Hibernate Table Per Class Inheritance Hierarchy Example Using XML

Tools and Technologies we are using here:

JDK 7
Hibernate 4.3.7
MySql 5.1.10
Eclipse Juno 4.2

Main Objects of this project are:

jar files
hibernate.cfg.xml
*.hbm.xml(mapping files)
database

Step 1. Create database script.

CREATE DATABASE `hibernate_tutorial` ;

USE `hibernate_tutorial`;

/*Table structure for table `payment` */

DROP TABLE IF EXISTS `payment`;

CREATE TABLE `payment` (
  `payment_id` bigint(20) NOT NULL AUTO_INCREMENT,
  `payment_mode` varchar(255) NOT NULL,
  `amount` float DEFAULT NULL,
  `order_number` varchar(255) DEFAULT NULL,
  `payment_date` datetime DEFAULT NULL,
  `card_type` varchar(255) DEFAULT NULL,
  `bank` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`payment_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1;

Step 2. Create a Java Project
Go to File Menu then New->Java Project, and provide the name of the project.

Create a lib folder(Optional):
Right click on your project and create a new folder named it as lib,this step is optional this is just to place all the required jar file. You may put all the jar files anywhere in your system's location, In this project we have placed all the required jar files in lib folder.

Step 3. Add libraries(jar files) into project's build path:
required jar files:

antlr-2.7.7.jar
dom4j-1.6.1.jar
hibernate-commons-annotations-4.0.5.Final.jar
hibernate-core-4.3.7.Final.jar
hibernate-jpa-2.1-api-1.0.0.Final.jar
jandex-1.1.0.Final.jar
javassist-3.18.1-GA.jar
jboss-logging-3.1.3.GA.jar
jboss-logging-annotations-1.2.0.Beta1.jar
jboss-transaction-api_1.2_spec-1.0.0.Final.jar
mysql-connector-java-5.1.3-rc-bin.jar

Step 4. Create a hibernate.cfg.xml file: Here we placed hibernate.cfg.xml file inside com.javamakeuse.hbm.inheritance.xmls package.

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">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/hibernate_tutorial</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>
         
        <property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
 
        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>
        <property name="hbm2ddl.auto">update</property>
        <mapping resource="com/javamakeuse/hbm/inheritance/xmls/Payment.hbm.xml"/>
          
    </session-factory>
</hibernate-configuration>

Step 5. Create Payment.hbm.xml mapping file: Here we placed all the xml files inside com.javamakeuse.hbm.inheritance.xmls package.

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 package="com.javamakeuse.hbm.inheritance.pojo">
 <class name="Payment" table="payment">
  <id name="paymentID" type="java.lang.Long">
   <column name="payment_id" />
   <generator class="identity" />
  </id>
  <discriminator column="payment_mode" type="string"/>
  <property name="amount" column="amount" type="float" />
  <property name="orderNumber" column="order_number" type="string" />
  <property name="paymentDate" column="payment_date" type="java.util.Date" />
  
  <subclass name="CashPayment" extends="Payment"
   discriminator-value="Cash">
  </subclass>
  <subclass name="CardPayment" extends="Payment"
   discriminator-value="Card">
   <property name="cardType" column="card_type" type="string" />
  </subclass>
  <subclass name="ChequePayment" extends="Payment"
   discriminator-value="Cheque">
   <property name="bank" column="bank" type="string" />
  </subclass>
 </class>
</hibernate-mapping>

Note: The discriminator column contains marker values that tell the persistence layer what subclass to instantiate for a particular row.

Step 6: Create Payment.java pojo class: It contains all the properties defined inside the Payment.hbm.xml mapping file.

Payment.java

package com.javamakeuse.hbm.inheritance.pojo;

import java.util.Date;

public class Payment {

 private float amount;
 private String orderNumber;
 private Date paymentDate;
 private long paymentID;

 public long getPaymentID() {
  return paymentID;
 }

 public void setPaymentID(long paymentID) {
  this.paymentID = paymentID;
 }

 public float getAmount() {
  return amount;
 }

 public void setAmount(float amount) {
  this.amount = amount;
 }

 public String getOrderNumber() {
  return orderNumber;
 }

 public void setOrderNumber(String orderNumber) {
  this.orderNumber = orderNumber;
 }

 public Date getPaymentDate() {
  return paymentDate;
 }

 public void setPaymentDate(Date paymentDate) {
  this.paymentDate = paymentDate;
 }

 @Override
 public String toString() {
  return "Payment [amount=" + amount + ", orderNumber=" + orderNumber
    + ", paymentDate=" + paymentDate + "]";
 }

}

Step 7: Now create CardPayment.java sub class

package com.javamakeuse.hbm.inheritance.pojo;

public class CardPayment extends Payment {
 private String cardType;

 public String getCardType() {
  return cardType;
 }

 public void setCardType(String cardType) {
  this.cardType = cardType;
 }

 @Override
 public String toString() {
  return "CardPayment [cardType=" + cardType + "]";
 }

