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hibernate繼承---聯(lián)合子類(lèi) 已更新(六)

這篇和上一篇http://www.aygfsteel.com/wujun/archive/2006/04/11/40527.html
不同的地方在于配置文件上。
上一篇采用的是joined-subclass?

先看先看由滿(mǎn)江紅翻譯團(tuán)隊(duì)(RedSaga Translate Team)翻譯的聯(lián)合子類(lèi)說(shuō)明..

<union-subclass
        name="ClassName"                    (1)
        table="tablename"                   (2)
        proxy="ProxyInterface"              (3)
        lazy="true|false"                   (4)
        dynamic-update="true|false"
        dynamic-insert="true|false"
        schema="schema"
        catalog="catalog"
        extends="SuperclassName"
        abstract="true|false"
        persister="ClassName"
        subselect="SQL expression"
        entity-name="EntityName"
        node="element-name">

        <property .... />
        .....
</union-subclass>

(1)	`name`: 子類(lèi)的全限定名。
(2)	`table`: 子類(lèi)的表名
(3)	`proxy` (可選): 指定一個(gè)類(lèi)或者接口，在延遲裝載時(shí)作為代理使用。
(4)	`lazy` (可選, 默認(rèn)是 `true`): 設(shè)置為 `lazy="false"` 禁止使用延遲裝載。

這種映射策略不需要指定辨別標(biāo)志(discriminator)字段。

更多關(guān)于繼承映射的信息，參考第?10?章 繼承映射(Inheritance Mappings)。

好了。。看一個(gè)例子
看這個(gè)配置文件

<? xml?version="1.0" ?>

<! DOCTYPE?hibernate-mapping

????PUBLIC?"-//Hibernate/Hibernate?Mapping?DTD//EN"

????"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >

< hibernate-mapping >

???? < class? name ="com.test.Dog" ?table ="dog" > ??

???????? < id? name ="aid" ?type ="string" ?unsaved-value ="null" ? >

???????????? < column? name ="aid" ?sql-type ="char(32)" ?not-null ="true" />

???????????? < generator? class ="uuid.hex" />

???????? </ id >

???????? < property? name ="dname" >

???????????? < column? name ="dname" ?sql-type ="varchar(16)" />

???????? </ property >

???? </ class >

???? < class? name ="com.test.Cat" ?table ="cat" > ??

???????? < id? name ="aid" ?type ="string" ?unsaved-value ="null" ? >

???????????? < column? name ="aid" ?sql-type ="char(32)" ?not-null ="true" />

???????????? < generator? class ="uuid.hex" />

???????? </ id >

???????? < property? name ="cname" >

???????????? < column? name ="cname" ?sql-type ="varchar(16)" />

???????? </ property >

???? </ class >

</ hibernate-mapping >

表結(jié)構(gòu):

create ? table ?dog

(aid? varchar ( 32 )? not ? null ? primary ? key ,

?dname? varchar ( 16 )

)

create ? table ?cat

(aid? varchar ( 32 )? not ? null ? primary ? key ,

?cname? varchar ( 16 )

)

寫(xiě)VO
Amimal.java

package ?com.test;

public ? class ?Animal

{

???? private ?String?aid;

??? // get?set

Dog.java

package ?com.test;

public ? class ?Dog? extends ?Animal

{

???? private ?String?dname;

?? // get?set

Cat.java

package?com.test;

public?class?Cat?extends?Animal

{

????private?String?cname;

??//get?set

測(cè)試。。。

//插入

????public?void?doCreate()

????{

????????try

????????{

????????????session?=?sf.openSession();

????????????Dog?dog?=?new?Dog();

????????????dog.setDname("small?dog");

????????????Cat?cat?=?new?Cat();

????????????cat.setCname("small?cat");

????????????session.save(dog);

????????????session.save(cat);

????????????session.flush();

????????????session.connection().commit();

????????}

????????catch(HibernateException?ex)

????????{

????????????ex.printStackTrace();

????????}

????????catch(SQLException?ex1)

????????{

????????????ex1.printStackTrace();

????????}

????????finally

????????{

????????????????try{

????????????????????session.close();

????????????????}

????????????????catch(HibernateException?ex2){

????????????????}

????????}

????}

????//查詢(xún)

????public?void?doQuery()

????{

????????try{

????????????session?=?sf.openSession();

????????????Query?q?=?session.createQuery("select?d?from?Dog?as?d");

????????????List?l?=?q.list();

????????????Dog?dog?=?null;

????????????Cat?cat?=?null;

????????????for(int?i=0;i<l.size();i++)

????????????{

????????????????dog?=?(Dog)l.get(i);

????????????????System.out.println(dog.getDname());

????????????}

????????}

????????catch(HibernateException?ex){

????????????ex.printStackTrace();

????????}

????????finally{

????????????try{

????????????????session.close();

????????????}

????????????catch(HibernateException?ex2){

????????????}

????????}

????}

posted on 2006-04-14 21:50 record java and net 閱讀(593) 評(píng)論(0) 編輯收藏所屬分類(lèi): java

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