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;+---------------+--------------+------+-----+---------+----------------+| Field???????? | Type???????? | Null | Key | Default | Extra????????? |+---------------+--------------+------+-----+---------+----------------+| addressid???? | int(11)????? | NO?? | PRI | NULL??? | auto_increment || addressdetail | varchar(255) | YES? |???? | NULL??? |??? ????????????|+---------------+--------------+------+-----+---------+----------------+?mysql> desc person_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?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>??? <class name="com.lavasoft.dx._n_1_fk.Personn1fk" table="PERSON_n1fk">??????? <id name="personid">??????????? <generator style="padding-bottom: 0cm; padding-left: 5.4pt; width: 728pt; padding-right: 5.4pt; height: 14.25pt; padding-top: 0cm;">??????? </id>??????? <property name="name"/>??????? <property name="age"/>??????? <!--用来映射关联PO column是Address在该表中的外键列名--> ??????? <many-to-one name="addressn1fk" column="addressId"/>??? </class></hibernate-mapping>?<hibernate-mapping>??? <class name="com.lavasoft.dx._n_1_fk.Addressn1fk" table="ADDRESS_n1fk">??????? <id name="addressid">??????????? <generator style="padding-bottom: 0cm; padding-left: 5.4pt; width: 728pt; padding-right: 5.4pt; height: 14.25pt; padding-top: 0cm;">?????? ?</id>??????? <property name="addressdetail"/>??? </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 (?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 PERSON_n1kf (name, age, addressId) values (?Hibernate: insert into ADDRESS_n1kf (addressdetail) values (?)Hibernate: update PERSON_n1kf set name=Hibernate: update PERSON_n1kf set name=?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 (?Hibernate: insert into PERSON_n1kf (name, age, addressId) values (?Exception in thread "main" org.hibernate.TransientObjectException: com.lavasoft.dx._n_1_fk.Addressn1kf
