数据库：create table student( id int identity(1,1) not null primary key, s_name varchar(50), s_sex varchar(20))gocreate table card( id int primary key, address varchar(100), cardnum varchar(20))
select * from studentselect * from card
delete from carddelete from student
Student.hbm.xml配置如下：（主对象）<hibernate-mapping> <class name="com.mengya.entity.Student" table="student" schema="dbo" catalog="mp"> <id name="id" type="java.lang.Integer"> <column name="id" /> <generator class="native" /> </id> <property name="SName" type="java.lang.String"> <column name="s_name" length="50" /> </property> <property name="SSex" type="java.lang.String"> <column name="s_sex" length="20" /> </property> <!-- 一对一时，没有inverse属性 --> <one-to-one name="card" class="com.mengya.entity.Card" cascade="all"></one-to-one> </class></hibernate-mapping>
Card.hbm.xml配置如下：(从对象)<hibernate-mapping> <class name="com.mengya.entity.Card" table="card" schema="dbo" catalog="mp"> <id name="id" type="java.lang.Integer"> <column name="id" /> <generator class="foreign"> <param name="property">student</param> </generator> </id> <property name="address" type="java.lang.String"> <column name="address" length="100" /> </property> <property name="cardnum" type="java.lang.String"> <column name="cardnum" length="20" /> </property> <one-to-one name="student" class="com.mengya.entity.Student"></one-to-one> </class></hibernate-mapping>
我的测试：public class Test extends MySessionUtil {
private Session session;
private Transaction tran; public void save1(){ Student stu=new Student(); stu.setSName("张明学"); stu.setSSex("男"); Card card=new Card(); card.setAddress("湖北武汉"); card.setCardnum("421125198764212454"); /* * 主方指定从方并且主方 cascade="all"，若从方没有指定主方，会报错 * 也就是说，添加card时没有指定student错误 */ stu.setCard(card); //card.setStudent(stu); session=this.GetSession(); tran=session.beginTransaction(); session.save(stu); tran.commit(); session.close(); } public void save2(){ Student stu=new Student(); stu.setSName("梦娅"); stu.setSSex("女"); Card card=new Card(); card.setAddress("湖北黄冈"); card.setCardnum("421125666546542789"); /* * 从方指定主方，主方不指定从方，可以添加成功 */ card.setStudent(stu); session=this.GetSession(); tran=session.beginTransaction(); session.save(card); tran.commit(); session.close(); } public void select(){ /* * 一对一的查询时，对主方的查询也会自己对从方查询，即不能对从方懒加载 * 因为查询主方时要对从方产生一个代理对象，而这个代理对象在主方中直接得不到，它要去查从方得到代理对象 * 查询从方就可以进行懒加载 */ session=this.GetSession(); Student stu=(Student) session.get(Student.class,new Integer(3)); session.close(); System.out.println(stu.getSName()); System.out.println(stu.getCard().getCardnum()); System.out.println(stu.getCard().getAddress()); } public static void main(String[] args) { Test text=new Test(); //text.save2(); text.select(); }
}
个人说明：在多对一中，若把多方中的一方设置为unique也可以变成一对一的关系。
