单向一对一主键关联实例

IdCard.java类

public class IdCard {

	private int id;
	
	private String cardNo;

	public int getId() {
		return id;
	}

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

	public String getCardNo() {
		return cardNo;
	}

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

Person.java类

public class Person {

	private int id;
	
	private String name;
	
	private IdCard idCard;

	public int getId() {
		return id;
	}

	public void setId(int 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;
	}

}

IdCard.hbm.xml映射文件

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.hibernate.IdCard" table="t_idCard">
		<id name="id">
			<generator class="native">
			</generator>
		</id>
		<property name="cardNo"/>
	</class>
</hibernate-mapping>

Person.hbm.xml映射文件

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.hibernate.Person" table="t_person">
		<id name="id">
			<!-- 采用foreign生成策略，foreign会取得关联对象的标识 -->
			<generator class="foreign">
				<!-- property只关联对象 -->
				<param name="property">idCard</param>
			</generator>
		</id>
		<property name="name"/>
		<!-- one-to-one指示hibernate如何加载其关联对象，默认根据主键加载
			也就是拿到关系字段值，根据对端的主键来加载关联对象
		 -->
		<one-to-one name="idCard" constrained="true"/>
	</class>
</hibernate-mapping>

hibernate.cfg.xml配置文件

<!DOCTYPE hibernate-configuration PUBLIC
	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
	<session-factory>
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernate_one2one_pk_1</property>
		<property name="hibernate.connection.username">root</property>
		<property name="hibernate.connection.password">root</property>
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		<property name="hibernate.show_sql">true</property>
		
		<mapping resource="com/hibernate/Person.hbm.xml"/>
		<mapping resource="com/hibernate/IdCard.hbm.xml"/>
	</session-factory>
</hibernate-configuration>

One2OneTest.java测试类（里面用到的工具类前面的博客中已经给出）

       public void testSave1(){
		Session session = null;
		try{
			session = HibernateUtils.getSession();
			session.beginTransaction();
			
			IdCard idCard = new IdCard();
			idCard.setCardNo("1111111111111111111");
			
			Person person = new Person();
			person.setName("张三");
			//建立关联
			person.setIdCard(idCard);
			
			//没有抛出TransientObjectException
			//是由一对一关联映射的特性决定的，它必须先保存关联对象IdCard
			//这样它采用foreign映射策略才能取得关联对象的标识
			//也就是它默认了cascade属性
			session.save(person);
			
			session.getTransaction().commit();
		}catch(Exception e){
			e.printStackTrace();
			session.getTransaction().rollback();
		}finally{
			HibernateUtils.closeSession(session);
		}
	}

测试结果（发出的sql语句）：

Hibernate: insert into t_idCard (cardNo) values (?)
Hibernate: insert into t_person (name, id) values (?, ?)