学步园

本教程每节课都附带源码，强烈大家建议配合源码学习。
本节源码：http://download.csdn.net/detail/e421083458/5253726

组件映射

对象关系：一个对象是另外一个对象的一部分

实现方式两种：

Annotaion方式：

对象模型
　　Husband(id,name,wife)
　　Wife(name,age)
　　Annotation:
　　在Husband的wife属性上建立注解
　　@Embedded 表明该对象是从别的位置嵌入过来的,是不需要单独映射的表.
　　这种方式生成的表为husband(id,name,wifename,wifeage),不会生成wife表.
　　
@AttributeOverride注解需要写在getWife方法上,可以重新指定生成的Wife类组件生成的字段名,例如:Husband与Wife两个类中都有name字段,这样在生成表的时候会有冲突,此时采用@AttributeOverride注解可以指定Wife类中的name属性对应新的字段名—“wifename”,不过@AttributeOverride注解不常用,因为有更好的解决方法.
    1：不要在组件的两个映射类中写同名属性；2：如果真的有重复，那么可以在分类中（此处为Wife类）的重复名称的属性上使用如下内容以指定新的字段名：
　　　　@Column(name="wifename")
    public String getName() {
        return name;
　　    }
　　
　　另外，@ Embeddable注解好像是写在分类（Wife类）的类名前的，不过好像不写也行
　　@Embeddable
　　public class Wife {… …}

XML方式：

<class name="Husband" >
    <id name="id">
        <generator class="native"/>        
    </id>
    <property name="name"></property>
    <component name="wife">
    <property name="wifename"/>            
    　　　　<property name="wifeAge"/>
    </component>
</class>

项目源码：

Husband.java

package com.bjsxt.hibernate;

import javax.persistence.Embedded;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinColumns;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
@Entity
public class Husband {
    private int id;
    private String name;
    private Wife wife;
    @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;
    }
    @Embedded
    public Wife getWife() {
        return wife;
    }
    public void setWife(Wife wife) {
        this.wife = wife;
    }
}

Wife.java

package com.bjsxt.hibernate;


public class Wife {
    private String wifename;
    private int age;
    public String getWifename() {
        return wifename;
    }
    public void setWifename(String wifename) {
        this.wifename = wifename;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    
}

Husband.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="com.bjsxt.hibernate.Husband" >
        <id name="id">
            <generator class="native"></generator>
        </id>
        
        <property name="name"></property>
        <component name="wife">
            <property name="wifename"></property>
            <property name="age"></property>
        </component>
    </class>
    
</hibernate-mapping>

测试脚本：

package com.bjsxt.hiberante;


import java.util.Date;

import org.hibernate.Query;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.hibernate.Session;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import com.bjsxt.hibernate.Husband;
import com.bjsxt.hibernate.Wife;


public class HibernateQLTest {
    private static SessionFactory sf;

    @BeforeClass
    public static void setUpBeforeClass() throws Exception {
        System.out.println("BeforeClass");
        sf = new AnnotationConfiguration().configure().buildSessionFactory();
    }

    @AfterClass
    public static void tearDownAfterClass() throws Exception {
        System.out.println("AfterClass");
        sf.close();
    }
    //
    @Test
    public void testSchemaExport(){
        new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);        
    }
    @Test
    public void testOneTOOne_Wife(){
        Session session = sf.getCurrentSession();
        session.beginTransaction();
        Wife wife = new Wife();
        wife.setWifename("wife");
        wife.setAge(24);
        Husband husband = new Husband();
        husband.setName("husband");
        husband.setWife(wife);
        session.save(husband);                        //再保存丈夫
        session.getTransaction().commit();
    }
    public static void main(String args[]){
        sf = new AnnotationConfiguration().configure().buildSessionFactory();
        
        Session session = sf.getCurrentSession();
        session.beginTransaction();
        Wife wife = new Wife();
        wife.setWifename("wife");
        wife.setAge(24);
        Husband husband = new Husband();
        husband.setName("husband");
        husband.setWife(wife);
        session.save(husband);                        //再保存丈夫
        session.getTransaction().commit();
        
        sf.close();        
    }
}