事实上,单向1-1与N-1的实质是相同的,1-1是N-1的特例,单向1-1与N-1的映射配置也非常相似。只需要将原来的many-to-one元素增加unique="true"属性,用于表示N的一端也必须是唯一的,在N的一端增加了唯一的约束,即成为单向1-1。基于外键的单向1-1的配置将与无连接表N-1关联的many-to-one增加unique="true"属性即可。
一、模型介绍 一个人(Person)对应一个地址(Address)。 二、实体(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脚本 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属性,映射配置为: <!-- 用来映射关联PO column是Address在该表中的外键列名,增加unique变成“1-1”--> <many-to-one name="address11fk" column="addressId" unique="true"/> < hibernate-mapping > < class name ="com.lavasoft.dx._1_1_fk.Address11fk" table ="ADDRESS_11fk" > < id name ="addressid" > < generator class ="identity" /> </ id > < property name ="addressdetail" /> </ class > </ hibernate-mapping > < hibernate-mapping > < class name ="com.lavasoft.dx._1_1_fk.Person11fk" table ="PERSON_11fk" > < id name ="personid" > < generator class ="identity" /> </ 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,增加unique变成“1-1”--> < many-to-one name ="address11fk" column ="addressId" unique ="true" /> </ class > </ hibernate-mapping > 六、测试方法 public class Test_11fk { public static void main(String[] args){ Person11fk p1= new Person11fk(); p1.setAge(21); p1.setName( "p1"); Address11fk add1= new Address11fk(); add1.setAddressdetail( "郑州市经三路"); p1.setAddress11fk(add1); Session session= HibernateUtil.getCurrentSession(); Transaction tx=session.beginTransaction(); session.save(add1); session.save(p1); tx.commit(); HibernateUtil.closeSession(); } } 七、测试结果 1) : 正常保存. 推荐这么干! 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) : 发生异常,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