Hibernate逍遥游记-第10章 映射继承关系-002继承关系树中的根类对应一个表(discriminator、subclass)

1.

2.

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping >

   <class name="mypack.Monkey" table="MONKEYS">
      <id name="id" type="long" column="ID">
        <generator class="increment"/>
      </id>
      <discriminator column="MONKEY_TYPE" type="string"  />  
      <property name="name" type="string" column="NAME" />

      <many-to-one
        name="team"
        column="TEAM_ID"
        class="mypack.Team"
      />

      <subclass name="mypack.JMonkey" discriminator-value="JM" >
         <property name="color" column="COLOR" type="string" />
      </subclass>

      <subclass name="mypack.CMonkey" discriminator-value="CM" >
         <property name="length" column="LENGTH" type="double" />
      </subclass>
     
    </class>
 
</hibernate-mapping>

3.

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping >

  <class name="mypack.Team" table="TEAMS" >
    <id name="id" type="long" column="ID">
      <generator class="increment"/>
    </id>

    <property name="name" type="string"  column="NAME" />
    <set 
        name="monkeys"
        inverse="true"
     >
        <key column="TEAM_ID" />
        <one-to-many class="mypack.Monkey" />
     </set>   

  </class>
</hibernate-mapping>

4.

package mypack;

abstract public class Monkey{

    private Long id;
    private String name;
    private Team team;

    /** full constructor */
    public Monkey(String name,Team team) {
        this.name = name;
        this.team = team;
    }

    /** default constructor */
    public Monkey() {
    }

    public Long getId() {
        return this.id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Team getTeam() {
        return this.team;
    }

    public void setTeam(Team team) {
        this.team = team;
    }
}

5.

package mypack;

public class CMonkey extends Monkey {

    private double length;

    /** full constructor */
    public CMonkey(String name, double length,Team team) {
        super(name,team);
        this.length=length;
        
    }

    /** default constructor */
    public CMonkey() {
    }

   public double getLength() {
        return this.length;
    }

    public void setLength(double length) {
        this.length = length;
    }
}

6.

package mypack;


public class JMonkey extends Monkey{

    private String color;

    /** full constructor */
    public JMonkey(String name, String color,Team team) {
        super(name,team);
        this.color=color;
    }

    /** default constructor */
    public JMonkey() {
    }

    public String getColor() {
        return this.color;
    }

    public void setColor(String color) {
        this.color = color;
    }
    
}

7.

package mypack;

import java.util.Set;
import java.util.HashSet;

public class Team {

    private Long id;
    private String name;
    private Set monkeys=new HashSet();

    /** full constructor */
    public Team(String name, Set monkeys) {
        this.name = name;
        this.monkeys = monkeys;
    }

    /** default constructor */
    public Team() {
    }

    /** minimal constructor */
    public Team(Set monkeys) {
        this.monkeys = monkeys;
    }

    public Long getId() {
        return this.id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Set getMonkeys() {
        return this.monkeys;
    }

    public void setMonkeys(Set monkeys) {
        this.monkeys = monkeys;
    }
}

8.

package mypack;

import org.hibernate.*;
import org.hibernate.cfg.Configuration;
import java.util.*;
import java.sql.*;

public class BusinessService{
  public static SessionFactory sessionFactory;
  static{
     try{
       Configuration config = new Configuration().configure();
       sessionFactory = config.buildSessionFactory();
     }catch(RuntimeException e){e.printStackTrace();throw e;}

