Hibernate實作Table per class hierarchy例子

說明：利用category欄位來區分商品類別，如此一來不管是Book或是DVD皆可以存放在此Table中。Table per class hierarchy:表與類別的一對多關係。




1.建立t_item表格：


drop table if exists t_item;



create table t_item(

id int(11) auto_increment,

category varchar(10) not null default '',

name varchar(50) default '',

manufacture varchar(50) default '',

regioncode varchar(30) default '',

pagecount int(11),

primary key(id));





2.建立TItem.java及TItem.hbm.xml，其內容分別如下：


package org.redsaga.quickstart;




// Generated 2009/8/6 下午 11:08:15 by Hibernate Tools 3.2.4.GA




/**

 * TItem generated by hbm2java

 */

public class TItem implements java.io.Serializable {




 private Integer id;

 private String category;

 private String name;

 private String manufacture;




 public TItem() {

 }




 public TItem(String category) {

  this.category = category;

 }




 public TItem(String category, String name, String manufacture) {

  this.category = category;

  this.name = name;

  this.manufacture = manufacture;

 }




 public Integer getId() {

  return this.id;

 }




 public void setId(Integer id) {

  this.id = id;

 }




 public String getCategory() {

  return this.category;

 }




 public void setCategory(String category) {

  this.category = category;

 }




 public String getName() {

  return this.name;

 }




 public void setName(String name) {

  this.name = name;

 }




 public String getManufacture() {

  return this.manufacture;

 }




 public void setManufacture(String manufacture) {

  this.manufacture = manufacture;

 }

}

==================================


<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<!-- Generated 2009/8/6 ?U?? 11:08:15 by Hibernate Tools 3.2.4.GA -->

<hibernate-mapping>

    <class name="org.redsaga.quickstart.TItem" table="t_item" catalog="manning">

        <id name="id" type="java.lang.Integer">

            <column name="id" />

            <generator class="identity" />

        </id>

 <discriminator column="category" length="10" type="string" not-null="true"/>

        <property name="name" type="string">

            <column name="name" length="50" />

        </property>

        <property name="manufacture" type="string">

            <column name="manufacture" length="50" />

        </property>

<subclass name="org.redsaga.quickstart.TDVD" discriminator-value="2">

         <property name="regioncode" type="string">

             <column name="regioncode" length="30" />

         </property>

        </subclass>

<subclass name="org.redsaga.quickstart.TBook" discriminator-value="1">

         <property name="pagecount" type="java.lang.Integer">

             <column name="pagecount" />

         </property>

     </subclass>

    </class>

</hibernate-mapping>

=====================================




3.建立TBook.java及TDVD.java，其內容分別如下：


package org.redsaga.quickstart;




public class TBook extends TItem implements java.io.Serializable {

 private Integer pagecount;

 


 public TBook(){

  


 }

 


 public Integer getPagecount() {

  return this.pagecount;

 }




 public void setPagecount(Integer pagecount) {

  this.pagecount = pagecount;

 } 


}

====================================


package org.redsaga.quickstart;




public class TDVD extends TItem implements java.io.Serializable {

 private String regioncode;

 


 public TDVD(){

  


 }

 


 public String getRegioncode() {

  return this.regioncode;

 }




 public void setRegioncode(String regioncode) {

  this.regioncode = regioncode;

 }

}

======================================




4.修改Hibnerate.cfg.xml：


<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-configuration PUBLIC

  "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

  "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <property name="hibernate.connection.driver_class">org.gjt.mm.mysql.Driver</property>

        <property name="hibernate.connection.password">action</property>

        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/manning</property>

        <property name="hibernate.connection.username">manning</property>

        <property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>

        <!-- 將SQL輸出到Console --> 

        <property name="hibernate.show_sql">true</property>

        <!-- 使用JDBC Transaction  -->

        <property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property>

        <!-- 將TUser.hbm.xml加到Hibernate.cfg.xml檔案中 -->

        <mapping resource="org/redsaga/quickstart/TUser.hbm.xml"/>

        <!-- 將TItem.hbm.xml加到Hibernate.cfg.xml檔案中 -->

<mapping resource="org/redsaga/quickstart/TItem.hbm.xml"/>

    </session-factory>

</hibernate-configuration>

=====================================




5.建立JUnit測試Method(testItem)，內容如下：


 /**

  * testItem Table per class hierarchy練習

  * @throws Exception

  */

 public void testItem() throws Exception {

  Transaction tran = null;

  TBook book = null;

  TDVD dvd = null;

  List list = null;

  Iterator it = null;

  try{




   tran = session.beginTransaction();

   //新增書籍資料

   book = new TBook();

   book.setCategory("1");

   book.setName("倚天屠龍記");

   book.setManufacture("金庸");

   book.setPagecount(288);

   session.save(book);

   session.flush();

   tran.commit();

   tran = session.beginTransaction();

   //新增DVD資料   


   dvd = new TDVD();

   dvd.setCategory("2");

   dvd.setName("今天不回家");

   dvd.setManufacture("全家");

   dvd.setRegioncode("亞洲");

   session.save(dvd);

   session.flush();

   tran.commit();




   //查詢 TBook資料

   list = session.createQuery(" from TBook").list();

   it = list.iterator();

   while(it.hasNext()){

    book = (TBook)it.next();

    System.out.println("Book:"+book.getName()+","+book.getManufacture()+","+book.getPagecount());

   }

   //查詢 TDVD資料

   list = session.createQuery(" from TDVD").list();

   it = list.iterator();

   while(it.hasNext()){

    dvd = (TDVD)it.next();

    System.out.println("DVD:"+dvd.getName()+","+dvd.getManufacture()+","+dvd.getRegioncode());

   }

  }catch(HibernateException e){

   e.printStackTrace();

  }

 }

==================================




6.測試結果：

MySql查詢結果：




console輸出結果：


Hibernate: insert into manning.t_item (name, manufacture, pagecount, category) values (?, ?, ?, '1')

Hibernate: insert into manning.t_item (name, manufacture, regioncode, category) values (?, ?, ?, '2')

Hibernate: select tbook0_.id as id1_, tbook0_.name as name1_, tbook0_.manufacture as manufact4_1_, tbook0_.pagecount as pagecount1_ from manning.t_item tbook0_ where tbook0_.category='1'

Book:倚天屠龍記,金庸,288

Hibernate: select tdvd0_.id as id1_, tdvd0_.name as name1_, tdvd0_.manufacture as manufact4_1_, tdvd0_.regioncode as regioncode1_ from manning.t_item tdvd0_ where tdvd0_.category='2'

DVD:今天不回家,全家,亞洲