Hibernate 一對一外鍵單向關聯

2019-11-10 17:59:32

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Hibernate 一對一外鍵單向關聯 事實上，單向1-1與N-1的實質是相同的，1-1是N-1的特例，單向1-1與N-1的映射配置也非常相似。只需要將原來的many-to-one元素增加unique="true"屬性，用于表示N的一端也必須是唯一的，在N的一端增加了唯一的約束，即成為單向1-1。基于外鍵的單向1-1的配置將與無連接表N-1關聯的many-to-one增加unique="true"屬性即可。 一、模型介紹 一個人（Person）對應一個地址（Address）。 二、實體（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腳本 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; 五、映射方法： 在Person中添加Address屬性，映射配置為：  <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> <hibernate-mapping> <classname="com.lavasoft.dx._1_1_fk.Person11fk"table="PERSON_11fk"> <idname="personid"> <generatorclass="identity"/> </id> <propertyname="name"/> <propertyname="age"/>  <many-to-onename="address11fk"column="addressId"unique="true"/> </class></hibernate-mapping> 六、測試方法 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("鄭州市經三路"); p1.setAddress11fk(add1); session session= HibernateUtil.getCurrentSession(); Transaction tx=session.beginTransaction(); session.save(add1); session.save(p1); tx.commit(); HibernateUtil.closeSession(); } } 七、測試結果 1) :正常保存. 推薦這么干! 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) : 發生異常,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

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