三种继承映射关系。

 

1，SINGLE_TABLE

 

person student  teacher 在一个表中，student和teacher继承自person，通过一个DiscriminatorValue的内容来标识该条内容是student还是teacher。

 

package com.bjsxt.hibernate;

import javax.persistence.DiscriminatorColumn;

import javax.persistence.DiscriminatorType;

import javax.persistence.DiscriminatorValue;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.Inheritance;

import javax.persistence.InheritanceType;

@Entity

@Inheritance(strategy=InheritanceType.SINGLE_TABLE)

@DiscriminatorColumn(name="discriminator", discriminatorType=DiscriminatorType.STRING)

@DiscriminatorValue("person")

public class Person {

    private int id;

    private String name;

   

    @Id

    @GeneratedValue

    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 com.bjsxt.hibernate;

import javax.persistence.DiscriminatorValue;

import javax.persistence.Entity;

@Entity

@DiscriminatorValue("student")

public class Student extends Person {

   

    private int score;

    public int getScore() {

        return score;

    }

    public void setScore(int score) {

        this.score = score;

    }

   

}

 

package com.bjsxt.hibernate;

import javax.persistence.DiscriminatorValue;

import javax.persistence.Entity;

@Entity

@DiscriminatorValue("teacher")

public class Teacher extends Person {

    private String title;

    public String getTitle() {

        return title;

    }

    public void setTitle(String title) {

        this.title = title;

    }

   

}

 

 

 

测试类：

package com.bjsxt.hibernate;

import java.util.Map;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.AnnotationConfiguration;

import org.hibernate.tool.hbm2ddl.SchemaExport;

import org.junit.AfterClass;

import org.junit.BeforeClass;

import org.junit.Test;

public class HibernateORMappingTest {

    private static SessionFactory sessionFactory;

   

    @BeforeClass

    public static void beforeClass() {

        new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);

        sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();

    }

    @AfterClass

    public static void afterClass() {

        sessionFactory.close();

    }

   

    @Test

    public void testSave() {

        Student s = new Student();

        s.setName("s1");

        s.setScore(80);

        Teacher t = new Teacher();

        t.setName("t1");

        t.setTitle("中级");

       

        Session session = sessionFactory.openSession();

        session.beginTransaction();

        session.save(s);

        session.save(t);

        session.getTransaction().commit();

        session.close();

    }

    @Test

    public void testLoad() {

       

        testSave();

        Session session = sessionFactory.openSession();

        session.beginTransaction();

        Student s = (Student)session.load(Student.class, 1);

        System.out.println(s.getScore());

        Person p = (Person)session.load(Person.class, 2);

        System.out.println(p.getName());

        session.getTransaction().commit();

        session.close();

       

    }

   

    @Test

    public void testSchemaExport() {

        new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);

    }

   

   

    public static void main(String[] args) {

        beforeClass();

    }

}