Hibernate入门教程 Hibernate关系映射详解-hibernate教程

Hibernate关系映射是1对1one-to-one。

1对1的关系在现实中很常见。比方说：人和身份证。1个身份证对应着一个身份证，一个身份证对应着一个人。那么，我们就以此为原型。进行代码编写。

建立实体模型如右：

根据模型，创建数据库：

    useHibernateQuickUse;
droptableifexistsPerson;
droptableifexistsCard;

createtableCard(
idvarchar(32)primarykey,
cardDescvarchar(128)notnull
);

createtablePerson(
idvarchar(32)primarykey,
namevarchar(32)notnull,
card_idvarchar(32)notnull,
foreignkey(card_id)referencesCard(id)
);

Java代码如下：

Person类

   packageorg.py.hib.relation.one2one;

/**
*Personentity.
*/

@SuppressWarnings("serial")
publicclassPersonimplementsjava.io.Serializable
{
privateStringid;

privateStringname;

privateCardcard;

publicPerson()
{
}

publicStringgetId()
{
returnthis.id;
}

publicvoidsetId(Stringid)
{
this.id=id;
}

publicCardgetCard()
{
returnthis.card;
}

publicvoidsetCard(Cardcard)
{
this.card=card;
}

publicStringgetName()
{
returnthis.name;
}

publicvoidsetName(Stringname)
{
this.name=name;
}

Card类：

    packageorg.py.hib.relation.one2one;

/**
*Cardentity.
*/

@SuppressWarnings("serial")
publicclassCardimplementsjava.io.Serializable
{
privateStringid;

privateStringcardDesc;

publicCard()
{
}

publicStringgetId()
{
returnthis.id;
}

publicvoidsetId(Stringid)
{
this.id=id;
}

publicStringgetCardDesc()
{
returncardDesc;
}

publicvoidsetCardDesc(StringcardDesc)
{
this.cardDesc=cardDesc;
}
}

XML映射文件如下：

Person.hbm.xml

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

cascade="all"column="card_id"/>

今天讲的是one-to-one配置。但是，此处用的是many-to-one，这个是什么原因呢？其实，one-to-one就是特殊的many-to-one。

Card.hbm.xml：

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

#p#

测试代码如下：

One2OneTest.java

    packageorg.py.hib.relation.one2one;

importjunit.framework.Assert;
importjunit.framework.TestCase;

importorg.hibernate.Session;
importorg.hibernate.SessionFactory;
importorg.hibernate.Transaction;
importorg.hibernate.cfg.Configuration;
importorg.junit.After;
importorg.junit.Before;

publicclassOne2OneTestextendsTestCase
{
privateSessionFactoryfactory;

privateStringm_name="ryanpoy";

privateStringm_name2="ryanpoy2";

privateStringm_cardDesc1="desc_1";

privateStringm_cardDesc2="desc_2";

@Before
publicvoidsetUp()throwsException
{
Configurationconf=newConfiguration().configure();
factory=conf.buildSessionFactory();
}

/**
*测试添加
*@throwsException
*/
publicvoidtestSave()throwsException
{
System.out.println("\n===testsave===");

Cardcard=newCard();
card.setCardDesc(m_cardDesc1);

Personperson=newPerson();
person.setName(m_name);//设置用户名=m_name
person.setCard(card);

Sessionsession=null;
Transactiontran=null;
try
{
session=factory.openSession();
tran=session.beginTransaction();
session.save(person);

tran.commit();

Assert.assertEquals(person.getId()!=null,true);
Assert.assertEquals(card.getId()!=null,true);

}catch(Exceptionex)
{
tran.rollback();
throwex;
}finally
{
if(session!=null)
{
try
{
session.close();
}catch(Exceptionex)
{
//nothingtodo
}finally
{
if(session!=null)
session=null;
}
}
}
}

/**
*测试查询
*@throwsException
*/
publicvoidtestFind()throwsException
{
System.out.println("\n===testfind===");
Sessionsession=null;
try
{
session=factory.openSession();
Personperson=(Person)session.createQuery("fromPerson").list().get(0);

Assert.assertEquals(true,person.getId()!=null);
Assert.assertEquals(m_name,person.getName());

Assert.assertEquals(true,person.getCard().getId()!=null);
Assert.assertEquals(m_cardDesc1,person.getCard().getCardDesc());

}catch(Exceptionex)
{
throwex;
}finally
{
if(session!=null)
{
try
{
session.close();
}catch(Exceptionex)
{
//nothingtodo
}finally
{
if(session!=null)
session=null;
}
}
}
}

/**
*测试修改
*@throwsException
*/
publicvoidtestModify()throwsException
{
System.out.println("\n===testmodify===");
Sessionsession=null;
Transactiontran=null;
try
{
session=factory.openSession();
tran=session.beginTransaction();

Personperson=(Person)session.createQuery("fromPerson").list().get(0);
person.setName(m_name2);//修改用户名=m_name2.（原来用户名=m_name）
person.getCard().setCardDesc(m_cardDesc2);//修改cardDesc为m_cardDesc2(原来是：m_cardDesc1)
tran.commit();

}catch(Exceptionex)
{
throwex;
}finally
{
if(session!=null)
{
try
{
session.close();
}catch(Exceptionex)
{
//nothingtodo
}finally
{
if(session!=null)
session=null;
}
}
}

/*
*修改后再查询
*/
System.out.println("\n===testfindaftermodify===");
try
{
session=factory.openSession();
Personperson=(Person)session.createQuery("fromPerson").list().get(0);

Assert.assertEquals(true,person.getId()!=null);
Assert.assertEquals(m_name2,person.getName());

Assert.assertEquals(true,person.getCard().getId()!=null);
Assert.assertEquals(m_cardDesc2,person.getCard().getCardDesc());

}catch(Exceptionex)
{
throwex;
}finally
{
if(session!=null)
{
try
{
session.close();
}catch(Exceptionex)
{
//nothingtodo
}finally
{
if(session!=null)
session=null;
}
}
}
}

/**
*测试删除
*@throwsException
*/
publicvoidtestDelete()throwsException
{
System.out.println("\n===testdelete===");
Sessionsession=null;
Transactiontran=null;
try
{
session=factory.openSession();
tran=session.beginTransaction();

Personperson=(Person)session.createQuery("fromPerson").list().get(0);
session.delete(person);
tran.commit();

}catch(Exceptionex)
{
throwex;
}finally
{
if(session!=null)
{
try
{
session.close();
}catch(Exceptionex)
{
//nothingtodo
}finally
{
if(session!=null)
session=null;
}
}
}

/*
*删除后再查询
*/
System.out.println("\n===testfindafterdelete===");
try
{
session=factory.openSession();

Integernum=(Integer)session.createQuery("fromPerson").list().size();
Assert.assertEquals(0,num.intValue());

num=(Integer)session.createQuery("fromCard").list().size();
Assert.assertEquals(0,num.intValue());

}catch(Exceptionex)
{
throwex;
}finally
{
if(session!=null)
{
try
{
session.close();
}catch(Exceptionex)
{
//nothingtodo
}finally
{
if(session!=null)
session=null;
}
}
}
}

/**
*
*/
@After
publicvoidtearDown()throwsException
{
factory.close();
}

运行test，测试成功.

在Hibernateone-to-one关系映射中，其实还有一种方式，即：唯一主见关联。但是，我一直倾向于上面的这种形式，所以，唯一主见关联的旧部介绍了。

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