hibernate继承映射

继承关系

                   一个类继承另外一个类。这2个类中就是继承关系。

                   需求：动物

　　　　　　　　猫

　　　　　　　　猴子

---

案例一

package loaderman.e_extends1;

// 动物类
public abstract class Animal {

    private int id;
    private String 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;
    }
    
}

package loaderman.e_extends1;

import java.util.List;

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

public class App {

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

    @Test
    public void getSave() {

        Session session = sf.openSession();
        session.beginTransaction();

        // 保存
//        Cat cat = new Cat();
//        cat.setName("大花猫");
//        cat.setCatchMouse("抓小老鼠");
//        session.save(cat);

        // 获取时候注意：当写hql查询的使用，通过父类查询必须写上类的全名
        Query q = session.createQuery("from loaderman.e_extends1.Animal");
        List<Animal> list = q.list();
        System.out.println(list);

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

    }

}

package loaderman.e_extends1;

public class Cat extends Animal{


    // 抓老鼠
    private String catchMouse;

    public String getCatchMouse() {
        return catchMouse;
    }

    public void setCatchMouse(String catchMouse) {
        this.catchMouse = catchMouse;
    }

    
    
}

package loaderman.e_extends1;

public class Monkey {

    // 吃香蕉
    private String eatBanana;
    
    
}

<?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">

<!-- 
    简单继承
 -->
<hibernate-mapping package="loaderman.e_extends1">
    
    <class name="Cat" table="t_Cat">
        <!-- 简单继承映射： 父类属性直接写 -->
        <id name="id">
            <generator class="native"></generator>
        </id>
        <property name="name"></property>
        
        
        <property name="catchMouse"></property>                     
    </class>
    

</hibernate-mapping>

---

案例二

package loaderman.e_extends2;


public abstract class Animal {

    private int id;
    private String 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;
    }
    
}

package loaderman.e_extends2;

import java.util.List;

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

public class App {

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

    @Test
    public void getSave() {

        Session session = sf.openSession();
        session.beginTransaction();

        // 保存
        Cat cat = new Cat();
        cat.setName("大花猫");
        cat.setCatchMouse("抓小老鼠");

        Monkey m = new Monkey();
        m.setName("猴子");
        m.setEatBanana("吃10个香蕉");

        // 保存
        session.save(cat);
        session.save(m);

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

    }

}

package loaderman.e_extends2;

public class Cat extends Animal{


    private String catchMouse;

    public String getCatchMouse() {
        return catchMouse;
    }

    public void setCatchMouse(String catchMouse) {
        this.catchMouse = catchMouse;
    }

    
    
}

package loaderman.e_extends2;

public class Monkey extends Animal {
    

    private String eatBanana;

    public String getEatBanana() {
        return eatBanana;
    }

    public void setEatBanana(String eatBanana) {
        this.eatBanana = eatBanana;
    }
    
}

<?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">

<!-- 
    继承映射， 所有的子类都映射到一张表
 -->
<hibernate-mapping package="loaderman.e_extends2">
    
    <class name="Animal" table="t_animal">
        <id name="id">
            <generator class="native"></generator>
        </id>
        <!-- 指定鉴别器字段(区分不同的子类) -->
        <discriminator column="type_"></discriminator>
        
        <property name="name"></property>
        
        <!-- 
            子类：猫
                每个子类都用subclass节点映射
                注意：一定要指定鉴别器字段，否则报错！
                鉴别器字段：作用是在数据库中区别每一个子类的信息， 就是一个列
            discriminator-value="cat_"
                指定鉴别器字段,即type_字段的值
                如果不指定，默认为当前子类的全名
         -->
         <subclass name="Cat" discriminator-value="cat_">
             <property name="catchMouse"></property>
         </subclass>
         
         <!-- 
             子类：猴子
          -->
          <subclass name="Monkey" discriminator-value="monkey_">
              <property name="eatBanana"></property>
          </subclass>
        
