hibernate annotation 双向 one-to-one 注解

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Java代码

package com.hibernate.entity;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
@Entity
public class Husband implements Serializable {
/**
*
*/
private static final long serialVersionUID = 2476364405175138004L;
private int id;
private String name;
private Wife wife;
@Id
@GeneratedValue
public int getId() {
return id;
}
public String getName() {
return name;
}
@OneToOne
public Wife getWife() {
return wife;
}
public void setId(int id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public void setWife(Wife wife) {
this.wife = wife;
}
}

Java代码

package com.hibernate.entity;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
@Entity
public class Wife implements Serializable {
/**
*
*/
private static final long serialVersionUID = 5270130768836331730L;
private int id;
private String name;
private Husband husband;
@Id
@GeneratedValue
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;
}
@OneToOne(mappedBy="wife")
public Husband getHusband() {
return husband;
}
public void setHusband(Husband husband) {
this.husband = husband;
}
}

注意：Wife类的getHusband()上用了mappedBy"wife"

这个意思是说，我这里的OneToOne就不用管了，只用Husband里的getWife()上的OneToOne关系

生成的表为Husband参考Wife，有了wifeid，才能有Husband

Husband为这个关系的拥有者

如果Wife类的getHusband()只有@OneToOne，没有mappedBy，那么生成的两张表都会有对方的外键，造成外键冗余。

Test.java

package com.fancy.test;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.AnnotationConfiguration;import org.hibernate.cfg.Configuration;import com.fancy.po.Card;import com.fancy.po.Person;/** * ----------------------------------------- * @文件: Test.java * @作者: fancy * @邮箱: fancyzero@yeah.net * @时间: 2012-6-10 * @描述: 测试类 * ----------------------------------------- */public class Test {    public static void main(String[] args) {                //读取hibernate配置,默认读取classpath下的hibernate.cfg.xml        Configuration conf = new AnnotationConfiguration();            //构建session工厂         SessionFactory sessionFactory = conf.configure().buildSessionFactory();        //打开session        Session session = sessionFactory.openSession();        //开始事务         session.beginTransaction();        // * * * * * * * * * * * * * * * * * * * * * * * * * * * *        //test1(session);    //测试 1        //test2(session);    //测试 2        test3(session);      //测试 3        // * * * * * * * * * * * * * * * * * * * * * * * * * * * *        //提交事务         session.getTransaction().commit();        //关闭session工厂         sessionFactory.close();       //关闭session       session.close();    }    /**     * 数据库初始值：      * personName：fancy     * cardNumber：440911199008011122     */    //测试方法1    public static void test1(Session session){        Person person = (Person)session.get(Person.class, 1); //发出Person和Card的select语句         Card card = person.getCard();        System.out.println(person.getPersonName());        System.out.println(card.getCardNumber());        person.setPersonName("fancy");            //与初始值一致         card.setCardNumber("440911199008011122");//与初始值一致         session.save(person);    //不发出sql语句       //session.save(card);     //不发出sql语句    }    //测试方法2    public static void test2(Session session){        Person person = (Person)session.get(Person.class, 1); //发出Person和Card的select语句         Card card = person.getCard();        System.out.println(person.getPersonName());        System.out.println(card.getCardNumber());        person.setPersonName("fancyzero");        //与初始值不一致         card.setCardNumber("440911199008011122");//与初始值一致         session.save(person);    //发出Person的update语句,数据库中personName被修改,不发出Card的update语句       //session.save(card);     //发出Person的update语句,数据库中personName被修改,不发出Card的update语句    }    //测试方法3    public static void test3(Session session){        Person person = (Person)session.get(Person.class, 1); //发出Person和Card的select语句         Card card = person.getCard();        System.out.println(person.getPersonName());        System.out.println(card.getCardNumber());        person.setPersonName("fancy");           //与初始值不一致         card.setCardNumber("440911199008080808");//与初始值不一致         session.save(person);    //同时发出Person和Card的update语句,数据库中的数据相应被修改       //session.save(card);     //同时发出Person和Card的update语句,数据库中的数据相应被修改    }}