Hibernate 多对一外键单向关联
Hibernate多对一外键单向关联
一、模型介绍
多个人（Person）对应一个地址（Address）。
二、实体（省略getter、setter方法）
publicclassPersonn1fk{
privateintpersonid;
privateStringname;
privateintage;
privateAddressn1fkaddressn1fk;
publicclassAddressn1fk{
privateintaddressid;
privateStringaddressdetail;
三、表模型
mysql>descaddress_n1kf;
+---------------+--------------+------+-----+---------+----------------+
|Field|Type|Null|Key|Default|Extra|
+---------------+--------------+------+-----+---------+----------------+
|addressid|int(11)|NO|PRI|NULL|auto_increment|
|addressdetail|varchar(255)|YES||NULL||
+---------------+--------------+------+-----+---------+----------------+
mysql>descperson_n1kf;
+-----------+--------------+------+-----+---------+----------------+
|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|MUL|NULL||
+-----------+--------------+------+-----+---------+----------------+
四、生成的SQL脚本
CREATETABLE`address_n1kf`(
`addressid`int(11)NOTNULLauto_increment,
`addressdetail`varchar(255)defaultNULL,
PRIMARYKEY(`addressid`)
)ENGINE=InnoDBDEFAULTCHARSET=gbk;
DROPTABLEIFEXISTS`person_n1kf`;
CREATETABLE`person_n1kf`(
`personid`int(11)NOTNULLauto_increment,
`name`varchar(255)defaultNULL,
`age`int(11)defaultNULL,
`addressId`int(11)defaultNULL,
PRIMARYKEY(`personid`),
KEY`FK4571AF54A2A3EE48`(`addressId`),
CONSTRAINT`FK4571AF54A2A3EE48`FOREIGNKEY(`addressId`)REFERENCES`address_n1kf`(`addressid`)
)ENGINE=InnoDBDEFAULTCHARSET=gbk;
五、映射方法
<hibernate-mapping>
<classname="com.lavasoft.dx._n_1_fk.Personn1fk"table="PERSON_n1fk">
<idname="personid">
<generatorclass="identity"/>
</id>
<propertyname="name"/>
<propertyname="age"/>
<!--用来映射关联POcolumn是Address在该表中的外键列名-->
<many-to-onename="addressn1fk"column="addressId"/>
</class>
</hibernate-mapping>
<hibernate-mapping>
<classname="com.lavasoft.dx._n_1_fk.Addressn1fk"table="ADDRESS_n1fk">
<idname="addressid">
<generatorclass="identity"/>
</id>
<propertyname="addressdetail"/>
</class>
</hibernate-mapping>
六、测试方法
publicclassTest_n1fk{
publicstaticvoidmain(String[]args){
Personn1fkp1=newPersonn1fk();
Personn1fkp2=newPersonn1fk();
p1.setAge(21);
p1.setName("p1");
p2.setAge(23);
p2.setName("p2");
Addressn1fkadd=newAddressn1fk();
add.setAddressdetail("郑州市经三路");
p1.setAddressn1fk(add);
p2.setAddressn1fk(add);
Sessionsession=HibernateUtil.getCurrentSession();
Transactiontx=session.beginTransaction();
session.save(add);
session.save(p1);
session.save(p2);
tx.commit();
HibernateUtil.closeSession();
}
}
七、测试结果
1):正常保存.推荐这么干!
session.save(p1);
session.save(p2);
Hibernate:insertintoADDRESS_n1kf(addressdetail)values(?)
Hibernate:insertintoPERSON_n1kf(name,age,addressId)values(?,?,?)
Hibernate:insertintoPERSON_n1kf(name,age,addressId)values(?,?,?)
2):正常保存.
session.save(p1);
session.save(p2);
session.save(add);
Hibernate:insertintoPERSON_n1kf(name,age,addressId)values(?,?,?)
Hibernate:insertintoPERSON_n1kf(name,age,addressId)values(?,?,?)
Hibernate:insertintoADDRESS_n1kf(addressdetail)values(?)
Hibernate:updatePERSON_n1kfsetname=?,age=?,addressId=?wherepersonid=?
Hibernate:updatePERSON_n1kfsetname=?,age=?,addressId=?wherepersonid=?
3):正常保存.
session.save(add);
//session.save(p1);
//session.save(p2);
Hibernate:insertintoADDRESS_n1kf(addressdetail)values(?)
4):发生异常,不能保存.
//session.save(add);
session.save(p1);
session.save(p2);
Hibernate:insertintoPERSON_n1kf(name,age,addressId)values(?,?,?)
Hibernate:insertintoPERSON_n1kf(name,age,addressId)values(?,?,?)
Exceptioninthread"main"org.hibernate.TransientObjectException:com.lavasoft.dx._n_1_fk.Addressn1kf
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