Hibernate ORM - 一对多双向连接表关联关系

 

 

　　对于一对多的关联关系，除去上一单讲的在多方对应的数据表中增加一个外键字段，用来标识一方外，还有一种做法就是将两者的关联关系提取出来，单独建立一个第三方数据表用以维护两者的一对多关联关系。

 

　　一。Husband

 

package com.orm.model;

import java.util.List;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 10/18/11
 * Time: 3:23 PM
 */
public class Husband extends DomainObject {
    private String name;

    private List<Wife> wifes;

    public Husband(String name, List<Wife> wifes) {
        this.name = name;
        this.wifes = wifes;
    }
}

 

<?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">

<hibernate-mapping default-access="field">

    <class name="com.orm.model.Husband" table="husband">
        <id name="id" column="id" type="java.lang.Integer">
            <generator class="native"/>
        </id>
        <property name="name" column="name" type="java.lang.String"/>

        <bag name="wifes" table="couple" cascade="all">
            <key column="husbandid"/>
            <many-to-many column="wifeid" class="com.orm.model.Wife"/>
        </bag>
    </class>

</hibernate-mapping>

 

 

　　二。Wife

 

package com.orm.model;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 10/18/11
 * Time: 3:23 PM
 */
public class Wife extends DomainObject {
    private String name;

    private Husband husband;

    public Wife(String name) {
        this.name = name;
    }
}

 

<?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">

<hibernate-mapping default-access="field">

    <class name="com.orm.model.Wife" table="wife">
        <id name="id" column="id" type="java.lang.Integer">
            <generator class="native"/>
        </id>
        <property name="name" column="name" type="java.lang.String"/>

        <join table="couple" optional="true">
            <key column="wifeid"/>
            <many-to-one name="husband" column="husbandid" class="com.orm.model.Husband"/>
        </join>
    </class>

</hibernate-mapping>

 

　　三。测试代码

 

package com.orm;

import com.orm.model.Husband;
import com.orm.model.Wife;
import com.orm.service.CoupleService;
import junit.framework.TestCase;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 10/18/11
 * Time: 3:40 PM
 */
public class HibernateOneToManyTest extends TestCase {
    private CoupleService coupleService;

    @Override
    public void setUp() throws Exception {
        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:testDataSource.xml");
        coupleService = (CoupleService) context.getBean("coupleService");
    }

    public void testOneToOne() throws Exception {
        Wife wife1 = new Wife("wife1");
        Wife wife2 = new Wife("wife2");
        Wife wife3 = new Wife("wife3");

        List<Wife> wifes = new ArrayList<Wife>();
        wifes.add(wife1);
        wifes.add(wife2);
        wifes.add(wife3);

        Husband husband = new Husband("husband", wifes);
        coupleService.saveOrUpdate(husband);
    }
}

 

　　测试结果及截图

 

　　

 

　　

 

　　

 

　　这是一个一对多的双向连接表关联关系，如果想要实现单向的连接表关联关系，那么需要在删除对方引用的同时，删除其配置文件中的join或集合元素。附上源代码以供参考。