Hibernate4Step5

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hardwork

本着应用的目的快速学习Hibernate4框架

  • Hibernate映射继承

前面的话

本节主要介绍：

本文主要讲解Hibernate4的映射继承，主要包括如下：

  1. 每个子类对应一个表
  2. 只有一个基类对应一个表
  3. 每个类对应一个表

Type1：每个子类对应一个表

Demo：建立一个抽象类Picture，并由两个子类LifePic和WorkPic继承该类，每个员工Staff有多个Picture。

Type1.mgc

类图关系如下：
1.mgc

Picture.java

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package cn.codeforgod.model;

public abstract class Picture
{
	private long id;
	private String name;
	private Staff staff;
	
	public long getId()
	{
		return id;
	}
	public void setId(long id)
	{
		this.id = id;
	}
	public String getName()
	{
		return name;
	}
	public void setName(String name)
	{
		this.name = name;
	}
	public Staff getStaff()
	{
		return staff;
	}
	public void setStaff(Staff staff)
	{
		this.staff = staff;
	}
}

LifePic.java

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package cn.codeforgod.model;

public class LifePic extends Picture
{
	private String note;	// 备注

	public String getNote()
	{
		return note;
	}

	public void setNote(String note)
	{
		this.note = note;
	}
}

WorkPic.java

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package cn.codeforgod.model;

public class WorkPic extends Picture
{
	private String company;	// 公司名称

	public String getCompany()
	{
		return company;
	}

	public void setCompany(String company)
	{
		this.company = company;
	}
}

Staff.java

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package cn.codeforgod.model;

import java.util.Set;

public class Staff
{
	private int id;
	private String name;
	private Set<Picture> pics;
	
	public int getId()
	{
		return id;
	}
	public void setId(int id)
	{
		this.id = id;
	}
	public String getName()
	{
		return name;
	}
	public void setName(String name)
	{
		this.name = name;
	}
	public Set<Picture> getPics()
	{
		return pics;
	}
	public void setPics(Set<Picture> pics)
	{
		this.pics = pics;
	}
	@Override
	public String toString()
	{
		return "Staff [id=" + id + ", name=" + name + ", pics=" + pics + "]";
	}
	
}

LifePic.hbm.xml

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<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.codeforgod.model">

	<class name="LifePic" table="t_lifePic">
		<id name="id" column="lifePicId">
			<generator class="native"></generator>
		</id>

		<property name="name" column="picName"></property>

		<many-to-one name="staff" column="staffId"
			class="cn.codeforgod.model.Staff">
		</many-to-one>

		<property name="note" column="note" type="string"></property>
	</class>

</hibernate-mapping>

WorkPic.hbm.xml

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<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.codeforgod.model">

	<class name="WorkPic" table="t_workPic">
		<id name="id" column="workPicId">
			<generator class="native"></generator>
		</id>

		<property name="name" column="picName"></property>

		<many-to-one name="staff" column="staffId"
			class="cn.codeforgod.model.Staff">
		</many-to-one>

		<property name="company" column="company" type="string"></property>
	</class>

</hibernate-mapping>

Staff.hbm.xml

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<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.codeforgod.model">

	<class name="Staff" table="t_staff">
		<id name="id" column="staffId">
			<generator class="native"></generator>
		</id>
		
		<property name="name" column="staffName"></property>
	</class>

</hibernate-mapping>

Hibernate.cfg.xml

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<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <!--数据库连接设置 -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql:///db_hibernate</property>
        <property name="connection.username">root</property>
        <property name="connection.password">123456</property>

       
        <!-- 方言 -->
        <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>
	
        <!-- 控制台显示SQL -->
        <property name="show_sql">true</property>

        <!-- 自动更新表结构 -->
        <property name="hbm2ddl.auto">update</property>
        
  		<mapping resource="cn/codeforgod/model/Staff.hbm.xml"/>
  		<mapping resource="cn/codeforgod/model/LifePic.hbm.xml"/>
  		<mapping resource="cn/codeforgod/model/WorkPic.hbm.xml"/>
  		
  		<mapping resource="cn/codeforgod/model/Staff2.hbm.xml"/>
  		<mapping resource="cn/codeforgod/model/Picture2.hbm.xml"/>
  		
