<?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>

 <?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>

 <?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>

 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;

     }

  }

 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;

     }

 }

 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;

     }

   }

 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();

   }

 }

 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);