    </class>
    

</hibernate-mapping>

---

案例三

package loaderman.e_extends3;


public abstract class Animal {

    private int id;
    private String 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;
    }
    
}

package loaderman.e_extends3;

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

public class App {

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

    @Test
    public void getSave() {

        Session session = sf.openSession();
        session.beginTransaction();

        // 保存
        Cat cat = new Cat();
        cat.setName("大花猫");
        cat.setCatchMouse("抓小老鼠");

        Monkey m = new Monkey();
        m.setName("猴子");
        m.setEatBanana("吃10个香蕉");

        // 保存
        session.save(cat);
        session.save(m);

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

    }

}

package loaderman.e_extends3;

public class Cat extends Animal{


    private String catchMouse;

    public String getCatchMouse() {
        return catchMouse;
    }

    public void setCatchMouse(String catchMouse) {
        this.catchMouse = catchMouse;
    }

    
    
}

package loaderman.e_extends3;

public class Monkey extends Animal {
    

    private String eatBanana;

    public String getEatBanana() {
        return eatBanana;
    }

    public void setEatBanana(String eatBanana) {
        this.eatBanana = eatBanana;
    }
    
    
    
    
}

<?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">

<!-- 
    继承映射， 每个类对应一张表(父类也对应表)
 -->
<hibernate-mapping package="loaderman.e_extends3">
    
    <class name="Animal" table="t_animal">
        <id name="id">
            <generator class="native"></generator>
        </id>
        <property name="name"></property>
        
        <!-- 
            子类：猫  t_cat
            key 指定_cat表的外键字段
        -->
        <joined-subclass name="Cat" table="t_cat">
            <key column="t_animal_id"></key>
            <property name="catchMouse"></property>
        </joined-subclass>
        
        <!-- 子类：猴子  t_monkey -->
        <joined-subclass name="Monkey" table="t_monkey">
            <key column="t_animal_id"></key>
            <property name="eatBanana"></property>
        </joined-subclass>
        
    </class>
    

</hibernate-mapping>

---

案例四

package loaderman.e_extends4;


public class Animal {

    private String id;
    private String name;
    
    
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    
}

package loaderman.e_extends4;


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

public class App {

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

    @Test
    public void getSave() {

        Session session = sf.openSession();
        session.beginTransaction();

        // 保存
        Cat cat = new Cat();
        cat.setName("大花猫");
        cat.setCatchMouse("抓小老鼠");

        Monkey m = new Monkey();
        m.setName("猴子");
        m.setEatBanana("吃10个香蕉");

        // 保存
        session.save(cat);
        session.save(m);

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

    }

}

package loaderman.e_extends4;

public class Cat extends Animal{

    private String catchMouse;

    public String getCatchMouse() {
        return catchMouse;
    }

    public void setCatchMouse(String catchMouse) {
        this.catchMouse = catchMouse;
    }

    
    
}

package loaderman.e_extends4;

public class Monkey extends Animal {

    private String eatBanana;

    public String getEatBanana() {
        return eatBanana;
    }

    public void setEatBanana(String eatBanana) {
        this.eatBanana = eatBanana;
    }
    
}

<?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">

<!-- 
    继承映射， 每个类对应一张表(父类不对应表)
 -->
<hibernate-mapping package="loaderman.e_extends4">
    <!-- 
         abstract="true"  指定实体类对象不对应表，即在数据库段不生成表
     -->
    <class name="Animal" abstract="true">
        <!-- 如果用union-subclass节点，主键生成策略不能为自增长！ -->
        <id name="id">
            <generator class="uuid"></generator>
        </id>
        <property name="name"></property>
        
        <!-- 
            子类：猫  t_cat
            union-subclass  
                table 指定为表名, 表的主键即为id列
        -->
        <union-subclass name="Cat" table="t_cat">
            <property name="catchMouse"></property>
        </union-subclass>
        
        <!-- 子类：猴子  t_monkey -->
        <union-subclass name="Monkey" table="t_monkey">
            <property name="eatBanana"></property>
        </union-subclass>
        
    </class>
    

</hibernate-mapping>