Hibernate 多对一外键单向关联
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一、模型介绍
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多个人（Person）对应一个地址（Address）。
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二、实体（省略getter、setter方法）
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public class Personn1fk {
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private int personid;
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private String name;
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private int age;
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private Addressn1fk addressn1fk;
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public class Addressn1fk {
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private int addressid;
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private String addressdetail;
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三、表模型
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mysql> desc address_n1kf;
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+---------------+--------------+------+-----+---------+----------------+
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| Field | Type | Null | Key | Default | Extra |
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+---------------+--------------+------+-----+---------+----------------+
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| addressid | int(11) | NO | PRI | NULL | auto_increment |
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| addressdetail | varchar(255) | YES | | NULL | |
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+---------------+--------------+------+-----+---------+----------------+
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mysql> desc person_n1kf;
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+-----------+--------------+------+-----+---------+----------------+
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| Field | Type | Null | Key | Default | Extra |
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+-----------+--------------+------+-----+---------+----------------+
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| personid | int(11) | NO | PRI | NULL | auto_increment |
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| name | varchar(255) | YES | | NULL | |
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| age | int(11) | YES | | NULL | |
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| addressId | int(11) | YES | MUL | NULL | |
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+-----------+--------------+------+-----+---------+----------------+
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四、生成的SQL脚本
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CREATE TABLE `address_n1kf` (
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`addressid` int(11) NOT NULL auto_increment,
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`addressdetail` varchar(255) default NULL,
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PRIMARY KEY (`addressid`)
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) ENGINE=InnoDB DEFAULT CHARSET=gbk;
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DROP TABLE IF EXISTS `person_n1kf`;
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CREATE TABLE `person_n1kf` (
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`personid` int(11) NOT NULL auto_increment,
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`name` varchar(255) default NULL,
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`age` int(11) default NULL,
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`addressId` int(11) default NULL,
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PRIMARY KEY (`personid`),
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KEY `FK4571AF54A2A3EE48` (`addressId`),
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CONSTRAINT `FK4571AF54A2A3EE48` FOREIGN KEY (`addressId`) REFERENCES `address_n1kf` (`addressid`)
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) ENGINE=InnoDB DEFAULT CHARSET=gbk;
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五、映射方法
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<hibernate-mapping>
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<class name="com.lavasoft.dx._n_1_fk.Personn1fk" table="PERSON_n1fk">
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<id name="personid">
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<generator class="identity"/>
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</id>
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<property name="name"/>
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<property name="age"/>
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<!--
用来映射关联PO column是Address在该表中的外键列名-->
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<many-to-one name="addressn1fk" column="addressId"/>
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</class>
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</hibernate-mapping>
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<hibernate-mapping>
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<class name="com.lavasoft.dx._n_1_fk.Addressn1fk" table="ADDRESS_n1fk">
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<id name="addressid">
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<generator class="identity"/>
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</id>
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<property name="addressdetail"/>
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</class>
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</hibernate-mapping>
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六、测试方法
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public class Test_n1fk {
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public static void main(String[] args){
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Personn1fk p1=new Personn1fk();
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Personn1fk p2=new Personn1fk();
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p1.setAge(21);
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p1.setName("p1");
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p2.setAge(23);
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p2.setName("p2");
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Addressn1fk add=new Addressn1fk();
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add.setAddressdetail("
郑州市经三路");
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p1.setAddressn1fk(add);
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p2.setAddressn1fk(add);
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Session session=HibernateUtil.getCurrentSession();
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Transaction tx=session.beginTransaction();
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session.save(add);
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session.save(p1);
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session.save(p2);
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tx.commit();
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HibernateUtil.closeSession();
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}
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}
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七、测试结果
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1) :
正常保存. 推荐这么干!
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session.save(p1);
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session.save(p2);
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Hibernate: insert into ADDRESS_n1kf (addressdetail) values (?)
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Hibernate: insert into PERSON_n1kf (name, age, addressId) values (?, ?, ?)
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Hibernate: insert into PERSON_n1kf (name, age, addressId) values (?, ?, ?)
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2) :
正常保存.
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session.save(p1);
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session.save(p2);
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session.save(add);
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Hibernate: insert into PERSON_n1kf (name, age, addressId) values (?, ?, ?)
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Hibernate: insert into PERSON_n1kf (name, age, addressId) values (?, ?, ?)
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Hibernate: insert into ADDRESS_n1kf (addressdetail) values (?)
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Hibernate: update PERSON_n1kf set name=?, age=?, addressId=? where personid=?
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Hibernate: update PERSON_n1kf set name=?, age=?, addressId=? where personid=?
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3) :
正常保存.
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session.save(add);
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// session.save(p1);
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// session.save(p2);
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Hibernate: insert into ADDRESS_n1kf (addressdetail) values (?)
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4) :
发生异常,不能保存.
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// session.save(add);
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session.save(p1);
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session.save(p2);
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Hibernate: insert into PERSON_n1kf (name, age, addressId) values (?, ?, ?)
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Hibernate: insert into PERSON_n1kf (name, age, addressId) values (?, ?, ?)
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Exception in thread "main" org.hibernate.TransientObjectException: com.lavasoft.dx._n_1_fk.Addressn1kf
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