Hibernate学习总结：OneToOne单向主键关联

说明：

一、还是举那个一夫一妻的例子来讲述一对一单向主键关联。

二、本次使用的Hibernate版本是hibernate-release-4.3.11.Final.

先写Annotation版本：

实体类：

1.Husband.java

package com.buaa.hibernate.bean;import javax.persistence.Entity;import javax.persistence.Id;import javax.persistence.MapsId;import javax.persistence.OneToOne;@Entitypublic class Husband {private int id;private String name;private Wife wife;@Idpublic 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@MapsId //4.3.11版本的Hibernate将注解PrimaryKeyJoinColumn→MapsIdpublic Wife getWife() {return wife;}public void setWife(Wife wife) {this.wife = wife;}}

Wife.java：

package com.buaa.hibernate.bean;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;@Entitypublic class Wife {private int id;private String name;@Id@GeneratedValuepublic 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;}}

xml版本：

Husband.hbm.xml：

<?xml version="1.0" encoding="utf-8"?><!DOCTYPE hibernate-mapping PUBLIC  "-//Hibernate/Hibernate Mapping DTD//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><hibernate-mapping package="com.buaa.hibernate.bean"><class name="Husband" table="HUSBAND">    <id name="id" column="wifeId">        <generator class="foreign">            <param name="property">wife</param>        </generator>    </id>    <property name="name"/>    <one-to-one name="wife" constrained="true"/></class><class name="Wife"><id name="id"><generator class="native" /></id><property name="name"/></class></hibernate-mapping>

此处将两个类写在一个配置文件里面了，并且配置文件里面的<one-to-one/>元素属性constrained一定要设置为true,如果不设置的话，将不会产生外键关联。

配置文件hibernate.cfg.xml:

<?xml version="1.0" encoding="utf-8"?><!DOCTYPE hibernate-configuration SYSTEM "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"><hibernate-configuration>   <session-factory>      <property name="connection.driver_class">com.mysql.jdbc.Driver</property>   <!-- Assume test is the database name -->   <property name="connection.url">jdbc:mysql://localhost/test</property>   <property name="connection.username">root</property>   <property name="connection.password">123456</property>      <property name="dialect">org.hibernate.dialect.MySQLDialect</property>   <property name="show_sql">true</property>      <property name="format_sql">true</property>   <!--<property name="hbm2ddl.auto">create</property>--><!--<mapping resource="com/buaa/hibernate/bean/Husband.hbm.xml"/>--><mapping class="com.buaa.hibernate.bean.Husband"/><mapping class="com.buaa.hibernate.bean.Wife"/></session-factory></hibernate-configuration>

下面是Junit测试类：

package com.buaa.hibernate.bean;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.boot.registry.StandardServiceRegistryBuilder;import org.hibernate.cfg.Configuration;import org.hibernate.service.ServiceRegistry;import org.hibernate.tool.hbm2ddl.SchemaExport;import org.junit.Test;public class OneToOneTest {@Testpublic void test(){Wife wife = new Wife();wife.setName("lisa");Husband t = new Husband();t.setName("james");t.setWife(wife);Configuration cfg = new Configuration().configure();ServiceRegistry service = new StandardServiceRegistryBuilder().applySettings(cfg.getProperties()).build();SessionFactory factory = cfg.buildSessionFactory(service);Session session = factory.openSession();session.beginTransaction();session.save(wife);session.save(t);session.getTransaction().commit();session.close();factory.close();}@Testpublic void SchemaExportTest(){Configuration cfg = new Configuration().configure();//第一个参数是否将sql语句输出到控制台，第二个参数是否在数据库中生成对应的表格new SchemaExport(cfg).create(true, true);}}