Hibernate: HQL in Depth

Hibernate: HQL in Depth - HQL in the Real World
(Page 3 of 4 )

Until now I was doing all the setting up and configuration in the main(). This time I will be creating a class with a reusable and (almost) generic function. The setting up of the Hibernate will happen in the constructor. So let's begin.

First, the usual: package name and imports:

package com.someorg.persist.op;

import java.util.List;

import org.hibernate.Hibernate;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import com.someorg.persist.Order

Then the class declaration:

public class OrderOP {
:
:
}

Now comes the constructor and the configurations:

public class OrderOP {

SessionFactory sf;

    public OrderOP(){
            Configuration cfg = new Configuration()
                    .addClass(Order.class);

            sf = cfg.buildSessionFactory();

    }
:
:
}

The next function retrieves the data(Orders and Product) on the basis of the upper and lower priceTotals passed as arguments.

public class OrderOP {

SessionFactory sf;

    public OrderOP(){
        Configuration cfg = new Configuration()
            .addClass(Order.class);

        sf = cfg.buildSessionFactory();

     }

     public Order getOrder(String lower, String upper){
         // open session
            Session sess = sf.openSession();
            String query = "select o from o "
                + "Order as o join o.products as p "
                + "where o.priceTotal > :priceTotalLower
" 
                + "and o.priceTotal
< :priceTotalUpper";           

            Query q = sess.createQuery(query);
            q.setDouble("priceTotalLower", 
                    Double.parseDouble(lower));

            q.setDouble("priceTotalUpper", 
                    Double.parseDouble(upper));

            List list = q.list();

           Order o=(Order)list.iterator.next();

           return o;

           }

:
:
}

And last but not least, the main function for testing:

public class OrderOP {

SessionFactory sf;

    public OrderOP(){
        Configuration cfg = new Configuration()
             .addClass(Order.class);

        sf = cfg.buildSessionFactory();

    }

    public Order getOrder(String lower, String upper){
        // open session
       Session sess = sf.openSession();
       String query = "select o from o "
            + "Order as o join o.products as p "
            + "where o.priceTotal > :priceTotalLower "
            + "and o.priceTotal < :priceTotalUpper";         

       Query q = sess.createQuery(query);
       q.setDouble("priceTotalLower", 
            Double.parseDouble(lower));

       q.setDouble("priceTotalUpper", 
            Double.parseDouble(upper));

        List list = q.list();

        Order o=(Order)list.iterator.next();

        return o;

   }

   public static void main(String args[]){
        Order o=OrderOP().getOrder
(“2000’,”3000”);                  

        System.out.println(“Order Id:”+ o.id);
        //and so on

    }

}

That’s it. Such a class can be used as a data processing layer’s component. In the future I will be adding more functionalities to it.

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