  }

  public void saveMonkey(Monkey monkey) {
      Session session = sessionFactory.openSession();
      Transaction tx = null;
      List results=new ArrayList();
      try {
       tx = session.beginTransaction();
       session.save(monkey);
       tx.commit();
    }catch (RuntimeException e) {
      if (tx != null) {
        tx.rollback();
      }
      throw e;
    } finally {
      session.close();
    }
  }


  public List findAllJMonkeys(){
      Session session = sessionFactory.openSession();
      Transaction tx = null;

      try {

       tx = session.beginTransaction();
       List results=session.createQuery("from JMonkey").list();
       tx.commit();
       return results;
    }catch (RuntimeException e) {
      if (tx != null) {
        tx.rollback();
      }
      throw e;
    } finally {
      session.close();
    }
  }

  public List findAllMonkeys(){
      Session session = sessionFactory.openSession();
      Transaction tx = null;

      try {
       tx = session.beginTransaction();
       List results=session.createQuery("from Monkey").list();
       tx.commit();
       return results;
     }catch (RuntimeException e) {
      if (tx != null) {
        tx.rollback();
      }
      throw e;
    } finally {
      session.close();
    }
  }

  public Team loadTeam(long id){
      Session session = sessionFactory.openSession();
      Transaction tx = null;
      try {
       tx = session.beginTransaction();
       Team team=(Team)session.get(Team.class,new Long(id));
       Hibernate.initialize(team.getMonkeys());
      tx.commit();
      return team;
    }catch (RuntimeException e) {
      if (tx != null) {
        tx.rollback();
      }
      throw e;
    } finally {
      session.close();
    }
  }

   public void test(){
      List jMonkeys=findAllJMonkeys();
      printAllMonkeys(jMonkeys.iterator());

      List monkeys=findAllMonkeys();
      printAllMonkeys(monkeys.iterator());

      Team team=loadTeam(1);
      printAllMonkeys(team.getMonkeys().iterator());

      Monkey monkey=new JMonkey("Mary","yellow",team);
      saveMonkey(monkey);

  }

  private void printAllMonkeys(Iterator it){
     while(it.hasNext()){
        Monkey m=(Monkey)it.next();
        if(m instanceof JMonkey)
          System.out.println(((JMonkey)m).getColor());
        else
          System.out.println(((CMonkey)m).getLength());
      }
  }
  public static void main(String args[]) {
    new BusinessService().test();
    sessionFactory.close();
  }
}

9.

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE hibernate-configuration
 PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
 "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
        <property name="dialect">
            org.hibernate.dialect.MySQLDialect
        </property>
        <property name="connection.driver_class">
            com.mysql.jdbc.Driver
        </property>
        <property name="connection.url">
            jdbc:mysql://localhost:3306/sampledb
        </property>
        <property name="connection.username">
            root
        </property>
        <property name="connection.password">
            1234
        </property>

        <property name="show_sql">true</property>

        <mapping resource="mypack/Team.hbm.xml" />
        <mapping resource="mypack/Monkey.hbm.xml" />
    </session-factory>
</hibernate-configuration>

10.

drop database if exists SAMPLEDB;
create database SAMPLEDB;
use SAMPLEDB;

create table TEAMS (
   ID bigint not null,
   NAME varchar(15),
   primary key (ID)
);
create table MONKEYS (
   ID bigint not null,
   NAME varchar(15),
   MONKEY_TYPE varchar(2),
   COLOR varchar(15),
   LENGTH double precision,
   TEAM_ID bigint,
   primary key (ID)
);

alter table MONKEYS add index IDX_TEAM(TEAM_ID), add constraint FK_TEAM foreign key (TEAM_ID) references TEAMS (ID);

insert into TEAMS(ID,NAME) values(1,'ABC Company');

insert into MONKEYS(ID,MONKEY_TYPE,NAME,COLOR,LENGTH,TEAM_ID) values(1,'JM','Tom','yellow',null,1);

insert into MONKEYS(ID,MONKEY_TYPE,NAME,COLOR,LENGTH,TEAM_ID) values(2,'JM','Mike','orange',null,1);

insert into MONKEYS(ID,MONKEY_TYPE,NAME,COLOR,LENGTH,TEAM_ID) values(3,'CM','Jack',null,1.2,1);

insert into MONKEYS(ID,MONKEY_TYPE,NAME,COLOR,LENGTH,TEAM_ID) values(4,'CM','Linda',null,2.0,1);