  		<mapping resource="cn/codeforgod/model/Staff3.hbm.xml"/>
  		<mapping resource="cn/codeforgod/model/Picture3.hbm.xml"/>
  		
    </session-factory>

</hibernate-configuration>

Test.java

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package cn.codeforgod.test;


import java.io.IOException;
import java.text.ParseException;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;

import cn.codeforgod.model.LifePic;
import cn.codeforgod.model.LifePic2;
import cn.codeforgod.model.LifePic3;
import cn.codeforgod.model.Picture;
import cn.codeforgod.model.Picture2;
import cn.codeforgod.model.Picture3;
import cn.codeforgod.model.Staff;
import cn.codeforgod.model.Staff2;
import cn.codeforgod.model.Staff3;
import cn.codeforgod.model.WorkPic;
import cn.codeforgod.model.WorkPic2;
import cn.codeforgod.model.WorkPic3;
import cn.codeforgod.util.HibernateUtil;

public class Test
{
	public static void main(String[] args) throws ParseException, IOException
	{
		testType1();
//		testType2();
//		testType3();
	}

	public static void testType1()
	{
		SessionFactory sessionFactory = HibernateUtil.getSessionFactory();

		// 存
		Session session1 = sessionFactory.openSession();
		Transaction transaction1 = session1.beginTransaction();

		Staff staff = new Staff();
		staff.setName("Tom");

		Picture lifePic = new LifePic();
		lifePic.setName("life1.jpg");
		lifePic.setStaff(staff);
		((LifePic) lifePic).setNote("备注...");

		Picture workPic = new WorkPic();
		workPic.setName("work1.jpg");
		workPic.setStaff(staff);
		((WorkPic) workPic).setCompany("公司1");

		Set<Picture> pics = new HashSet<Picture>();
		pics.add(lifePic);
		pics.add(workPic);

		staff.setPics(pics);

		session1.save(lifePic);
		session1.save(workPic);
		session1.save(staff);

		transaction1.commit();
		session1.close();

		// 取
		Session session2 = sessionFactory.openSession();
		Transaction transaction2 = session2.beginTransaction();

		Staff staff2 = (Staff) session2.get(Staff.class, Integer.valueOf(1));
		@SuppressWarnings("unchecked")
		List<LifePic> lifePics = (List<LifePic>) session2
				.createQuery(
						"From LifePic l where l.staff.id=" + staff2.getId())
				.list();
		@SuppressWarnings("unchecked")
		List<WorkPic> workPics = (List<WorkPic>) session2
				.createQuery(
						"From WorkPic w where w.staff.id=" + staff2.getId())
				.list();
		Set<Picture> pics2 = new HashSet<Picture>();
		pics2.addAll(lifePics);
		pics2.addAll(workPics);
		System.out.println(staff2);
		for (Picture pic : pics2)
		{
			System.out.println(pic.getName());
		}

		transaction2.commit();
		session2.close();

		sessionFactory.close();
	}

	public static void testType2()
	{
		SessionFactory sessionFactory = HibernateUtil.getSessionFactory();

		// 存
		Session session1 = sessionFactory.openSession();
		Transaction transaction1 = session1.beginTransaction();

		Staff2 staff = new Staff2();
		staff.setName("Tom");

		Picture2 lifePic = new LifePic2();
		lifePic.setName("life1.jpg");
		lifePic.setStaff(staff);
		((LifePic2) lifePic).setNote("备注...");

		Picture2 workPic = new WorkPic2();
		workPic.setName("work1.jpg");
		workPic.setStaff(staff);
		((WorkPic2) workPic).setCompany("公司1");

		Set<Picture2> pics = new HashSet<Picture2>();
		pics.add(lifePic);
		pics.add(workPic);

		staff.setPics(pics);

		session1.save(staff);
		session1.save(lifePic);
		session1.save(workPic);

		transaction1.commit();
		session1.close();

		// 取
		Session session2 = sessionFactory.openSession();
		Transaction transaction2 = session2.beginTransaction();

		Staff2 staff2 = (Staff2) session2.get(Staff2.class, Integer.valueOf(1));
		Set<Picture2> pics2 = staff2.getPics();
		System.out.println(staff2);
		for (Picture2 pic : pics2)
		{
			System.out.println(pic.getName());
		}

		transaction2.commit();
		session2.close();

		sessionFactory.close();
	}

	public static void testType3()
	{
		SessionFactory sessionFactory = HibernateUtil.getSessionFactory();

