Hibernate实体层次设计(二)

Hibernate实体层次设计(二)

Table per concrete class方式:

TItem有两个子类：TBook、TDVD。按照Table per concrete class方式，每个字类对应一张数据库表。对应于TBook和TDVD，我们有以下库表：

1.数据库库表
T_Book.sql

DROP   TABLE  T_Book;

CREATE   TABLE  T_Book (
       id  INT   NOT   NULL  AUTO_INCREMENT
     , name  VARCHAR ( 50 )
     , manufacturer  VARCHAR ( 50 )
     , pagecount  INT
     ,  PRIMARY   KEY  (id)
);

T_DVD.sql

DROP   TABLE  T_DVD;

CREATE   TABLE  T_DVD (
       id  INT   NOT   NULL  AUTO_INCREMENT
     , name  VARCHAR ( 50 )
     , manufacturer  VARCHAR ( 50 )
     , regioncode  VARCHAR ( 30 )
     ,  PRIMARY   KEY  (id)
);

2.配置文件
配置文件和普通配置文件没有区别

TBook.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 ="cn.blogjava.start" >
     < class  name ="TBook"  table ="T_Book"  catalog ="sample" >
         < id  name ="id"  column ="id"  type ="java.lang.Integer" >
             < generator  class ="native"   />
         </ id >

         < property  name ="name"  type ="java.lang.String"  column ="name" />
         < property  name ="manufacturer"  type ="java.lang.String"  column ="manufacturer" />         
         < property  name ="pageCount"  type ="java.lang.Integer"  column ="pagecount" />         
     </ class >
</ hibernate-mapping >

TDVD.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 ="cn.blogjava.start" >
     < class  name ="TDVD"  table ="T_DVD"  catalog ="sample" >
         < id  name ="id"  column ="id"  type ="java.lang.Integer" >
             < generator  class ="native"   />
         </ id >

         < property  name ="name"  type ="java.lang.String"  column ="name" />
         < property  name ="manufacturer"  type ="java.lang.String"  column ="manufacturer" />         
         < property  name ="regionCode"  type ="java.lang.String"  column ="regioncode" />         
     </ class >
</ hibernate-mapping >

3.测试代码
HibernateTest.java

package  cn.blogjava.start;

import  java.util.Iterator;
import  java.util.List;

import  junit.framework.Assert;
import  junit.framework.TestCase;

import  org.hibernate.HibernateException;
import  org.hibernate.Session;
import  org.hibernate.SessionFactory;
import  org.hibernate.Transaction;
import  org.hibernate.cfg.Configuration;


public   class  HibernateTest  extends  TestCase {
    
    Session session  =   null ;
     /**
     * JUnit中的setUp方法在TestCase初始化的时候会自动调用
     * 一般用于初始化公用资源
      */
     protected   void  setUp() {
         try  {
             /**
             * 可以采用hibernate.properties或者hibernate.cfg.xml
             * 配置文件的初始化代码
             * 
             * 采用hibernate.properties
             * Configuration config = new Configuration()；
             * config.addClass(TUser.class);
              */
            
             // 采用hibernate.cfg.xml配置文件，与上面的方法对比，两个差异
             // 1.Configuration的初始化方式
             // 2.xml
            Configuration config  =   new  Configuration().configure();
            SessionFactory sessionFactory  =  config.buildSessionFactory();
            session  =  sessionFactory.openSession();
            
        }  catch  (HibernateException e) {
             //  TODO: handle exception
            e.printStackTrace();
        }        
    }

     /**
     * JUnit中的tearDown方法在TestCase执行完毕的时候会自动调用
     * 一般用于释放资源
      */     
     protected   void  tearDown() {
         try  {
            session.close();        
        }  catch  (HibernateException e) {
             //  TODO: handle exception
            e.printStackTrace();
        }        
    }    
    
     /**
     * 对象持久化测试(Insert方法)
      */         
     public   void  testInsert() {
        Transaction tran  =   null ;
         try  {
            tran  =  session.beginTransaction();
            TBook book1  =   new  TBook();
            
            book1.setManufacturer( " 电子工业 " );
            book1.setName( " Java beginner " );
            book1.setPageCount( 501 );
            
            TBook book2  =   new  TBook();
            book2.setManufacturer( " 机械工业 " );
            book2.setName( " Thinking in java " );
            book2.setPageCount( 1201 );
            
            TDVD dvd1  =   new  TDVD();
            dvd1.setManufacturer( " columnibia " );
            dvd1.setName( " Lord king " );
            dvd1.setRegionCode( " 5 area " );
            
            TDVD dvd2  =   new  TDVD();
            dvd2.setManufacturer( " sony " );
            dvd2.setName( " Forrest gump " );
            dvd2.setRegionCode( " 3 area " );            

            session.save(book1);
            session.save(book2);
            session.save(dvd1);
            session.save(dvd2);
            session.flush();
            tran.commit();
            Assert.assertEquals(book1.getId().intValue() > 0 ,  true );
            Assert.assertEquals(book2.getId().intValue() > 0 ,  true );
            Assert.assertEquals(dvd1.getId().intValue() > 0 ,  true );
            Assert.assertEquals(dvd2.getId().intValue() > 0 ,  true );
        }  catch  (HibernateException e) {
             //  TODO: handle exception
            e.printStackTrace();
            Assert.fail(e.getMessage());
             if (tran  !=   null ) {
                 try  {
                    tran.rollback();
                }  catch  (Exception e1) {
                     //  TODO: handle exception
                    e1.printStackTrace();
                }
            }
        }
    }
    
     /**
     * 对象读取测试(Select方法)
      */             
     public   void  testSelect(){

        //指定了具体父类，如果是from TItem，是会失败的。
        List list  =  session.createQuery( "  from cn.blogjava.start.TItem " ).list();
        
        Iterator it  =  list.iterator();
         while  (it.hasNext()) {
            TItem item  =  (TItem)it.next();
            System.out.println(item.getName());
            
        }
    }
}