Hibernate逍遥游记-第13章 映射实体关联关系-003单向多对多

 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);

 <?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>

 <?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" />

   </class>

 </hibernate-mapping>

 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;

     }

  }

 package mypack;

 public class Teacher{

     private Long id;

     private String name;

     /** 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;

     }

 }

 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);

       Monkey monkey2=new Monkey();

       monkey2.setName("ÀÏÍçͯ");

       monkey2.getTeachers().add(teacher1);

       saveMonkey(monkey1);

       saveMonkey(monkey2);

       monkey1=loadMonkey(monkey1.getId());

       printMonkey(monkey1);

   }

   public static void main(String args[]){

     new BusinessService().test();

     sessionFactory.close();

   }

 }