映射继承

每个具体类对应一个表

package com.zhiqi.model;

import java.util.Set;

public class Employee {
	private int id;
	private String name;
	private Set<Image> imageSet;

	public Employee() {
		super();
		// TODO Auto-generated constructor stub
	}
	public Employee(String name) {
		super();
		this.name = name;
	}

	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 Set<Image> getImageSet() {
		return imageSet;
	}
	public void setImageSet(Set<Image> imageSet) {
		this.imageSet = imageSet;
	}

}

<?xml version="1.0"?>
<!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.zhiqi.model">
	<class name="Employee" table="t_employee">
		<id name="id" column="employee_id">
			<generator class="native"></generator>
		</id>

		<property name="name" column="emp_name"></property>

	</class>

</hibernate-mapping>

　　Image类设为抽象的

package com.zhiqi.model;

public abstract class Image {
	private int id;
	private String imageName;
	private Employee emp;

	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getImageName() {
		return imageName;
	}
	public void setImageName(String imageName) {
		this.imageName = imageName;
	}
	public Employee getEmp() {
		return emp;
	}
	public void setEmp(Employee emp) {
		this.emp = emp;
	}
}

public class LifeImage extends Image {

}

public class WorkImage extends Image {

}

　　分别配置xml

<?xml version="1.0"?>
<!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.zhiqi.model">
	<class name="WorkImage" table="t_work_image">
		<id name="id" column="work_image_id">
			<generator class="native"></generator>
		</id>

		<property name="imageName" column="image_name"></property>
		<many-to-one name="emp" column="emp_id" class="com.zhiqi.model.Employee"></many-to-one>

	</class>

</hibernate-mapping>

　　设置数据

@Test
	public void testSetDate(){
		Employee emp=new Employee("马化腾");

		LifeImage lifeImage1=new LifeImage();
		lifeImage1.setImageName("li001.jpg");
		LifeImage lifeImage2=new LifeImage();
		lifeImage2.setImageName("li002.jpg");

		WorkImage workImage1=new WorkImage();
		workImage1.setImageName("wi1.jpg");
		WorkImage workImage2=new WorkImage();
		workImage2.setImageName("wi2.jpg");

		lifeImage1.setEmp(emp);lifeImage2.setEmp(emp);
		workImage1.setEmp(emp);workImage2.setEmp(emp);
		session.save(lifeImage1);session.save(lifeImage2);
		session.save(workImage1);session.save(workImage2);
		session.save(emp);
	}

　　获取数据

@Test
	public void testGetDate(){
		Employee emp=(Employee)session.get(Employee.class, Integer.valueOf(1));

		//第一种普通方法

//		Query q1=session.createQuery("from LifeImage l where l.emp.id="+emp.getId());
//		List<LifeImage> list1=q1.list();
//		Query q2=session.createQuery("from WorkImage w where w.emp.id="+emp.getId());
//		List<WorkImage> list2=q2.list();
//		for(LifeImage li:list1){
//			System.out.println(li.getImageName());
//		}
//		for(WorkImage wi:list2){
//			System.out.println(wi.getImageName());
//		}

		//第二种经验方法(集合就迭代器遍历)

		List<Image> imageList=new ArrayList<Image>();

		List<LifeImage> lifeImagelist=session.createQuery("from LifeImage l where l.emp.id="+emp.getId()).list();
		imageList.addAll(lifeImagelist);
		List<WorkImage> WorkImagelist=session.createQuery("from WorkImage w where w.emp.id="+emp.getId()).list();
		imageList.addAll(WorkImagelist);

		Iterator it=imageList.iterator();
		while(it.hasNext()){
			Image image=(Image)it.next();
			System.out.println(image.getImageName());
		}
	}

　　根类对应一个表

<mapping resource="com/zhiqi/model/Employee.hbm.xml"/>
<mapping resource="com/zhiqi/model/Image.hbm.xml"/>

<hibernate-mapping package="com.zhiqi.model">
	<class name="Employee" table="t_employee">
		<id name="id" column="employee_id">
			<generator class="native"></generator>
		</id>

		<property name="name" column="emp_name"></property>

		<set name="imageSet">
			<key column="emp_id"></key>
			<one-to-many class="com.zhiqi.model.Image"></one-to-many>
		</set>
	</class>

</hibernate-mapping>

<hibernate-mapping package="com.zhiqi.model">
	<class name="Image" table="t_image">
		<id name="id" column="image_id">
			<generator class="native"></generator>
		</id>

		<discriminator column="image_type"></discriminator>

		<property name="imageName" column="image_name"></property>

		<many-to-one name="emp" column="emp_id"></many-to-one>
		<subclass name="com.zhiqi.model.LifeImage" discriminator-value="li"></subclass>
		<subclass name="com.zhiqi.model.WorkImage" discriminator-value="wi"></subclass>
	</class>

</hibernate-mapping>

当子类非常多的时候，我们可以选择映射根。