Hibernate逍遥游记-第13章 映射实体关联关系-004双向多对多(inverse="true")

1.

<?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="teachers" table="LEARNING"
        lazy="true"
        cascade="save-update">
        <key column="MONKEY_ID" />
        <many-to-many class="mypack.Teacher" column="TEACHER_ID" />
    </set>
       
  </class>

</hibernate-mapping>

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.Teacher" table="TEACHERS" >
    <id name="id" type="long" column="ID">
      <generator class="increment"/>
    </id>

    <property name="name" column="NAME" type="string" />
    
    <set name="monkeys" table="LEARNING"
        lazy="true"
        inverse="true"
        cascade="save-update">
        <key column="TEACHER_ID" />
        <many-to-many class="mypack.Monkey" column="MONKEY_ID" />
    </set>
 
  </class>
</hibernate-mapping>

3.

package mypack;

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

public class Monkey {
    private Long id;
    private String name;
    private Set teachers=new HashSet();
 
    public Monkey(String name, Set teachers) {
        this.name = name;
        this.teachers = teachers;
       
    }

    /** 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 getTeachers() {
        return this.teachers;
    }

    public void setTeachers(Set teachers) {
        this.teachers = teachers;
    }

 }

4.

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

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

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

    /** 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 getMonkeys() {
        return this.monkeys;
    }

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

 
}

5.

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 Monkey loadMonkey(Long id){
    Session session = sessionFactory.openSession();
    Transaction tx = null;
    try {
      tx = session.beginTransaction();
      Monkey monkey=(Monkey)session.get(Monkey.class,id);
      Hibernate.initialize(monkey.getTeachers());
      tx.commit();
      
      return monkey;

    }catch (RuntimeException e) {
      if (tx != null) {
        tx.rollback();
      }
      throw e;
    } finally {
      session.close();
    }
  }
   
  public void printMonkey(Monkey monkey){
    Set teachers=monkey.getTeachers();
    Iterator it=teachers.iterator();
    while(it.hasNext()){
      Teacher teacher=(Teacher)it.next();
      System.out.println(monkey.getName()+" "+teacher.getName());
    }
     
  }

 public void test(){
     
      Teacher teacher1=new Teacher("¶þÀÉÉñ");
      Teacher teacher2=new Teacher("ºìº¢¶ù");

      Monkey monkey1=new Monkey();
      monkey1.setName("ÖǶàÐÇ");
      monkey1.getTeachers().add(teacher1);
      monkey1.getTeachers().add(teacher2);
      teacher1.getMonkeys().add(monkey1);
      teacher2.getMonkeys().add(monkey1);

      Monkey monkey2=new Monkey();
      monkey2.setName("ÀÏÍçͯ");
      monkey2.getTeachers().add(teacher1);
      teacher1.getMonkeys().add(monkey2);

      saveMonkey(monkey1);
      saveMonkey(monkey2);

      monkey1=loadMonkey(monkey1.getId());
      printMonkey(monkey1);
      
  }

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

6.

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(
  MONKEY_ID bigint not null,
  TEACHER_ID bigint not null,
  primary key(MONKEY_ID,TEACHER_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);