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，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();

}

}

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