这篇讲解 基于外键的双向一对一关联映射
1.考察如下信息,人和身份证之间是一个一对一的关系。表的设计
2.类结构
Person.java
public class Person implements Serializable{
private int id;
private String name;
private IdCard idCard;
public Person() {
}
public Person(String name) {
super();
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public IdCard getIdCard() {
return idCard;
}
public void setIdCard(IdCard idCard) {
this.idCard = idCard;
}
}
IdCard.java
public class IdCard implements Serializable{
private String id;
private String address;
private Person person;
public IdCard() {
// TODO Auto-generated constructor stub
}
public IdCard(String id, String address) {
super();
this.id = id;
this.address = address;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public Person getPerson() {
return person;
}
public void setPerson(Person person) {
this.person = person;
}
}
3.映射文件
Person.hbm.xml
<hibernate-mapping package="cn.sxt.pojo">
<class name="Person" table="t_person">
<id name="id">
<generator class="native"></generator>
</id>
<property name="name"/>
<!-- 基于外键的一对一和多对一的表结构是一样的,所以映射文件也一样,要保证外键是唯一的 -->
<many-to-one name="idCard" column="idCardId" unique="true"></many-to-one>
</class>
</hibernate-mapping>
IdCard.hbm.xml
<hibernate-mapping package="cn.sxt.pojo">
<class name="IdCard" table="t_idCard">
<id name="id">
<generator class="assigned"></generator>
</id>
<property name="address"/>
<!-- 一对一的双向关联 person表示IdCard类中属性
property-ref引用的是 person类中IdCard的属性名
-->
<one-to-one name="person" property-ref="idCard"></one-to-one>
</class>
</hibernate-mapping>
4.测试
public class HibernateTest {
/**
* 生成数据库表的工具方法
* */
@Test
public void testCreateDB(){
Configuration cfg = new Configuration().configure();
SchemaExport se = new SchemaExport(cfg);
//第一个参数 是否打印sql脚本
//第二个参数 是否将脚本导出到数据库中执行
se.create(true, true);
}
/**
* 初始化表数据
*/
@Test
public void testInit(){
Session session = null;
Transaction tx = null;
try {
session = HibernateUtil.getSession();
tx = session.beginTransaction();
IdCard card1 = new IdCard("110086", "湖北武当");
IdCard card2 = new IdCard("110087", "光明顶");
Person p1 = new Person("张三疯");
p1.setIdCard(card1);
Person p2 = new Person("殷素素");
p2.setIdCard(card2);
session.save(card1);
session.save(card2);
session.save(p1);
session.save(p2);
tx.commit();
} catch (Exception e) {
if(tx!=null)
tx.rollback();
}finally {
HibernateUtil.close();
}
}
/**
*/
@Test
public void testGetData(){
Session session = HibernateUtil.getSession();
Person p1 = (Person)session.get(Person.class, 1);
System.out.println(p1.getName()+"----"+p1.getIdCard().getId()+"----"+p1.getIdCard().getAddress());
System.out.println("-------------------------------------------");
IdCard card = (IdCard)session.get(IdCard.class, "110086");
System.out.println(card.getId()+"------"+card.getAddress()+"----"+card.getPerson().getName());
HibernateUtil.close();
}
}