}

Step 8: Create another sub class ChequePayment.java

package com.javamakeuse.hbm.inheritance.pojo;

public class ChequePayment extends Payment {
 private String bank;

 public String getBank() {
  return bank;
 }

 public void setBank(String bank) {
  this.bank = bank;
 }

 @Override
 public String toString() {
  return "ChequePayment [bank=" + bank + "]";
 }

}

Step 9: Create another sub class CashPayment.java

package com.javamakeuse.hbm.inheritance.pojo;

public class CashPayment extends Payment{

}

Step 10: Create HibernateUtility.java class to build sessionFactory via loading configuration file.

package com.javamakeuse.hbm.inheritance.utils;


import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;

public class HibernateUtility {
 private static final SessionFactory sessionFactory = buildSessionFactory();

 private static SessionFactory buildSessionFactory() {
  Configuration configuration = new Configuration();
  configuration.configure("/com/javamakeuse/hbm/inheritance/xmls/hibernate.cfg.xml");

  ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
    .applySettings(configuration.getProperties()).build();
  SessionFactory sessionFactory = configuration
    .buildSessionFactory(serviceRegistry);
  return sessionFactory;
 }

 public static SessionFactory getSessionFactory() {
  return sessionFactory;
 }
}

Step 11: Create PaymentDAO.java class to perform the CRUD operations

package com.javamakeuse.hbm.inheritance.dao;

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

import com.javamakeuse.hbm.inheritance.pojo.Payment;
import com.javamakeuse.hbm.inheritance.utils.HibernateUtility;

public class PaymentDAO {
 static SessionFactory sessionFactory;
 static {
  sessionFactory = HibernateUtility.getSessionFactory();
 }

 public static Payment save(Payment payment) {
  Session session = sessionFactory.openSession();

  session.beginTransaction();

  session.save(payment);

  session.getTransaction().commit();

  return payment;
 }

 public static Payment update(Payment payment) {
  Session session = sessionFactory.openSession();

  session.beginTransaction();

  session.merge(payment);

  session.getTransaction().commit();

  return payment;

 }

 public static void delete(Payment payment) {
  Session session = sessionFactory.openSession();

  session.beginTransaction();

  session.delete(payment);

  session.getTransaction().commit();

 }

}

Step 12: Create one more DAO class CardPaymentDAO.java class to fetch the sub class data.

package com.javamakeuse.hbm.inheritance.dao;

import java.util.List;

import org.hibernate.Session;
import org.hibernate.criterion.Restrictions;

import com.javamakeuse.hbm.inheritance.pojo.CardPayment;
import com.javamakeuse.hbm.inheritance.pojo.Payment;

public class CardPaymentDAO extends PaymentDAO {

 @SuppressWarnings("unchecked")
 public static CardPayment findById(long id) {
  Session session = sessionFactory.openSession();
  List<CardPayment> cardPayment = session.createCriteria(Payment.class)
    .add(Restrictions.eq("class", "Card")).list();

  return cardPayment.get(0);
 }
}

Step 13: Create PaymentService.java class to call the methods of DAO class.

package com.javamakeuse.hbm.inheritance.service;

import java.text.SimpleDateFormat;

import com.javamakeuse.hbm.inheritance.dao.CardPaymentDAO;
import com.javamakeuse.hbm.inheritance.dao.PaymentDAO;
import com.javamakeuse.hbm.inheritance.pojo.CardPayment;

public class PaymentService {
 public static void main(String[] args) {
  try {
   SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
   CardPayment payment = new CardPayment();
   payment.setCardType("Debit");
   payment.setAmount(250);
   payment.setOrderNumber("WO0001");
   payment.setPaymentDate(sdf.parse("2015-01-01"));
   PaymentDAO.save(payment);

   // Fetching cardPayment from the database.
   System.out.println(CardPaymentDAO.findById(payment.getPaymentID()));
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
}

Run the PaymentService.java class it will create a row inside the payment table with payment_mode value as Card

OUT PUT:

Hibernate: 
    insert 
    into
        payment
        (amount, order_number, payment_date, card_type, payment_mode) 
    values
        (?, ?, ?, ?, 'Card')
Hibernate: 
    select
        this_.payment_id as payment_1_0_0_,
        this_.amount as amount3_0_0_,
        this_.order_number as order_nu4_0_0_,
        this_.payment_date as payment_5_0_0_,
        this_.card_type as card_typ6_0_0_,
        this_.bank as bank7_0_0_,
        this_.payment_mode as payment_2_0_0_ 
    from
        payment this_ 
    where
        this_.payment_mode=?
CardPayment [cardType=Debit]

That's it

Download the complete example from here Source Code

References
Reference 1
Reference 2

Hibernate Table Per Class Inheritance Hierarchy Example Using XML

Tools and Technologies we are using here:

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