		// 存
		Session session1 = sessionFactory.openSession();
		Transaction transaction1 = session1.beginTransaction();

		Staff3 staff = new Staff3();
		staff.setName("Tom");

		Picture3 lifePic = new LifePic3();
		lifePic.setName("life1.jpg");
		lifePic.setStaff(staff);
		((LifePic3) lifePic).setNote("备注...");

		Picture3 workPic = new WorkPic3();
		workPic.setName("work1.jpg");
		workPic.setStaff(staff);
		((WorkPic3) workPic).setCompany("公司1");

		Set<Picture3> pics = new HashSet<Picture3>();
		pics.add(lifePic);
		pics.add(workPic);

		staff.setPics(pics);

		session1.save(staff);
		session1.save(lifePic);
		session1.save(workPic);

		transaction1.commit();
		session1.close();

		// 取
		Session session2 = sessionFactory.openSession();
		Transaction transaction2 = session2.beginTransaction();

		Staff3 staff2 = (Staff3) session2.get(Staff3.class, Integer.valueOf(1));
		Set<Picture3> pics2 = staff2.getPics();
		System.out.println(staff2);
		for (Picture3 pic : pics2)
		{
			System.out.println(pic.getName());
		}

		transaction2.commit();
		session2.close();

		sessionFactory.close();
	}
}

数据库中表的关系如下图：

mappingExtend1

Type2：基类对应一个表

Demo：建立一个具体类Picture，并由两个子类LifePic和WorkPic继承该类，每个员工Staff有多个Picture。

Type2.mgc

类图关系如下：
2.mgc

Picture2.java

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package cn.codeforgod.model;

public class Picture2
{
	private long id;
	private String picType;
	private String name;
	private Staff2 staff;
	
	public String getPicType()
	{
		return picType;
	}
	public void setPicType(String picType)
	{
		this.picType = picType;
	}
	public long getId()
	{
		return id;
	}
	public void setId(long id)
	{
		this.id = id;
	}
	public String getName()
	{
		return name;
	}
	public void setName(String name)
	{
		this.name = name;
	}
	public Staff2 getStaff()
	{
		return staff;
	}
	public void setStaff(Staff2 staff)
	{
		this.staff = staff;
	}
	
}

LifePic2.java

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package cn.codeforgod.model;

public class LifePic2 extends Picture2
{
	private String note;	// 备注

	public String getNote()
	{
		return note;
	}

	public void setNote(String note)
	{
		this.note = note;
	}
	
	
}

WorkPic2.java

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package cn.codeforgod.model;

public class WorkPic2 extends Picture2
{
	private String company;	// 公司名称

	public String getCompany()
	{
		return company;
	}

	public void setCompany(String company)
	{
		this.company = company;
	}
}

Staff2.java

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package cn.codeforgod.model;

import java.util.Set;

public class Staff2
{
	private int id;
	private String name;
	private Set<Picture2> pics;
	
	public int getId()
	{
		return id;
	}
	public void setId(int id)
	{
		this.id = id;
	}
	public String getName()
	{
		return name;
	}
	public void setName(String name)
	{
		this.name = name;
	}
	public Set<Picture2> getPics()
	{
		return pics;
	}
	public void setPics(Set<Picture2> pics)
	{
		this.pics = pics;
	}
	@Override
	public String toString()
	{
		return "Staff [id=" + id + ", name=" + name + ", pics=" + pics + "]";
	}
	
}

Picture2.hbm.xml

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<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.codeforgod.model">

	<class name="Picture2" table="t_picture2">
		<id name="id" column="pictureId">
			<generator class="native"></generator>
		</id>

		<discriminator column="picType" type="string"></discriminator>

		<property name="name" column="picName"></property>

		<many-to-one name="staff" column="staffId"
			class="cn.codeforgod.model.Staff2">
		</many-to-one>
		
		<subclass name="cn.codeforgod.model.LifePic2" discriminator-value="lifePic">
			<property name="note" type="string"></property>
		</subclass>
		
