Hibernate 一对一外键单向关联

2007-08-22 13:17:58

Hibernate 一对一外键单向关联

事实上，单向1-1与N-1的实质是相同的，1-1是N-1的特例，单向1-1与N-1的映射配置也非常相似。只需要将原来的many-to-one元素增加unique="true"属性，用于表示N的一端也必须是唯一的，在N的一端增加了唯一的约束，即成为单向1-1。基于外键的单向1-1的配置将与无连接表N-1关联的many-to-one增加unique="true"属性即可。

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 Person11fk {

private int personid;

private String name;

private int age;

private Address11fk address11fk;

public class Address11fk {

private int addressid;

private String addressdetail;

三、表模型

mysql> desc address_11fk;

+---------------+--------------+------+-----+---------+----------------+

+---------------+--------------+------+-----+---------+----------------+

| addressid | int(11) | NO | PRI | NULL | auto_increment |

+---------------+--------------+------+-----+---------+----------------+

mysql> desc person_11fk;

+-----------+--------------+------+-----+---------+----------------+

+-----------+--------------+------+-----+---------+----------------+

| personid | int(11) | NO | PRI | NULL | auto_increment |

| age | int(11) | YES | | NULL | |

| addressId | int(11) | YES | UNI | NULL | |

+-----------+--------------+------+-----+---------+----------------+

四、生成的SQL脚本

CREATE TABLE `address_11fk` (

`addressid` int(11) NOT NULL auto_increment,

`addressdetail` varchar(255) default NULL,

PRIMARY KEY (`addressid`)

) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=gbk;

CREATE TABLE `person_11fk` (

`personid` int(11) NOT NULL auto_increment,

`name` varchar(255) default NULL,

`age` int(11) default NULL,

`addressId` int(11) default NULL,

PRIMARY KEY (`personid`),

KEY `FK68A8818F3F45AA77` (`addressId`),

CONSTRAINT `FK68A8818F3F45AA77` FOREIGN KEY (`addressId`) REFERENCES `address_11fk` (`addressid`)

) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=gbk;

五、映射方法：

在Person中添加Address属性，映射配置为：

<many-to-one name="address11fk" column="addressId" unique="true"/>

<hibernate-mapping>

</id>

</class>

</hibernate-mapping>

<hibernate-mapping>

</id>

<many-to-one name="address11fk" column="addressId" unique="true"/>

</class>

</hibernate-mapping>

六、测试方法

public class Test_11fk {

public static void main(String[] args){

Person11fk p1=new Person11fk();

p1.setAge(21);

p1.setName("p1");

Address11fk add1=new Address11fk();

add1.setAddressdetail("郑州市经三路");

p1.setAddress11fk(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

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Hibernate 一对一外键单向关联

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