Hibernate Association and join

hi, can u please tell me SQL DDL queries to create Product and Dealer table... and also tell me java code for Product and Dealer bean...

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March 17, 2011 at 3:17 PM

Exmple of Hibernate Associations and Joins using Javadb / derby database

HibernateUtil.java file

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateUtil {

    public static final SessionFactory sessionFactory;

    static {
        try {
            // Create the SessionFactory from hibernate.cfg.xml
            sessionFactory = new Configuration().configure().buildSessionFactory();
        } catch (Throwable ex) {
            // Make sure you log the exception, as it might be swallowed
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static final ThreadLocal session = new ThreadLocal();

    public static Session currentSession() throws HibernateException {
        Session s = (Session) session.get();
        // Open a new Session, if this thread has none yet
        if (s == null) {
            s = sessionFactory.openSession();
            // Store it in the ThreadLocal variable
            session.set(s);
        }
        return s;
    }

    public static void closeSession() throws HibernateException {
        Session s = (Session) session.get();
        if (s != null)
            s.close();
        session.set(null);
    }
}

Main.java File

import java.util.*;


import org.hibernate.*;


public class Main {

    public static void main(String[] args) {
        Session session = HibernateUtil.currentSession();

            String hql = "from Product p inner join p.supplier as s";
            Query query = session.createQuery(hql);
            List results = query.list();
        displayObjectsList(results);



    }
    static public void displayObjectsList(List list)
    {
        Iterator iter = list.iterator();
        if (!iter.hasNext())
        {
            System.out.println("No objects to display.");
            return;
        }
        while (iter.hasNext())
        {
            System.out.println("---------New object-------------");
            Object[] obj = (Object[]) iter.next();

                Product p = (Product)obj[0];
                Supplier s = (Supplier)obj[1];

                System.out.println("Product ID :"+p.getId());
                System.out.println("Product Name :"+p.getName());
                System.out.println("Product Price :"+p.getPrice());
                System.out.println("Supplier ID:"+s.getId());
                System.out.println("Supplier Name :"+s.getName());
        }
    }       
}

Product.java

public class Product
{
    private int id;
    private Supplier supplier;

    private String name;

    private double price;

    public Product()
    {
        super();
    }

    public Product(String name, double price)
    {
        super();
        this.name = name;

        this.price = price;
    }


    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 Supplier getSupplier()
    {
        return supplier;
    }
    public void setSupplier(Supplier supplier)
    {
        this.supplier = supplier;
    }

    public double getPrice()
    {
        return price;
    }
    public void setPrice(double price)
    {
        this.price = price;
    }
}

Supplier.java

import java.util.ArrayList;
import java.util.List;

public class Supplier
{
    private int id;
    private String name;
    private List products = new ArrayList();

    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 List getProducts()
    {
        return products;
    }
    public void setProducts(List products)
    {
        this.products = products;
    }
}

Hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <!-- Database connection settings -->
         <property name="hibernate.connection.driver_class">org.apache.derby.jdbc.EmbeddedDriver</property>
      <property name="hibernate.connection.url">jdbc:derby://localhost:1527/sample;create=true;autocommit=true</property>
      <property name="hibernate.connection.username">NarendraMah</property>
      <property name="hibernate.connection.schema">APP</property>
      <property name="hibernate.connection.password">NarendraMah</property>
      <property name="hibernate.connection.pool_size">10</property>
      <property name="hibernate.connection.autommit">true</property>
      <property name="show_sql">true</property>

      <property name="dialect">org.hibernate.dialect.DerbyDialect</property>
      <property name="hibernate.hbm2ddl.auto">update</property>

        <!-- Mapping files -->
        <mapping resource="Product.hbm.xml"/>
        <mapping resource="Supplier.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

Product.xml

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

<hibernate-mapping>
   <class name="Product" table="APP.PRODUCT">
      <id name="id" type="int" column="ID">
         <generator class="increment"/>
      </id>

      <property name="name" type="string" column="NAME"/>

      <property name="price" type="double" column="PRICE"/>
      <many-to-one name="supplier" class="Supplier" column="SUPPLIERID"/>

   </class>

   <query name="HQLpricing"><![CDATA[
       select product.price from Product product where product.price > 25.0]]>
    </query>   
   <sql-query name="SQLpricing">
      <return-scalar column="price" type="double"/>
      <![CDATA[
       select product.price from Product as product where product.price > 25.0]]>
   </sql-query>     
</hibernate-mapping>

Supplier.hbm.xml

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

<hibernate-mapping>
   <class name="Supplier" table="APP.SUPPLIER">
      <id name="id" type="int" column="ID">
         <generator class="increment"/>
      </id>

      <property name="name" type="string" column="NAME"/>
      <bag name="products" inverse="true" cascade="all,delete-orphan">
        <key column="supplierId"/>
        <one-to-many class="Product"/>
      </bag>


   </class>
</hibernate-mapping>

SQL Queries

create table APP.SUPPLIER
(
    ID  INTEGER NOT NULL 
        PRIMARY KEY,
    NAME  VARCHAR(20) NOT NULL  

 ); 
 create table APP.PRODUCT
(
    ID  INTEGER NOT NULL 
        PRIMARY KEY,
    NAME  VARCHAR(20) NOT NULL , 
    PRICE DOUBLE NOT NULL,
    SUPPLIERID integer not null
 );
  insert into APP.SUPPLIER values(1,'One Services');
 insert into APP.SUPPLIER values(2,'XLS Services');
 insert into APP.SUPPLIER values(3,'Infocom Services');

 insert into APP.PRODUCT values(1,'Hard Disk',2000.00,1);
 insert into APP.PRODUCT values(2,'CD',100.00,2);
 insert into APP.PRODUCT values(3,'Processor',10000.00,3);
 insert into APP.PRODUCT values(4,'Cable',150.00,1);
 insert into APP.PRODUCT values(5,'USB Drive',800.00,2);
 insert into APP.PRODUCT values(6,'Mouse',200.00,3);

March 17, 2011 at 3:18 PM

Exmple of Associations and Joins using Javadb / derby database