hibernate实例简析-hibernate_one2one_ufk_2

hibernate一对一唯一外键关联映射（双向关联Person<---->IdCard）

一对一唯一外键关联双向，需要在另一端（idcard），添加<one-to-one>标签，指示hibernate如何加载
其关联对象，默认根据主键加载person，外键关联映射中，因为两个实体采用的是person的外键维护的关系，
所以不能指定主键加载person，而要根据person的外键加载，所以采用如下映射方式：
<one-to-one name="person" property-ref="idCard"/>
===
IdCard idCard = new IdCard();
idCard.setCardNo("88888888888888");

Person person = new Person();
person.setName("菜10");
person.setIdCard(idCard);

//不能成功保存，因为IdCard是Transient状态
session.save(person);
---
IdCard idCard = new IdCard();
idCard.setCardNo("88888888888888");
session.save(idCard);

Person person = new Person();
person.setName("菜10");
person.setIdCard(idCard);

session.save(person);
---
Person person = (Person)session.load(Person.class, 2);
System.out.println("person.name=" + person.getName());
System.out.println("idCard.cardNo=" + person.getIdCard().getCardNo());
---
IdCard idCard = (IdCard)session.load(IdCard.class, 1);
System.out.println("idcard.cardNo=" + idCard.getCardNo());
System.out.println("idcard.person.name=" + idCard.getPerson().getName());
===
<hibernate-mapping>
<class name="com.bjsxt.hibernate.Person" table="t_person">
<id name="id">
<generator class="native"/>
</id>
<property name="name"/>
<many-to-one name="idCard" unique="true"/>
</class>
</hibernate-mapping>
---
<hibernate-mapping>
<class name="com.bjsxt.hibernate.IdCard" table="t_idcard">
<id name="id">
<generator class="native"/>
</id>
<property name="cardNo"/>
<one-to-one name="person" property-ref="idCard"/>
</class>
</hibernate-mapping>
===
public class Person {

private int id;

private String name;

private IdCard idCard;
---
public class IdCard {

private int id;

private String cardNo;

private Person person;