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Hibernate 一对一主键单向关联

2009-12-04 13:23 483 查看
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Hibernate 一对一主键单向关联
1-1的关联可以基于主键关联，但基于主键关联的持久化类不能拥有自己的主键生成策略，它的主键由关联类负责生成。另外，
增加one-to-one元素来关联属性，必须为one-to-one元素增加constrained="true"属性，表明该类主键由关联类生成。
一、模型介绍
一个人（Person）对应一个地址（Address）。
二、实体（省略getter、setter方法）
public class Person11pk {
private int personid;
private String name;
private int age;
private Address11pk address11pk;

public class Address11pk {
private int addressid;
private String addressdetail;


三、表模型
mysql> desc address_11pk;
+---------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------------+--------------+------+-----+---------+----------------+
| addressid | int(11) | NO | PRI | NULL | auto_increment |
| addressdetail | varchar(255) | YES | | NULL | |
+---------------+--------------+------+-----+---------+----------------+
mysql> desc person_11pk;
+----------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+--------------+------+-----+---------+-------+
| personid | int(11) | NO | PRI | | |
| name | varchar(255) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
+----------+--------------+------+-----+---------+-------+

四、生成的SQL脚本
/* Formatted on 2007/08/22 14:40 (QP5 v5.50) */
CREATE TABLE `address_11pk` (
`addressid` int(11) NOT NULL auto_increment,
`addressdetail` varchar(255) default NULL,
PRIMARY KEY (`addressid`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=gbk;
/* Formatted on 2007/08/22 14:41 (QP5 v5.50) */
CREATE TABLE `person_11pk` (
`presonid` int(11) NOT NULL,
`name` varchar(255) default NULL,
`age` int(11) default NULL,
PRIMARY KEY (`presonid`),
KEY `FK68A882C591BB393E` (`presonid`),
CONSTRAINT `FK68A882C591BB393E` FOREIGN KEY (`presonid`) REFERENCES `address_11pk` (`addressid`)
) ENGINE=InnoDB DEFAULT CHARSET=gbk;

五、映射方法：在Person中配置id生成策略为：

<id name="personid">
<!--基于主键关联时，主键生成策略是foreign，表明根据关联类生成主键-->
<generator class="foreign">
<!--关联持久化类的属性名-->
<param name="property">address11pk</param>
</generator>
</id>
......
<!--用于映射1-1关联-->
<one-to-one name="address11pk" constrained="true"/>

<hibernate-mapping>
<class name="com.lavasoft.dx._1_1_pk.Person11pk" table="PERSON_11pk">
<id name="personid" column="presonid">
<!--基于主键关联时，主键生成策略是foreign，表明根据关联类生成主键-->
<generator class="foreign">
<!--关联持久化类的属性名-->
<param name="property">address11pk</param>
</generator>
</id>
<property name="name"/>
<property name="age"/>
<!--用于映射1-1关联-->
<one-to-one name="address11pk" constrained="true"/>
</class>
</hibernate-mapping>

<hibernate-mapping>
<class name="com.lavasoft.dx._1_1_pk.Address11pk" table="ADDRESS_11pk">
<id name="addressid">
<generator class="identity"/>
</id>
<property name="addressdetail"/>
</class>
</hibernate-mapping>


六、测试方法
public class Test_11pk {
public static void main(String[] args){
Person11pk p1=new Person11pk();

p1.setAge(21);
p1.setName("p1");

Address11pk add1=new Address11pk();
add1.setAddressdetail("郑州市经三路");

p1.setAddress11pk(add1);

Session session= HibernateUtil.getCurrentSession();
Transaction tx=session.beginTransaction();
session.save(add1);
session.save(p1);
tx.commit();
HibernateUtil.closeSession();
}
}



[b]七、测试结果
1) :正常保存. 推荐这么干!
session.save(add1);
session.save(p1);

Hibernate: insert into ADDRESS_11fk (addressdetail) values (?)
Hibernate: insert into PERSON_11fk (name, age, addressId) values (?, ?, ?)

2) :正常保存.
session.save(p1);
session.save(add1);

Hibernate: insert into PERSON_11fk (name, age, addressId) values (?, ?, ?)
Hibernate: insert into ADDRESS_11fk (addressdetail) values (?)
Hibernate: update PERSON_11fk set name=?, age=?, addressId=? where personid=?

3) :正常保存.
//        session.save(p1);
session.save(add1);

Hibernate: insert into ADDRESS_11fk (addressdetail) values (?)

4) : 发生异常,不能保存.
session.save(p1);
//        session.save(add1);

Hibernate: insert into PERSON_11fk (name, age, addressId) values (?, ?, ?)
Exception in thread "main" org.hibernate.TransientObjectException: com.lavasoft.dx._1_1_fk.Address11fk



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