		<subclass name="cn.codeforgod.model.WorkPic2" discriminator-value="workPic">
			<property name="company" type="string"></property>
		</subclass>
	</class>

</hibernate-mapping>

Staff2.hbm.xml

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<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.codeforgod.model">

	<class name="Staff2" table="t_staff2">
		<id name="id" column="staffId">
			<generator class="native"></generator>
		</id>
		
		<property name="name" column="staffName"></property>
		
		<set name="pics">
			<key column="staffId"></key>
			<one-to-many class="cn.codeforgod.model.Picture2" />
		</set>
	</class>

</hibernate-mapping>

数据库中表的关系如下图：

mappingExtend2

Type3：每个类对应一个表

Demo：建立一个具体类Picture，并由两个子类LifePic和WorkPic继承该类，每个员工Staff有多个Picture。

Type3.mgc

类图关系如下：
3.mgc

Picture3.java

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package cn.codeforgod.model;

public class Picture3
{
	private long id;
	private String picType;
	private String name;
	private Staff3 staff;
	
	public String getPicType()
	{
		return picType;
	}
	public void setPicType(String picType)
	{
		this.picType = picType;
	}
	public long getId()
	{
		return id;
	}
	public void setId(long id)
	{
		this.id = id;
	}
	public String getName()
	{
		return name;
	}
	public void setName(String name)
	{
		this.name = name;
	}
	public Staff3 getStaff()
	{
		return staff;
	}
	public void setStaff(Staff3 staff)
	{
		this.staff = staff;
	}	
}

LifePic3.java

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package cn.codeforgod.model;

public class LifePic3 extends Picture3
{
	private String note;	// 备注

	public String getNote()
	{
		return note;
	}

	public void setNote(String note)
	{
		this.note = note;
	}
	
	
}

WorkPic3.java

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package cn.codeforgod.model;

public class WorkPic3 extends Picture3
{
	private String company;	// 公司名称

	public String getCompany()
	{
		return company;
	}

	public void setCompany(String company)
	{
		this.company = company;
	}
}

Staff3.java

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package cn.codeforgod.model;

import java.util.Set;

public class Staff3
{
	private int id;
	private String name;
	private Set<Picture3> pics;
	
	public int getId()
	{
		return id;
	}
	public void setId(int id)
	{
		this.id = id;
	}
	public String getName()
	{
		return name;
	}
	public void setName(String name)
	{
		this.name = name;
	}
	public Set<Picture3> getPics()
	{
		return pics;
	}
	public void setPics(Set<Picture3> pics)
	{
		this.pics = pics;
	}
	@Override
	public String toString()
	{
		return "Staff [id=" + id + ", name=" + name + ", pics=" + pics + "]";
	}
	
}

Picture3.hbm.xml

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<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.codeforgod.model">

	<class name="Picture3" table="t_picture3">
		<id name="id" column="pictureId">
			<generator class="native"></generator>
		</id>

		<property name="name" column="picName"></property>

		<many-to-one name="staff" column="staffId"
			class="cn.codeforgod.model.Staff3">
		</many-to-one>

		<joined-subclass name="cn.codeforgod.model.LifePic3"
			table="t_lifePic3">
			<key column="lifePicId"></key>
			<property name="note" column="note" type="string"></property>
		</joined-subclass>

		<joined-subclass name="cn.codeforgod.model.WorkPic3"
			table="t_workPic3">
			<key column="workPicId"></key>
			<property name="company" column="company" type="string"></property>
		</joined-subclass>
	</class>

</hibernate-mapping>

Staff3.hbm.xml

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<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.codeforgod.model">

	<class name="Staff3" table="t_staff3">
		<id name="id" column="staffId">
			<generator class="native"></generator>
		</id>
		
		<property name="name" column="staffName"></property>
		
		<set name="pics">
			<key column="staffId"></key>
			<one-to-many class="cn.codeforgod.model.Picture3" />
		</set>
	</class>

</hibernate-mapping>

数据库中表的关系如下图：

mappingExtend3

Tips

在映射文件中，不能有cascade属性。

然后本文好似有点难以理解，但是这是Hibernate给我们的思想，值得深思。愿你我都能写出漂亮的代码，让中国的IT也可以让世界瞩目（虽然这几乎不可能实现）。

坚持原创技术分享，您的支持将鼓励我继续创作