Hibernate逍遥游记-第13章 映射实体关联关系-006双向多对多(分解为一对多)

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>

   <property name="name" column="NAME" type="string" />
    
   <set name="learnings" lazy="true" inverse="true" cascade="save-update">
        <key column="MONKEY_ID" />
        <one-to-many  class="mypack.Learning" />
   </set>
     
  </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.Teacher" table="TEACHERS" >
    <id name="id" type="long" column="ID">
      <generator class="increment"/>
    </id>

    <property name="name" column="NAME" type="string" />
    
     <set name="learnings" lazy="true" inverse="true" cascade="save-update">
        <key column="TEACHER_ID" />
        <one-to-many  class="mypack.Learning" />
     </set>
 
  </class>
</hibernate-mapping>

4.

<?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.Learning" table="LEARNING" >
    <id name="id" type="long" column="ID">
      <generator class="increment"/>
    </id>

    <property name="gongfu" column="GONGFU" type="string" />
    
    <many-to-one name="monkey" column="MONKEY_ID" class="mypack.Monkey" not-null="true" />
    <many-to-one name="teacher" column="TEACHER_ID" class="mypack.Teacher" not-null="true" />

 
  </class>
</hibernate-mapping>

5.

package mypack;
import java.util.Set;
import java.util.HashSet;
import java.util.Iterator;

public class Monkey{


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

    public Monkey(String name, Set learnings) {
        this.name = name;
        this.learnings = learnings;
    }

    /** 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 Set getLearnings() {
        return this.learnings;
    }

    public void setLearnings(Set learnings) {
        this.learnings = learnings;
    }

 }

6.

package mypack;

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

public class Teacher{
    private Long id;
    private String name;
     private Set learnings=new HashSet();

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

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

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

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

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

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

    public Set getLearnings() {
        return this.learnings;
    }

    public void setLearnings(Set learnings) {
        this.learnings = learnings;
    }


}

7.

package mypack;
public class Learning{
    private Long id;
    private Teacher teacher;
    private Monkey monkey;
    private String gongfu;
    private int quantity;

    public Learning(Teacher teacher,Monkey monkey,String gongfu) {
        this.teacher= teacher;
        this.monkey = monkey;
        this.gongfu=gongfu;
    }

    /** default constructor */
    public Learning() {
    }
    
    public Long getId() {
        return this.id;
    }

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

    public String getGongfu() {
        return this.gongfu;
    }

    public void setGongfu(String gongfu) {
        this.gongfu = gongfu;
    }

    public Monkey getMonkey() {
        return this.monkey;
    }

    public void setMonkey(Monkey monkey) {
        this.monkey = monkey;
    }

    public Teacher getTeacher() {
        return this.teacher;
    }

    public void setTeacher(Teacher teacher) {
        this.teacher = teacher;
    }
    
  }

8.

package mypack;

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

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;
    try {
      tx = session.beginTransaction();
      session.save(monkey);
      tx.commit();

    }catch (RuntimeException e) {
      if (tx != null) {
        tx.rollback();
      }
      throw e;
    } finally {
      session.close();
    }
  }

  public void saveTeacher(Teacher teacher){
    Session session = sessionFactory.openSession();
    Transaction tx = null;
    try {
      tx = session.beginTransaction();
      session.save(teacher);
      tx.commit();

    }catch (RuntimeException e) {
      if (tx != null) {
        tx.rollback();
      }
      throw e;
    } finally {
      session.close();
    }
  }
 public Monkey loadMonkey(Long id){
    Session session = sessionFactory.openSession();
    Transaction tx = null;
    try {
      tx = session.beginTransaction();
      Monkey monkey=(Monkey)session.get(Monkey.class,id);
      Set learnings=monkey.getLearnings();
      Iterator it=learnings.iterator(); //初始化Learnings
      while(it.hasNext()){
        Learning learning=(Learning)it.next();
        Hibernate.initialize(learning.getTeacher()); //初始化Teacher
      }
      tx.commit();
      return monkey;

    }catch (RuntimeException e) {
      if (tx != null) {
        tx.rollback();
      }
      throw e;
    } finally {
      session.close();
    }
  }

  public void printMonkey(Monkey monkey){
    System.out.println("名字:"+monkey.getName());
 
    Set learnings=monkey.getLearnings();
    Iterator it=learnings.iterator();
    while(it.hasNext()){
      Learning learning=(Learning)it.next();
      System.out.println("-----------------------");
      System.out.println("老师:"+learning.getTeacher().getName());
      System.out.println("功夫:"+learning.getGongfu());
     }

  }

 public void test(){

      Teacher teacher1=new Teacher("二郎神",null);
      Teacher teacher2=new Teacher("红孩儿",null);
      saveTeacher(teacher1);
      saveTeacher(teacher2);

      Monkey monkey=new Monkey();
      monkey.setName("智多星");
      Learning learning1=new Learning(teacher1,monkey,"七十三变");
      Learning learning2=new Learning(teacher2,monkey,"三昧真火");
      
      monkey.getLearnings().add(learning1);
      monkey.getLearnings().add(learning2);
      saveMonkey(monkey);

      monkey=loadMonkey(monkey.getId());
      printMonkey(monkey);

  }

  public static void main(String args[]){
    new BusinessService().test();
    sessionFactory.close();
  }
}

9.

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

create table MONKEYS(
   ID bigint not null,
   NAME varchar(15),
   primary key (ID)
);

create table TEACHERS(
  ID bigint not null,
  NAME varchar(15),
  primary key(ID)
);

create table LEARNING(
  ID bigint not null,
  MONKEY_ID bigint not null,
  TEACHER_ID bigint not null,
  GONGFU varchar(15),
  primary key(ID)
);

alter table LEARNING add index IDX_MONKEY(MONKEY_ID), 
add constraint FK_MONKEY foreign key (MONKEY_ID) references MONKEYS(ID);

alter table LEARNING add index IDX_TEACHER(TEACHER_ID), 
add constraint FK_TEACHER foreign key (TEACHER_ID) references TEACHERS(ID);

10.