（13）Hibernate组件映射

类组合关系的映射，也叫做组件映射！

注意：组件类和被包含的组件类，共同映射到一张表！

需求： 汽车与车轮

生成的表：主键、汽车名称、轮胎大小、轮胎数量

Wheel.java

package com.rk.hibernate.m_component;

public class Wheel
{
	private int count;
	private int size;
	public int getCount()
	{
		return count;
	}
	public void setCount(int count)
	{
		this.count = count;
	}
	public int getSize()
	{
		return size;
	}
	public void setSize(int size)
	{
		this.size = size;
	}

}

Car.java

package com.rk.hibernate.m_component;

public class Car
{
	private int id;
	private String name;
	private Wheel wheel;
	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 Wheel getWheel()
	{
		return wheel;
	}
	public void setWheel(Wheel wheel)
	{
		this.wheel = wheel;
	}

}

Car.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.rk.hibernate.m_component" auto-import="true">
	<class name="Car" table="T_Cars">
		<id name="id" column="carId">
			<generator class="native"></generator>
		</id>
		<property name="name" column="carName"></property>
		<!-- 组件映射 -->
		<component name="wheel">
			<property name="size" column="wheelSize"></property>
			<property name="count" column="wheelCount"></property>
		</component>
	</class>
</hibernate-mapping>

App.java

package com.rk.hibernate.m_component;

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

public class App
{
	private static SessionFactory sf;
	static
	{
		sf = new Configuration()
						.configure()
						.addClass(Car.class)
						.buildSessionFactory();
	}

	@Test
	public void testSave()
	{
		Session session = sf.openSession();
		session.beginTransaction();

		// 轮子
		Wheel wheel = new Wheel();
		wheel.setSize(80);
		wheel.setCount(4);

		// 汽车
		Car car = new Car();
		car.setName("BMW");
		car.setWheel(wheel);

		// 保存
		session.save(car);

		session.getTransaction().commit();
		session.close();
	}

}

生成的数据表