Hibernate之one-to-one主键关联映射

one-to-one映射的例子为一个人拥有一个身份证，一个身份证属于一个人。

先创建po类

Person.java

package po;

public class Person {
private int id;
private String name;  //姓名
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;
}

}

Card.java

package po;

public class Card {
private int id;          //身份证ID
private String number;   //身份证号码
private Person person;   //一个身份证号对应一个人

public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
public Person getPerson() {
return person;
}
public void setPerson(Person person) {
this.person = person;
}

}

po类的映射文件

Person.hbm.xml

<hibernate-mapping>
<class name="po.Person" table="person">
<id name="id" type="integer">
<generator class="native" />
</id>
<property name="name" />
</class>

</hibernate-mapping>

Card.hbm.xml

<hibernate-mapping>
<class name="po.Card" table="card">
<id name="id" type="integer">
<!-- 主键生成方式为foreign -->
<generator class="foreign">
<param name="property">person</param>
</generator>
</id>
<property name="number"></property>
<!-- !!!constrained=true表示生成外键约束 -->
<one-to-one name="person" constrained="true"></one-to-one>
</class>
</hibernate-mapping>

hibernate.cfg.xml

<hibernate-configuration>

<session-factory>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>
<property name="connection.username">root</property>
<property name="connection.password">1</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="myeclipse.connection.profile">mysql</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<mapping resource="po/Person.hbm.xml"/>
<mapping resource="po/Card.hbm.xml"/>
</session-factory>
</hibernate-configuration

测试类Test.java

package po;

import java.util.Date;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

public class Test {

@Test
public void testCreateDB(){
//生成表结构
Configuration config = new Configuration().configure();
SchemaExport export = new SchemaExport(config);
export.create(true, true);
}
@Test
public void testSave(){
//测试 添加数据
Configuration config = new Configuration().configure();
SessionFactory factory = config.buildSessionFactory();
Session session = factory.openSession();
session.beginTransaction();

Person person = new Person();   //先有person然后才能有省份证
person.setName("zhangsan");

Card card = new Card();
card.setNumber("4114031111222223333");
card.setPerson(person);       //此身份证属于此人
session.save(card);           //保存card

session.getTransaction().commit();

}
@Test
public void testGetPerson(){
Configuration config = new Configuration().configure();
SessionFactory factory = config.buildSessionFactory();
Session session = factory.openSession();
session.beginTransaction();

Card card = (Card)session.get(Card.class,1 ); //取出Card
System.out.println("CardNumber: "+card.getNumber());

Person person = card.getPerson();  //通过card.getPerson()方法 返回person
System.out.println("PersonName: "+person.getName()); //取出person的name

session.getTransaction().commit();
session.close();
}
}

hibernate后天生成表结构sql为

create table card (
id integer not null,
number varchar(255),
primary key (id)
)

create table person (
id integer not null auto_increment,
name varchar(255),
primary key (id)
)
alter table card
add index FK2E7B10F83A3F5F (id),
add constraint FK2E7B10F83A3F5F
foreign key (id)
references person (id)