15. component映射

componenet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通常被称为是值对象（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

1.定义Contact类

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;

       }

}

2.定义User类

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;

       }    

}

3.定义User.hbm.xml文件

<?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>

4.定义hibernate.cfg.xml文件

<!DOCTYPE hibernate-configuration PUBLIC

       "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

       "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

 

<hibernate-configuration>

       <session-factory>

<property name="hibernate.connection.url">jdbc:mysql://localhost/hibernate_component_mapping</property>

              <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>

              <property name="hibernate.connection.username">root</property>

              <property name="hibernate.connection.password">bjsxt</property>

              <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>

              <property name="hibernate.show_sql">true</property>

             

              <mapping resource="com/bjsxt/hibernate/User.hbm.xml"/>

       </session-factory>

</hibernate-configuration>

5.定义ExportDB.java和HibernateUtils.java（略）

6.编写测试用例

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("xxx@rrr.com");

                     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);

              }

       }           

}

表结构：

t_user表包含id,name,email,address,zipcode,contacttel六个字段