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();
    }

}