Hibernate Study

Hibernate can be configured by creating a property file named hibernate.properties in the src directory and adding its path to the application's classpath. This file consists of the properties used by Hibernate to connect to database, generate schema, and obtain other database-specific information. To reflect changes in the underlying database into the whole application, only values of the properties in this file need to be modified. Listing 1 shows a simple example. Most of these properties are self-explanatory.

Listing 1: A simplel example of hibernate.properties file

hibernate.connection.driver_class = COM.ibm.db2.jdbc.app.DB2Driver
hibernate.connection.url = jdbc:db2:inventory
hibernate.connection.username = db2admin
hibernate.connection.password = rafel
hibernate.dialect = cirrus.hibernate.sql.DB2Dialect

Listing 2: Example of  a simple hibernate.cfg.xml
 
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 2.0//EN"
 "http://hibernate.sourceforge.net/hibernate-configuration-2.0.dtd">

<hibernate-configuration>

    <session-factory>
        <property name="hibernate.connection.driver_class">COM.ibm.db2.jdbc.app.DB2Driver</property>
        <property name="hibernate.connection.url">jdbc:db2:empl</property>
        <property name="hibernate.connection.username">db2admin</property>
        <property name="hibernate.connection.password">rafel</property>
        <property name="dialect">cirrus.hibernate.sql.DB2Dialect</property>
     

        <mapping resource="com/myPackage/myApplication/data/Event.hbm.xml"/>

    </session-factory>

</hibernate-configuration>

Listing 3 : An example of mapping document Event.hbm.xml


<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

        <class name="com.myPackage.myApplication.Event" table="EVENTS">
                <id name="id" column="uid" type="long">
                        <generator class="increment"/>
                </id>
                <property name="date" column="event_date" type="timestamp"/>
                <property name="title" column="event_title" type="string"/>
        </class>

</hibernate-mapping>

Listing 4 Stub Classes

package com.myPackage.myApplication;

public class Event {
    private String title;
    private Date date;
    private Long id;

    Event(){ }

    public Long getId() {
        return id;
    }

    private void setId(Long id) {
        this.id = id;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }
}

Listing 5: A simple class for initializing Hibernate and making objects persistent.

package com.myPackage.myApplication;

import net.sf.hibernate.SessionFactory;
import net.sf.hibernate.HibernateException;
import net.sf.hibernate.Transaction;
import net.sf.hibernate.cfg.Configuration;

public class EventManager {

  public static void main(String[] args) {
	
        // Instantiate and populate object to be persisted
        Event ev = new Event();
        ev.setDate("1/4/2004")
        ev.setTitle("Hibernate startup");

 
        try {
           //Start Hibernate
        Configuration cfg = new Configuration().addClass(Event.class);
        SessionFactory sf = cfg.buildSessionFactory();

        //Open Session
        Session sess = sf.openSession();

        } catch (HibernateException e) {
            e.printStackTrace();
        }

        //Save Product and close Session
        Transaction t = sess.beginTransaction();
        sess.save(ev);
        t.commit();
        sess.close();
   
    }

}