hibernate入门使用系列 5 -- xml关系映射篇（补充1）

由于最近一段时间比较忙。一直被手中的项目牵着。所以，也就没有时间来写点东西。终于项目差不多了。

 

本来对于hibernate的关系映射不打算再说了。不过前3篇的关系映射都是最原始的。在实际中，可能会有较为复杂的关系。
比方说：customers一对多于orders，同时一对一于address，这样的三表关联。

所以，再写一遍1对多和1对1同时存在的。

先看实际场景。不用上面的，用一个新的。
比方说：丈夫有1个妻子，这样是1夫1妻。但是，丈夫花心，同时有多个情妇。

例子归例子，大家不要做这样的丈夫。只是为了更加深入记忆。

先看sql：

 

use HibernateQuickUse;

drop table if exists Paramour;
drop table if exists Husband;
drop table if exists Wife;

create table Wife (
	wid varchar(32) primary key,
	name varchar(128) not null
);


create table Husband (
	hid varchar(32) primary key,
	name varchar(32) not null,
	wife_id varchar(32) not null,
	foreign key(wife_id) references Wife(wid)
);

create table Paramour (
	pid varchar(32)  primary key,
	name varchar(128) not null,
	husband_id varchar(32) not null,
	foreign key(husband_id) references Husband(hid)
);

 

然后看java文件。

Husband.java

 

package org.py.hib.relation.complex;

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

@SuppressWarnings("serial")
public class Husband implements java.io.Serializable
{
	private String id;

	private String name;

	private Wife wife;

	private Set<Paramour> paramours = new HashSet<Paramour>();

	/** default constructor */
	public Husband()
	{
	}

	public String getId()
	{
		return id;
	}

	public void setId(String id)
	{
		this.id = id;
	}

	public String getName()
	{
		return name;
	}

	public void setName(String name)
	{
		this.name = name;
	}

	public Wife getWife()
	{
		return wife;
	}

	public void setWife(Wife wife)
	{
		this.wife = wife;
	}

	public Set<Paramour> getParamours()
	{
		return paramours;
	}

	public void setParamours(Set<Paramour> paramours)
	{
		this.paramours = paramours;
	}
}

 

Wife.java

package org.py.hib.relation.complex;

@SuppressWarnings("serial")
public class Wife implements java.io.Serializable
{
	private String id;

	private String name;

	/** default constructor */
	public Wife()
	{
	}

	public String getId()
	{
		return id;
	}

	public void setId(String id)
	{
		this.id = id;
	}

	public String getName()
	{
		return this.name;
	}

	public void setName(String name)
	{
		this.name = name;
	}

}

 

Paramour.java

 

package org.py.hib.relation.complex;

@SuppressWarnings("serial")
public class Paramour implements java.io.Serializable
{
	private String id;

	private String name;

	private Husband husband;

	/** default constructor */
	public Paramour()
	{
	}

	public String getId()
	{
		return id;
	}

	public void setId(String id)
	{
		this.id = id;
	}

	public Husband getHusband()
	{
		return this.husband;
	}

	public void setHusband(Husband husband)
	{
		this.husband = husband;
	}

	public String getName()
	{
		return this.name;
	}

	public void setName(String name)
	{
		this.name = name;
	}

}

 

 

接下来再看xml映射文件。

Husband.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
	<class name="org.py.hib.relation.complex.Husband" table="husband">
		<id name="id" type="java.lang.String" column="hid"
			length="32">
			<generator class="uuid" />
		</id>

		<property name="name" type="java.lang.String" column="name"
			length="32" not-null="true" />

		<many-to-one name="wife" class="org.py.hib.relation.complex.Wife" cascade="all" column="wife_id" />
			
		<set name="paramours" cascade="all" inverse="true" >
			<key column="husband_id" />
			<one-to-many class="org.py.hib.relation.complex.Paramour" />
		</set>
	</class>
</hibernate-mapping>

 

 

Wife.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
	<class name="org.py.hib.relation.complex.Wife" table="wife">
		<id name="id" type="java.lang.String" column="wid" length="32">
			<generator class="uuid" />
		</id>

		<property name="name" type="java.lang.String" column="name"	length="128" not-null="true" />

	</class>
</hibernate-mapping>

 

Paramour.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
	Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
	<class name="org.py.hib.relation.complex.Paramour" table="paramour">
		<id name="id" type="java.lang.String" column="pid">
			<generator class="uuid" />
		</id>

		<property name="name" type="java.lang.String" column="name" not-null="true" />

		<many-to-one name="husband" class="org.py.hib.relation.complex.Husband" column="husband_id" />
		
	</class>
	
</hibernate-mapping>

 

 

 

因为时间关系，只测试了save。其他的测试大家感兴趣的可以补充。

 

 ComplexTest.java

package org.py.hib.relation.complex;

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

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.After;
import org.junit.Before;

/**
 * 这个测试忽略了hibernate的异常
 */
public class ComplexTest extends TestCase
{
	private SessionFactory factory;

	@Before
	public void setUp() throws Exception
	{
		Configuration conf = new Configuration().configure();
		factory = conf.buildSessionFactory();
	}

	public void testSave()
	{
		Session session = factory.openSession();
		Transaction tran = session.beginTransaction();

		Husband hus = new Husband();
		hus.setName("husband");

		Wife wife = new Wife();
		wife.setName("wife");

		Paramour p1 = new Paramour();
		p1.setName("paramour_1");

		Paramour p2 = new Paramour();
		p2.setName("paramour_2");

		Paramour p3 = new Paramour();
		p3.setName("paramour_3");

		hus.setWife(wife);

		hus.getParamours().add(p1);
		hus.getParamours().add(p2);
		hus.getParamours().add(p3);

		p1.setHusband(hus);
		p2.setHusband(hus);
		p3.setHusband(hus);
		
		session.save(hus);

		tran.commit();

		Assert.assertNotNull(hus.getId());
		Assert.assertNotNull(wife.getId());

		Assert.assertNotNull(p1.getId());
		Assert.assertNotNull(p2.getId());
		Assert.assertNotNull(p3.getId());
		
		session.close();
	}

	@After
	public void tearDown()
	{
		factory.close();
	}
}

 

 

 

其实，这个例子仍然很简单，且无实用性。因为时间的关系，呵呵。就写到这里。

 

 

 附件里面是源代码。

 

 

好，不错。能不能加一个查询的内容，三表关联的查询怎么做？谢谢！

我也要个查询的，麻烦做个

lz可以介绍下你们项目当中是怎么运用hibernate的嘛.

数据量多大?性能如何?

3表查询和2表关联查询是一样的。

每天7kw的记录。
从log来看，查询平均在5秒内。
但是我们的系统并发少。
从实际的应用来看。我们的检索采用了hibernate。
而加载采用了mysql的自带loaddata的方式。可以看blog里面的mysql分类下的一篇。

  hus.setWife(wife);   
  
        hus.getParamours().add(p1);   
        hus.getParamours().add(p2);   
        hus.getParamours().add(p3);   
  
        p1.setHusband(hus);   
        p2.setHusband(hus);   
        p3.setHusband(hus);   
           
        session.save(hus);  

这其中hus在session.save操作后变成了持久化对象，但是wife和p1,p2,p3都是临时对象，它们是怎么被级联更新了呢？也就是cascade在配置文件里该怎么用？大侠能否帮忙解释下？谢谢！

你可以参看 http://www.iteye.com/topic/190679。这个里面有提到。