hibernate_component_mapping

component映射

在hibernate中,component是某个实体的逻辑组成部分，它与实体的根本区别是没有oid，
component可以成为是值对象（DDD）

采用component映射的好处：它实现了对象模型的细粒度划分，层次会更分明，复用率会更高

User.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.User" table="t_user">
        <id name="id">
            <generator class="native"/>
        </id>
        <property name="name"/>
        <component name="contact">
            <property name="email"/>
            <property name="address"/>
            <property name="zipCode"/>
            <property name="contactTel"/>
        </component>
    </class>
</hibernate-mapping>

 
User.java

package com.bjsxt.hibernate;

public class User {
    
    private int id;
    
    private String name;
    
    private Contact contact; 
    
    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 Contact getContact() {
        return contact;
    }

    public void setContact(Contact contact) {
        this.contact = contact;
    }
    
}

Contact.java
package com.bjsxt.hibernate;

public class Contact {
    
    private String email;
    
    private String address;
    
    private String zipCode;
    
    private String contactTel;

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getZipCode() {
        return zipCode;
    }

    public void setZipCode(String zipCode) {
        this.zipCode = zipCode;
    }

    public String getContactTel() {
        return contactTel;
    }

    public void setContactTel(String contactTel) {
        this.contactTel = contactTel;
    }
}

 
ComponentMappingTest.java

package com.bjsxt.hibernate;

import org.hibernate.Session;

import junit.framework.TestCase;

public class ComponentMappingTest extends TestCase {

    public void testSave1() {
        Session session = null;
        try {
            session = HibernateUtils.getSession();
            session.beginTransaction();
            
            User user = new User();
            user.setName("张三");
            
            Contact contact = new Contact();
            contact.setAddress("xxxxx");
            contact.setEmail("[e-mail]");
            contact.setZipCode("1111111");
            contact.setContactTel("9999999999");
            
            user.setContact(contact);
            
            session.save(user);
            session.getTransaction().commit();
        }catch(Exception e) {
            e.printStackTrace();
            session.getTransaction().rollback();
        }finally {
            HibernateUtils.closeSession(session);
        }
    }        
}