4.Hibernate的一对一主键关联映射

 默认cascade属性为true;

 

核心代码：

1.主键生成策略：

<!-- Person的主键来源于idCard, 也就是共享idCard主键 -->
<generator class="foreign">
	<param name="property">idCard</param>
</generator>

2.one-to-one配置

<!-- one-to-one标签的含义，指示hibernate怎样加载它的关联对象，默认根据主键加载
	constrained="true",表明当前主键上存在一个约束，person的主键作为外键参照了idcard
 -->
<one-to-one name="idCard" constrained="true" />

 

 

一：实体类：

package com.tao.hibernate.one2one;

public class Person {
	private Integer id;
	private String name;
	private IdCard idCard;

	public Person() {
		super();
	}

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public IdCard getIdCard() {
		return idCard;
	}

	public void setIdCard(IdCard idCard) {
		this.idCard = idCard;
	}

}

 

package com.tao.hibernate.one2one;

public class IdCard {
	private Integer id;
	private String cardNo;
	private Person person;

	public IdCard() {
		super();
	}

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getCardNo() {
		return cardNo;
	}

	public void setCardNo(String cardNo) {
		this.cardNo = cardNo;
	}

	public Person getPerson() {
		return person;
	}

	public void setPerson(Person person) {
		this.person = person;
	}

}

  二：映射文件：

<?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 package="com.tao.hibernate.one2one">
	<class name="Person" table="t_Person">
		<id name="id" column="id" type="integer">
			<!-- Person的主键来源于idCard, 也就是共享idCard主键 -->
			<generator class="foreign">
				<param name="property">idCard</param>
			</generator>
		</id>
		<property name="name" column="name" />
		<!-- one-to-one标签的含义，指示hibernate怎样加载它的关联对象，默认根据主键加载
			constrained="true",表明当前主键上存在一个约束，person的主键作为外键参照了idcard
		 -->
		<one-to-one name="idCard" constrained="true" />
	</class>
</hibernate-mapping>

 

<?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 package="com.tao.hibernate.one2one">
	<class name="IdCard" table="t_IdCard">
		<id name="id" column="id" type="integer">
			<generator class="native" />
		</id>
		<property name="cardNo" column="cardNo" />
		<one-to-one name="person" fetch="select"/>
	</class>
</hibernate-mapping>

 三：测试类

package com.tao.hibernate.one2one;

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;

import com.tao.hibernate.HibernateUtils;

public class TestMain {

	@Test
	public void testSave() {
		Session session = HibernateUtils.getFactory().openSession();

		IdCard idCard = new IdCard();
		idCard.setCardNo("100");

		Person person = new Person();
		person.setName("Tao");
		person.setIdCard(idCard);

		Transaction ts = session.beginTransaction();
		ts.begin();
		session.save(person);
		ts.commit();
	}

	@Test
	public void testLoad() {
		Session session = HibernateUtils.getFactory().openSession();
		Person person = (Person) session.load(Person.class, 2);
		System.out.println(person.getName());
		System.out.println(person.getIdCard().getCardNo());
	}

	@Test
	public void testLoad2() {
		Session session = HibernateUtils.getFactory().openSession();
		IdCard idCard = (IdCard) session.load(IdCard.class, 2);
		System.out.println(idCard.getCardNo());
		System.out.println(idCard.getPerson().getName());
	}

}