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.