Hibernate基于配置文件（十四）组合映射Component

组合关系
--体现整体与部分同存同亡
--数据存储到一张表中，提交检索速度
--数据都在一张表中，不存在延迟加载的问题，使用load或get都一样

--一个类持有多个component，字段需取别名以示区分

 

package org.leadfar.hibernate.model;

public class Person {

	private int id;
	private String name;
	private Address work;
	private Address home;
	
	
	Person() {
	}



	public Address getWork() {
		return work;
	}



	public void setWork(Address work) {
		this.work = work;
	}



	public Address getHome() {
		return home;
	}



	public void setHome(Address home) {
		this.home = home;
	}



	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;
	}

}

 

package org.leadfar.hibernate.model;

public class Address {
	private String province;
	private String city;
	private String street;
	
	Address(){}
	
	public String getProvince() {
		return province;
	}
	public void setProvince(String province) {
		this.province = province;
	}
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	public String getStreet() {
		return street;
	}
	public void setStreet(String street) {
		this.street = street;
	}
	
	
	
}

 

<?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 
	package="org.hibernate.auction">
	<!-- name为实体类 table为映射到数据库中的表  lazy默认为true 延迟发出select语句，直到真正用到对象的属性(非id属性)-->
	<class name="org.leadfar.hibernate.model.Person" table="t_person" >
		<!-- id为数据库标识，作为主键 -->
		<id name="id">
			<generator class="native"/>
		</id>
		
		<property name="name"/>
		
		<component name="work" class="org.leadfar.hibernate.model.Address">
			<property name="province" column="work_p"/>
			<property name="city" column="work_c"/>
			<property name="street" column="work_s"/>
		</component>
		
		<component name="home" class="org.leadfar.hibernate.model.Address">
			<property name="province" column="home_p"/>
			<property name="city" column="home_c"/>
			<property name="street" column="home_s"/>
		</component>
		
	</class>
	
</hibernate-mapping>

 

测试

package org.leadfar.hibernate.model;




import junit.framework.TestCase;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class Test_Component_01 extends TestCase {

	
	public void testSave_01() throws Exception {
		//默认读取类路径根目录下的hibernate.cfg.xml配置文件
		Configuration cfg = new Configuration().configure();
		
		//创建SessionFactory
		//buildSessionFactory的时候会自动创建数据库表
		SessionFactory sfactory = cfg.buildSessionFactory();
		
		//创建Hibernate Session
		Session session = sfactory.openSession();
		
		try {
			//开启事务
			session.beginTransaction();
			
			Person p = new Person();
			p.setName("张三");
			
			Address home = new Address();
			home.setProvince("四川");
			home.setCity("眉山");
			home.setStreet("洪雅");
			
			Address work = new Address();
			work.setProvince("北京");
			work.setCity("北京");
			work.setStreet("马家堡");
			
			p.setHome(home);
			p.setWork(work);
			
			session.save(p);
			
			//提交事务
			session.getTransaction().commit();
			
		} catch(Exception e) {
			e.printStackTrace();
			//出现异常，回滚事务
			session.getTransaction().rollback();
		} finally {
			//关闭session
			session.close();//session关闭之后，user对象处于离线Detached状态
		}
	}
	public void testLoad_01() throws Exception {
		//默认读取类路径根目录下的hibernate.cfg.xml配置文件
		Configuration cfg = new Configuration().configure();
		
		//创建SessionFactory
		//buildSessionFactory的时候会自动创建数据库表
		SessionFactory sfactory = cfg.buildSessionFactory();
		
		//创建Hibernate Session
		Session session = sfactory.openSession();
		
		try {
			//开启事务
			session.beginTransaction();
			
			Person p = (Person)session.load(Person.class, 2);
			System.out.println(p.getId()+","+p.getName()+","+p.getWork().getProvince()+","+p.getHome().getProvince());
			
			//提交事务
			session.getTransaction().commit();
			
		} catch(Exception e) {
			e.printStackTrace();
			//出现异常，回滚事务
			session.getTransaction().rollback();
		} finally {
			//关闭session
			session.close();//session关闭之后，user对象处于离线Detached状态
		}
	}
	
	
	
}