一对一（双向）

public class Card {
	private int id;
	private int num;
	private Person person;
	
	public int getId() {return id;}
	public void setId(int id) {this.id = id;}
	
	public int getNum() {return num;}
	public void setNum(int num) {this.num = num;}
	
	public Person getPerson() {return person;}
	public void setPerson(Person person) {this.person = person;}
}

public class Person {
	private int id ;
	private String name;
	private Card card;
	
	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 Card getCard() {return card;}
	public void setCard(Card card) {this.card = card;}
}

<?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 package="com.ximen.dao.domain">
    <class name="Card" table="CARD">
        <id name="id" column="ID" type="int">
            <generator class="increment"/>
        </id>
        <property name="num" column="NUM" type="int"/>
        
        <many-to-one name="person" class="Person" unique="true" column="person_id"/>
        
    </class>
</hibernate-mapping>

<?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 package="com.ximen.dao.domain" >
    <class name="Person" table="PERSON">
        <id name="id" column="ID" type="int">
            <generator class="increment" />
        </id>
        <property name="name" column="NAME" type="string"/>
        
        <one-to-one name="card" class="Card" property-ref="person"/>
        
    </class>
</hibernate-mapping>

import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
/**
 * 双向一对一
 */
public class TestOneToOne1 {
	public static void main(String[] args) {
		@SuppressWarnings("deprecation")
		Session session=new Configuration().configure().buildSessionFactory().openSession();
		
		Person person = (Person) session.get(Person.class, 2);
		System.out.println(person.getName()+"的号码是" +person.getCard().getNum());
		Card card = (Card) session.get(Card.class, 2);
		System.out.println(card.getNum()+"是" +card.getPerson().getName()+"的号码");
		session.close();
	}
}