需求：学生有很多照片，分为生活照和工作照；
第一节：每个具体类对应一个表
Student.java:
package com.cy.model;
import java.util.Set;
public class Student {
private int id;
private String name;
private Set<Image> images;
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> getImages() {
return images;
}
public void setImages(Set<Image> images) {
this.images = images;
}
}
抽象类Image.java:
package com.cy.model;
public abstract class Image {
private int id;
private String imageName;
private Student student;
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 Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}
}
生活照LifeImage.java:
package com.cy.model;
public class LifeImage extends Image{
}
工作照WorkImage.java:
package com.cy.model;
public class WorkImage extends Image{
}
Student.hbm.xml:
<hibernate-mapping package="com.cy.model">
<class name="Student" table="t_student">
<id name="id" column="stuId">
<generator class="native"></generator>
</id>
<property name="name" column="stuName"></property>
</class>
</hibernate-mapping>
LifeImage.hbm.xml:
<hibernate-mapping package="com.cy.model">
<class name="LifeImage" table="t_lifeImage">
<id name="id" column="lifeImageId">
<generator class="native"></generator>
</id>
<property name="imageName" column="imageName"></property>
<many-to-one name="student" column="stuId" class="com.cy.model.Student"></many-to-one>
</class>
</hibernate-mapping>
WorkImage.hbm.xml:
<hibernate-mapping package="com.cy.model">
<class name="WorkImage" table="t_workImage">
<id name="id" column="workImageId">
<generator class="native"></generator>
</id>
<property name="imageName" column="imageName"></property>
<many-to-one name="student" column="stuId" class="com.cy.model.Student"></many-to-one>
</class>
</hibernate-mapping>
测试代码StudentTest.java:
@Test
public void testGetAllImages(){
List<Image> imageList = new ArrayList<Image>();
int stuId = 1;
List<Image> lifeImageList = (List<Image>)session.createQuery("from LifeImage l where l.student.id = " + stuId).list();
imageList.addAll(lifeImageList);
List<Image> workImageList = (List<Image>)session.createQuery("from WorkImage w where w.student.id = " + stuId).list();
imageList.addAll(workImageList);
for(Image image: imageList){
System.out.println(image.getImageName());
}
}
三个表的关联关系：
t_lifeimage表结构：
t_lifeimage表数据：
t_workimage表数据：
第二节：根类对应一个表
Student2.java:
package com.cy.model;
import java.util.Set;
public class Student2 {
private int id;
private String name;
private Set<Image2> images;
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<Image2> getImages() {
return images;
}
public void setImages(Set<Image2> images) {
this.images = images;
}
}
Image2.java:
package com.cy.model;
public class Image2 {
private int id;
private String imageType;
private String imageName;
private Student2 student;
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 Student2 getStudent() {
return student;
}
public void setStudent(Student2 student) {
this.student = student;
}
public String getImageType() {
return imageType;
}
public void setImageType(String imageType) {
this.imageType = imageType;
}
}
LifeImage2.java:
package com.cy.model;
public class LifeImage2 extends Image2{
}
WorkImage2.java:
package com.cy.model;
public class WorkImage2 extends Image2{
}
Student2.hbm.xml:
<hibernate-mapping package="com.cy.model">
<class name="Student2" table="t_student2">
<id name="id" column="stuId">
<generator class="native"></generator>
</id>
<property name="name" column="stuName"></property>
<set name="images">
<key column="stuId"></key>
<one-to-many class="com.cy.model.Image2"/>
</set>
</class>
</hibernate-mapping>
Image2.hbm.xml:
<hibernate-mapping package="com.cy.model">
<class name="Image2" table="t_image2">
<id name="id" column="imageId">
<generator class="native"></generator>
</id>
<!-- 用来区分是LifeImage2还是WorkImage2 -->
<discriminator column="imageType" type="string"></discriminator>
<property name="imageName" column="imageName"></property>
<many-to-one name="student" column="stuId" class="com.cy.model.Student2"></many-to-one>
<subclass name="com.cy.model.LifeImage2" discriminator-value="life"></subclass>
<subclass name="com.cy.model.WorkImage2" discriminator-value="work"></subclass>
</class>
</hibernate-mapping>
hibernate.cfg.xml中只需加入两项映射配置就行了：
<mapping resource="com/cy/model/Student2.hbm.xml"/> <mapping resource="com/cy/model/Image2.hbm.xml"/>
测试代码：
@Test
public void testGetAllImages2(){
Student2 s2 = (Student2) session.get(Student2.class, 1);
Set<Image2> images = s2.getImages();
Iterator<Image2> it = images.iterator();
while(it.hasNext()){
Image2 image = it.next();
System.out.println(image.getImageName());
}
}
生成的t_image2表结构：
第三节：每个类对应一个表
Student3.java:
package com.cy.model;
import java.util.Set;
public class Student3 {
private int id;
private String name;
private Set<Image3> images;
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<Image3> getImages() {
return images;
}
public void setImages(Set<Image3> images) {
this.images = images;
}
}
Image3.java:
package com.cy.model;
public class Image3 {
private int id;
private String imageName;
private Student3 student;
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 Student3 getStudent() {
return student;
}
public void setStudent(Student3 student) {
this.student = student;
}
}
WorkImage3.java:
package com.cy.model;
public class WorkImage3 extends Image3{
}
LifeImage3.java:
package com.cy.model;
public class LifeImage3 extends Image3{
}
Student3.hbm.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.cy.model">
<class name="Student3" table="t_student3">
<id name="id" column="stuId">
<generator class="native"></generator>
</id>
<property name="name" column="stuName"></property>
<set name="images">
<key column="stuId"></key>
<one-to-many class="com.cy.model.Image3"/>
</set>
</class>
</hibernate-mapping>
Image3.hbm.xml:
<hibernate-mapping package="com.cy.model">
<class name="Image3" table="t_image3">
<id name="id" column="imageId">
<generator class="native"></generator>
</id>
<property name="imageName" column="imageName"></property>
<many-to-one name="student" column="stuId" class="com.cy.model.Student3"></many-to-one>
<joined-subclass name="com.cy.model.LifeImage3" table="t_lifeImage3">
<key column="lifeImageId"></key>
</joined-subclass>
<joined-subclass name="com.cy.model.WorkImage3" table="t_workImage3">
<key column="workImageId"></key>
</joined-subclass>
</class>
</hibernate-mapping>
hibernate.cfg.xml中加入如下映射关系：
<mapping resource="com/cy/model/Student3.hbm.xml"/> <mapping resource="com/cy/model/Image3.hbm.xml"/>
测试代码：
@Test
public void testGetAllImages3(){
Student3 s3 = (Student3) session.get(Student3.class, 1);
Set<Image3> images = s3.getImages();
Iterator<Image3> it = images.iterator();
while(it.hasNext()){
Image3 image = it.next();
System.out.println(image.getImageName());
}
}
查看生成的表：
t_image3的表结构：