Hibernate ORM - 一对一连接表关联关系

　　对于一对一关联关系的建立，除了前面讲的方式，即将关联关系由某一方维持外，还可以采用另外一种基于第三张表的关联关系方式，即除去两方各自映射的数据表外，再在数据库中建立第三张表用以维持两者的一对一关联关系。下面来看看这是如何实现的吧。

　　一。Husband

package com.orm.model;

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

    private Wife wife;

    public Husband() {
    }

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

    public Husband(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.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"/>

        <join table="couple">
            <key column="husbandid"/>
            <many-to-one name="wife" column="wifeid" class="com.orm.model.Wife" cascade="all"/>
        </join>
    </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;
    }

    public Wife() {
    }

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

<?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"/>

        <one-to-one name="husband" class="com.orm.model.Husband"/>
    </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;

/**
 * Created by IntelliJ IDEA.
 * User: Zhong Gang
 * Date: 10/18/11
 * Time: 3:40 PM
 */
public class HibernateOneToOneTest 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 wife = new Wife("wife");
        Husband husband = new Husband("husband", wife);
        coupleService.saveOrUpdate(husband);
    }
}

　　测试结果截图

　　 Hibernate ORM - 一对一连接表关联关系

　　这里讲解的是一对一双向的连接表关联关系的建立，如果想要实现单向的关联关系，那么在删除代码中对对方引用的同时需要删除配置文件中的one-to-one元素。最后附上源码以供参考。