Hibernate 一对一连接表单向关联

这种情况很少见，但Hibernate同样允许采用连接表关联1-1.有连接表的1-1同样只需要将N-1的many-to-one元素增加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 Person11tab {

private int personid;

private String name;

private int age;

private Address11tab address11tab;

public class Address11tab {

private int addressid;

private String addressdetail;

三、表模型

mysql> desc address_11tab;

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

| Field         | Type         | Null | Key | Default | Extra          |

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

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

| addressdetail | varchar(255) | YES  |     | NULL    |                |

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

mysql> desc join_11tab;

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

| Field        | Type    | Null | Key | Default | Extra |

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

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

| address11tab | int(11) | YES  | UNI | NULL    |       |

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

mysql> desc person_11tab;

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

| Field    | Type         | Null | Key | Default | Extra          |

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

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

| name     | varchar(255) | YES  |     | NULL    |                |

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

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

四、生成的SQL脚本

/* Formatted on 2007/08/20 16:52 (QP5 v5.50) */

CREATE TABLE `join_11tab` (

`personid` int(11) NOT NULL,

`address11tab` int(11) default NULL,

PRIMARY KEY  (`personid`),

UNIQUE KEY `address11tab` (`address11tab`),

KEY `FK6B44BE20C4CC3D33` (`address11tab`),

KEY `FK6B44BE209049BB1F` (`personid`),

CONSTRAINT `FK6B44BE209049BB1F` FOREIGN KEY (`personid`) REFERENCES `person_11tab` (`personid`),

CONSTRAINT `FK6B44BE20C4CC3D33` FOREIGN KEY (`address11tab`) REFERENCES `address_11tab` (`addressid`)

) ENGINE=InnoDB DEFAULT CHARSET=gbk;

/* Formatted on 2007/08/20 16:53 (QP5 v5.50) */

CREATE TABLE `address_11tab` (

`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 2007/08/20 16:53 (QP5 v5.50) */

CREATE TABLE `person_11tab` (

`personid` int(11) NOT NULL auto_increment,

`name` varchar(255) default NULL,

`age` int(11) default NULL,

PRIMARY KEY  (`personid`)

) 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：

<!-- 使用join元素显式确定链接表-->

<join table="join_11tab">

<key column="personid"/>

<!-- 映射1-1关联属性，其中unique=“true”属性确定为“1-1”-->

<many-to-one name="address11tab" unique="true"/>

</join>

<hibernate-mapping>

<class name="com.lavasoft.dx._1_1_tab.Person11tab" table="PERSON_11tab">

<id name="personid">

<generator class="identity"/>

</id>

<property name="name"/>

<property name="age"/>

<!-- 使用join元素显式确定链接表-->

<join table="join_11tab">

<key column="personid"/>

<!-- 映射1-1关联属性，其中unique=“true”属性确定为“1-1”-->

<many-to-one name="address11tab" unique="true"/>

</join>

</class>

</hibernate-mapping>

<hibernate-mapping>

<class name="com.lavasoft.dx._1_1_tab.Address11tab" table="ADDRESS_11tab">

<id name="addressid">

<generator class="identity"/>

</id>

<property name="addressdetail"/>

</class>

</hibernate-mapping>

六、测试方法

public class Test_11tab {

public static void main(String[] args){

Person11tab p1=new Person11tab();

p1.setAge(21);

p1.setName("p1");

Address11tab add1=new Address11tab();

add1.setAddressdetail(" 郑州市经三路");

p1.setAddress11tab(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_11tab (addressdetail) values (?)

Hibernate: insert into PERSON_11tab (name, age) values (?, ?)

Hibernate: insert into join_11tab (address11tab, personid) values (?, ?)

2) : 正常保存.

session.save(p1);

session.save(add1);

Hibernate: insert into PERSON_11tab (name, age) values (?, ?)

Hibernate: insert into join_11tab (address11tab, personid) values (?, ?)

Hibernate: insert into ADDRESS_11tab (addressdetail) values (?)

Hibernate: update join_11tab set address11tab=? where personid=?

3) : 正常保存.

//        session.save(p1);

session.save(add1);

Hibernate: insert into ADDRESS_11tab (addressdetail) values (?)

4) : 发生异常,不能保存.

session.save(p1);

//        session.save(add1);

Hibernate: insert into PERSON_11tab (name, age) values (?, ?)

Hibernate: insert into join_11tab (address11tab, personid) values (?, ?)

Exception in thread "main" org.hibernate.TransientObjectException: com.lavasoft.dx._1_1_tab.Address11t