out.println(userF.getName());


System.out.println(userF.getSex());


}




tx.commit();


HibernateSessionFactory.closeSession();


}






public static void main(String[] args)

{


Demo demo = new Demo();


demo.test();