Simple Hibernate Example with Transient (Non-Persistent) Data

[Christopher Rygaard]

This is the simplest stand-alone example of a Hibernate persistent object that contains non-persistent (transient) data.

This is very similar to my POJO example. The only substantive difference is the MyPersistentObject class now has an instance variable annotated with @Transient. That instance variable will not be written to persistence when the object is written.

Here is the persistent class with a transient field:

@javax.persistence.Entity
public class MyPersistentObject
{
   @javax.persistence.Id
   @javax.persistence.GeneratedValue( generator = "increment" )
   @org.hibernate.annotations.GenericGenerator( name = "increment", strategy = "increment" )
   private Long    _persistenceID;
   private String  _title;
   @javax.persistence.Transient
   private String  _data;

   // Hibernate needs a no-argument constructor
   private MyPersistentObject()
   {
   }

   // for application use, to create new persistent objects
   public MyPersistentObject( String title,
                              String data )
   {
      _title = title;
      _data = data;
   }

   public void display()
   {
      System.out.println( "* Title = " + _title );
      System.out.println( "   Data = " + _data );
      System.out.println( "     ID = " + _persistenceID );
   }
}

This is an example of how to use the persistent class:

public class HibernateExample
{
   private org.hibernate.SessionFactory _sessionFactory;
   private MyPersistentObject           _myPersistentObject1;
   private MyPersistentObject           _myPersistentObject2;
   private MyPersistentObject           _myPersistentObject3;

   final static public void main( String arguments[] )
   {
      HibernateExample example;
      example = new HibernateExample();
      example.createPersistentObjects();
      example.readAndDisplayPersistentObjects();
      example.manipulatePersistentObjects();
      example.readAndDisplayPersistentObjects();
      example.cleanup();
   }

   private HibernateExample()
   {
      org.hibernate.cfg.Configuration configuration;

      java.util.logging.Logger.getLogger( "org.hibernate" ).setLevel( java.util.logging.Level.SEVERE );  // Supress Hibernate's excessive output

      configuration = new org.hibernate.cfg.Configuration();
      configuration.setProperty( "hibernate.dialect",                 "org.hibernate.dialect.H2Dialect" );                                          // Customize this for your particular RDBMS
      configuration.setProperty( "hibernate.connection.driver_class", "org.h2.Driver" );                                                            // Customize this for your particular RDBMS
      configuration.setProperty( "hibernate.connection.url",          "jdbc:h2:file:C:/SFTData/SFTDatabases/SFTInterfaceData;DB_CLOSE_DELAY=-1" );  // Customize this for your particular RDBMS
      configuration.setProperty( "hibernate.connection.username",     "sa" );                                                                       // Customize this for your particular RDBMS
      configuration.setProperty( "hibernate.connection.password",     "" );     // Customize this for your particular RDBMS installation
      configuration.setProperty( "hibernate.connection.pool_size",    "1" );    // Customize this for your particular RDBMS installation
      configuration.setProperty( "hibernate.cache.provider_class",    "org.hibernate.cache.internal.NoCacheProvider" );  // This is not ready for prime-time
      configuration.setProperty( "hibernate.show_sql",                "false" );  // Tell hibernate to not echo the SQL
      configuration.setProperty( "hibernate.hbm2ddl.auto",            "create" );
      configuration.addAnnotatedClass( MyPersistentObject.class );

      _sessionFactory = configuration.buildSessionFactory();
   }

   final private void createPersistentObjects()
   {
      org.hibernate.Session     session;
      boolean                   committed;
      org.hibernate.Transaction transaction;

      session = _sessionFactory.openSession();

      try
      {
         committed = false;
         transaction = session.beginTransaction();

         try
         {
            _myPersistentObject1 = new MyPersistentObject( "First persistent object", "transient data 1" );
            session.save( _myPersistentObject1 );

            _myPersistentObject2 = new MyPersistentObject( "A second persistent object", "transient data 2" );
            session.save( _myPersistentObject2 );

            transaction.commit();
            committed = true;
         }
         finally
         {
            if ( !committed )
            {
               transaction.rollback();
            }
         }
      }
      finally
      {
         session.close();
      }
   }

   final private void manipulatePersistentObjects()
   {
      org.hibernate.Session     session;
      org.hibernate.Transaction transaction;

      session = _sessionFactory.openSession();

      try
      {
         transaction = session.beginTransaction();

         _myPersistentObject3 = new MyPersistentObject( "A third persistent object", "transient data 3" );
         session.save( _myPersistentObject3 );

         session.delete( _myPersistentObject2 );

         transaction.commit();
      }
      finally
      {
         session.close();
      }
   }

   final private void readAndDisplayPersistentObjects()
   {
      org.hibernate.Session session;
      java.util.List<MyPersistentObject> result;

      session = _sessionFactory.openSession();

      try
      {
         session.beginTransaction();

         result = (java.util.List<MyPersistentObject>)( session.createQuery("from MyPersistentObject").list() );

         System.out.println( "List:" );
         for ( MyPersistentObject persistentObject: result )
         {
            persistentObject.display();
         }

         session.getTransaction().commit();
      }
      finally
      {
         session.close();
      }
   }

   final private void cleanup()
   {
      if ( _sessionFactory != null )
      {
         _sessionFactory.close();
      }
   }
}