Hibernate学习（五）---【一对多单项】

Hibernate学习（五）---【一对多单项】

Classes和Student一对多。要站在classes这段来看。
classes.java

package  com.zzn.hibernate.oneToMany;

import  java.util.Set;

public   class  Classes {
     private   int  id;
     private  String name;
     private  Set students;

     public  Set getStudents() {
         return  students;
    }
     public   void  setStudents(Set students) {
         this .students  =  students;
    }
     public   int  getId() {
         return  id;
    }
     public   void  setId( int  id) {
         this .id  =  id;
    }
     public  String getName() {
         return  name;
    }
     public   void  setName(String name) {
         this .name  =  name;
    }
    
    
}

Student.java

package  com.zzn.hibernate.oneToMany;

public   class  Student  {
    private int id;
    private String name;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

Class.hbm.xml

<? 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  package ="com.zzn.hibernate.oneToMany" >
     < class  name ="Classes"  table ="CLASSES" >
         < id  name ="id"  column ="id" >
             < generator  class ="native"   />
         </ id >
         < property  name ="name"   />
         <!-- cascade="all"才能操作classes时级联操作student   -->
         < set  name ="students"  cascade ="all" >
             <!--  key 这里不能是not-null="true"  -->
             < key  column ="classesid" />
             < one-to-many  class ="Student" />
         </ set >
     </ class >
</ hibernate-mapping >

Student.hbm.xml

<? 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 ="com.zzn.hibernate.oneToMany.Student"  table ="STUDENT" >
         < id  name ="id"  column ="id" >
             < generator  class ="native"   />
         </ id >
         < property  name ="name"   />
     </ class >

</ hibernate-mapping >

test.java

package  com.zzn.hibernate;

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

import  junit.framework.TestCase;

import  org.hibernate.Session;
import  org.hibernate.Transaction;

import  com.zzn.hibernate.hibernateUtil.HibernateUtils;
import  com.zzn.hibernate.oneToMany.Classes;
import  com.zzn.hibernate.oneToMany.Student;

public   class  OneToManyTest  extends  TestCase {
    
    @SuppressWarnings( " unchecked " )
     public   void  OneToManySave() {
        Session session  =   null ;
        Transaction tx  =   null ;
         try  {
            session  =  HibernateUtils.getSession();
            tx  =  session.beginTransaction();
            
            Student student1  =   new  Student();
            student1.setName( " 刘德华 " );
            Student student2  =   new  Student();
            student2.setName( " 周杰伦 " );

            Set students  =   new  HashSet();
            students.add(student1);
            students.add(student2);
            
            Classes classes  =   new  Classes();
            classes.setName( " 中国 " );
            classes.setStudents(students);
            
            session.save(classes);
            
        }  catch  (Exception e) {
            e.printStackTrace();
        }  finally  {
             if  (session  !=   null ) {
                 if  (session.isOpen()) {
                    tx.commit();
                    session.close();
                }
            }
        }
    }
    
    @SuppressWarnings( " unchecked " )
     public   void  OneToManyLoad() {
        Session session  =   null ;
        Transaction tx  =   null ;
         try  {
            session  =  HibernateUtils.getSession();
            tx  =  session.beginTransaction();
            Classes classes  =  (Classes)session.load(Classes. class ,  1 );
            Set students  =  classes.getStudents();
             for  (Iterator iter = students.iterator(); iter.hasNext();){
                Student student  =  (Student)iter.next();
                System.out.println( " student.name= " + student.getName());
            }
            
        }  catch  (Exception e) {
            e.printStackTrace();
        }  finally  {
             if  (session  !=   null ) {
                 if  (session.isOpen()) {
                    tx.commit();
                    session.close();
                }
            }
        }
    }
}