Hibernate Inheritance: Table Per Concrete Class Hierarchy

Something like previous example but the changes are at mapping file only, and one more thing is..

x number of derived classes = x number of tables in the database

• Once we save the derived class object, then derived class data and base class data will be saved in the derived class related table in the database
• for this type we need the tables for derived classes, but not for the base class
• in the mapping file we need to use one new element <union-subclass — >under <class —>

Required files_

• Payment.java (Base class)
• CreditCard.java (Derived class)
• Cheque.java (Derived class)
• ClientForSave.java (for our logic)
• Payment.hbm.xml
• hibernate.cfg.xml

Payment.java:

package str;

public class Payment{

	private int paymentId;
	private double amount;

	public int getPaymentId() {
		return paymentId;
	}
	public void setPaymentId(int paymentId) {
		this.paymentId = paymentId;
	}
	public double getAmount() {
		return amount;
	}
	public void setAmount(double amount) {
		this.amount = amount;
	}	 

}

CreditCard.java:

package str;

public class CreditCard extends Payment{

	private String CreditCardType;

	public String getCreditCardType() {
		return CreditCardType;
	}

	public void setCreditCardType(String creditCardType) {
		CreditCardType = creditCardType;
	}

}

Cheque.java:

package str;

public class Cheque extends Payment{

	private String ChequeType;

	public String getChequeType() {
		return ChequeType;
	}

	public void setChequeType(String chequeType) {
		ChequeType = chequeType;
	}

}

ClientForSave.java

package str;

import org.hibernate.*;
import org.hibernate.cfg.*;
 
public class ClientForSave { 
 
    public static void main(String[] args)
    {
 
        Configuration cfg = new Configuration();
        cfg.configure("hibernate.cfg.xml"); 
 
        SessionFactory factory = cfg.buildSessionFactory();
        Session session = factory.openSession();

        CreditCard c=new CreditCard();
 
        c.setPaymentId(10);
        c.setAmount(2500);
        c.setCreditCardType("Visa");

 
        
        Cheque c1=new Cheque();
        
        c1.setPaymentId(11);
        c1.setAmount(2600);
        c1.setChequeType("ICICI");

        
        
        Transaction tx = session.beginTransaction();
        session.save(c);
        session.save(c1);
        System.out.println("Object saved successfully.....!!");
        tx.commit();
        session.close();
        factory.close();
    }
 
}

Payment.hbm.xml:

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

<hibernate-mapping>

<class name="str.Payment" table="PAYMENT">

<id name="paymentId" column="pid" />
<property name="amount" column="amt" />

<union-subclass name="str.CreditCard">
<property name="CreditCardType" column="cctype" length="10" />
</union-subclass>

<union-subclass name="str.Cheque">
<property name="ChequeType" column="cqtype" length="10" />
</union-subclass>

</class>
</hibernate-mapping>

hibernate.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="connection.driver_class">oracle.jdbc.driver.OracleDriver
</property>
<property name="connection.url">jdbc:oracle:thin:@www.java4s.com:1521:XE</property>
<property name="connection.username">system</property>
<property name="connection.password">admin</property>

<property name="dialect">org.hibernate.dialect.OracleDialect</property>
<property name="show_sql">true</property>
<property name="hbm2ddl.auto">update</property>

<mapping resource="Payment.hbm.xml" />

</session-factory>
</hibernate-configuration>

Eclipse Output

In the database

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::. About the Author .::
		Sivateja Kandula - Java/J2EE Full Stack Developer Founder of Java4s - Get It Yourself, A popular Java/J2EE Programming Blog, Love Java and UI frameworks. You can sign-up for the Email Newsletter for your daily dose of Java tutorials.