Hibernate 一对一外键单向关联
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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;
+---------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------------+--------------+------+-----+---------+----------------+
| addressid | int(11) | NO | PRI | NULL | auto_increment |
| addressdetail | varchar(255) | YES | | NULL | |
+---------------+--------------+------+-----+---------+----------------+
mysql> desc person_11fk;
+-----------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+----------------+
| personid | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(255) | YES | | NULL | |
| 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;
`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:
<!--用来映射关联PO column是Address在该表中的外键列名,增加unique变成“1-1”-->
<many-to-one name="address11fk" column="addressId" unique="true"/>
<hibernate-mapping>
<classname="com.lavasoft.dx._1_1_fk.Address11fk"table="ADDRESS_11fk">
<idname="addressid">
<generatorclass="identity"/>
</id>
<propertyname="addressdetail"/>
</class>
</hibernate-mapping>
<classname="com.lavasoft.dx._1_1_fk.Address11fk"table="ADDRESS_11fk">
<idname="addressid">
<generatorclass="identity"/>
</id>
<propertyname="addressdetail"/>
</class>
</hibernate-mapping>
<hibernate-mapping>
<classname="com.lavasoft.dx._1_1_fk.Person11fk"table="PERSON_11fk">
<idname="personid">
<generatorclass="identity"/>
</id>
<propertyname="name"/>
<propertyname="age"/>
<!--用来映射关联PO column是Address在该表中的外键列名,增加unique变成“1-1”-->
<many-to-onename="address11fk"column="addressId"unique="true"/>
</class>
</hibernate-mapping>
<classname="com.lavasoft.dx._1_1_fk.Person11fk"table="PERSON_11fk">
<idname="personid">
<generatorclass="identity"/>
</id>
<propertyname="name"/>
<propertyname="age"/>
<!--用来映射关联PO column是Address在该表中的外键列名,增加unique变成“1-1”-->
<many-to-onename="address11fk"column="addressId"unique="true"/>
</class>
</hibernate-mapping>
六、测试方法
public class Test_11fk {
public staticvoid 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();
}
}
public staticvoid 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
转载自:http://lavasoft.blog.51cto.com/62575/39279/
转载自:http://lavasoft.blog.51cto.com/62575/39279/
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