Hibernate4自学入门（九）——映射继承

一、每个具体类对应一个表

model

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;}}

一个抽象的父类

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;}}

多个继承上述抽象父类的子类：

public class LifeImage extends Image {}

每个实体类对应一个表 即：student、workImage、LifeImage各生成一张表

<hibernate-mapping package="com.gw.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.gw.model.Student"></many-to-one></class></hibernate-mapping>

LifeImage同上、Student即标准写法。

test:

@Testpublic void test() throws IOException, ParseException {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);Iterator it=imageList.iterator();while(it.hasNext()){Image image =(Image)it.next();System.out.println(image.getImageName());}}

二、根类对应一个表

student 不变。

根类Image:

public  class Image2 {private int id;private String imageName;private Student2 student;private String imageType;public String getImageType() {return imageType;}public void setImageType(String imageType) {this.imageType = imageType;}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;}}

概念：imageType 用来给表里的信息进行分类提取——对应下述的discriminator。

根类对应的表：

<hibernate-mapping package="com.gw.model"><class name="Image2" table="t_image2"><id name="id" column="imageId"><generator class="native"></generator></id><discriminator column="imageType" type="string"></discriminator><property name="imageName" column="imageName"></property><many-to-one name="student" column="stuId" class="com.gw.model.Student2"></many-to-one><subclass name="com.gw.model.LifeImage2" discriminator-value="li"></subclass><subclass name="com.gw.model.WorkImage2" discriminator-value="wo"></subclass></class></hibernate-mapping>

Student对应的表

<hibernate-mapping package="com.gw.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.gw.model.Image2"/> </set></class></hibernate-mapping>

test:

@Testpublic void test2() throws IOException, ParseException {Student2  student2 = (Student2) session.get(Student2.class, 1);Set<Image2> images=student2.getImages();Iterator it=images.iterator();while(it.hasNext()){Image2 image =(Image2)it.next();System.out.println(image.getImageName());}} 

三、每个类对应一个表

image根类和Student model类不变 两个子类不变

Student对应的表：

<hibernate-mapping package="com.gw.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.gw.model.Image3"/> </set></class></hibernate-mapping>

Image对应的表：

<hibernate-mapping package="com.gw.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.gw.model.Student3"></many-to-one><joined-subclass name="com.gw.model.LifeImage3" table="t_lifeImage3"><key column="lifeImageId"></key></joined-subclass><joined-subclass name="com.gw.model.WorkImage3" table="t_workImage3"><key column="workImageId"></key></joined-subclass></class></hibernate-mapping>