Hibernate 多对一外键单向关联

2019-11-10 18:08:11

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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）

public class Personn1fk {

PRivate int personid;

private String name;

private int age;

private Addressn1fk addressn1fk;

public class Addressn1fk {

private int addressid;

private String addressdetail;

三、表模型

MySQL> desc address_n1kf;

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

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

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

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

mysql> desc person_n1kf;

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

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

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

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

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

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

四、生成的SQL脚本

CREATE TABLE `address_n1kf` (

`addressid` int(11) NOT NULL auto_increment,

`addressdetail` varchar(255) default NULL,

PRIMARY KEY (`addressid`)

) ENGINE=InnoDB DEFAULT CHARSET=gbk;

DROP TABLE IF EXISTS `person_n1kf`;

CREATE TABLE `person_n1kf` (

`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 `FK4571AF54A2A3EE48` (`addressId`),

CONSTRAINT `FK4571AF54A2A3EE48` FOREIGN KEY (`addressId`) REFERENCES `address_n1kf` (`addressid`)

) ENGINE=InnoDB DEFAULT CHARSET=gbk;

五、映射方法

<hibernate-mapping>

</id>

<many-to-one name="addressn1fk" column="addressId"/>

</class>

</hibernate-mapping>

<hibernate-mapping>

</id>

</class>

</hibernate-mapping>

六、测试方法

public class Test_n1fk {

public static void main(String[] args){

Personn1fk p1=new Personn1fk();

Personn1fk p2=new Personn1fk();

p1.setAge(21);

p1.setName("p1");

p2.setAge(23);

p2.setName("p2");

Addressn1fk add=new Addressn1fk();

add.setAddressdetail("郑州市经三路");

p1.setAddressn1fk(add);

p2.setAddressn1fk(add);

session session=HibernateUtil.getCurrentSession();

Transaction tx=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: insert into ADDRESS_n1kf (addressdetail) values (?)

Hibernate: insert into PERSON_n1kf (name, age, addressId) values (?, ?, ?)

2) :正常保存.

session.save(p1);

session.save(p2);

session.save(add);

Hibernate: insert into PERSON_n1kf (name, age, addressId) values (?, ?, ?)

Hibernate: insert into ADDRESS_n1kf (addressdetail) values (?)

Hibernate: update PERSON_n1kf set name=?, age=?, addressId=? where personid=?

3) :正常保存.

session.save(add);

// session.save(p1);

// session.save(p2);

Hibernate: insert into ADDRESS_n1kf (addressdetail) values (?)

4) : 发生异常,不能保存.

// session.save(add);

session.save(p1);

session.save(p2);

Hibernate: insert into PERSON_n1kf (name, age, addressId) values (?, ?, ?)

Exception in thread "main" org.hibernate.TransientObjectException: com.lavasoft.dx._n_1_fk.Addressn1kf

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