20.14. Obtaining an EntityMangerFactory

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`hibernate-osgi` registers an OSGi service, using the JPA `PersistenceProvider` interface name, that bootstraps and creates an `EntityManagerFactory` specific for OSGi environments.

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It is VITAL that your `EntityManagerFactory` be obtained through the service, rather than creating it manually.
The service handles the OSGi `ClassLoader`, discovered extension points, scanning, etc.
Manually creating an `EntityManagerFactory` is guaranteed to NOT work during runtime!

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<div class="title">Example 493. Discover/Use `EntityManagerFactory`</div>
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<pre class="prettyprint highlight">`public class HibernateUtil {

    private EntityManagerFactory emf;

    public EntityManager getEntityManager() {
        return getEntityManagerFactory().createEntityManager();
    }

    private EntityManagerFactory getEntityManagerFactory() {
        if ( emf == null ) {
            Bundle thisBundle = FrameworkUtil.getBundle( HibernateUtil.class );
            BundleContext context = thisBundle.getBundleContext();

            ServiceReference serviceReference = context.getServiceReference( PersistenceProvider.class.getName() );
            PersistenceProvider persistenceProvider = ( PersistenceProvider ) context.getService( serviceReference );

            emf = persistenceProvider.createEntityManagerFactory( "YourPersistenceUnitName", null );
        }
        return emf;
    }
}`</pre>
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