src/javax/persistence/osgi/ProviderTrackerCustomizer.java

/*******************************************************************************
 * Copyright (c) 1998, 2009 Oracle. All rights reserved. 
 * 
 * This program and the accompanying materials are made available under the 
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0 
 * which accompanies this distribution. 
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at 
 * http://www.eclipse.org/org/documents/edl-v10.php.
 * 
 * Contributors:
 *     tware,mkeith - Initial OSGi support for JPA 
 *
 ******************************************************************************/
package javax.persistence.osgi;

import javax.persistence.Persistence;
import javax.persistence.spi.PersistenceProvider;

import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.util.tracker.ServiceTrackerCustomizer;

public class ProviderTrackerCustomizer implements ServiceTrackerCustomizer {

	public static final String PERSISTENCE_PROVIDER = "javax.persistence.spi.PersistenceProvider";

	private BundleContext ctx;

	public ProviderTrackerCustomizer(BundleContext context) {
		this.ctx = context;
	}

	// -------------------------------------------------------------
	// Service was added
	// -------------------------------------------------------------
	public Object addingService(ServiceReference reference) {
		log("New service detected...");

		String providerName = getProviderName(reference);
		PersistenceProvider provider = (PersistenceProvider) ctx.getService(reference);
		Persistence.addProvider(provider);

		log("Added service " + providerName);
		return provider;
	}

	// -------------------------------------------------------------
	// Service was modified
	// -------------------------------------------------------------
	public void modifiedService(ServiceReference reference, Object serviceObject) {
		// Rogue provider -- we don't support modifying provider services
		this.removedService(reference, serviceObject);
	}

	// -------------------------------------------------------------
	// Service was removed
	// -------------------------------------------------------------
	public void removedService(ServiceReference reference, Object serviceObject) {
		log("Removing service...");

		String providerName = getProviderName(reference);
		Persistence.removeProvider(providerName);

		log("Removed service " + providerName + " service object: " + serviceObject);
	}

	// -------------------------------------------------------------
	// Helper method to get provider name from the service reference.
	// Assumes that provider services are registered with property
	// that indicates the name of the provider impl class.
	// -------------------------------------------------------------
	private String getProviderName(ServiceReference ref) {
		String providerName = (String) ref.getProperty(PERSISTENCE_PROVIDER);
		if (providerName == null) {
			System.out.println("Provider service registered without name property");
			throw new RuntimeException("Provider service registered without name property");
		}
		return providerName;
	}

	private void log(String message) {
		System.out.println("ProviderTracker: " + message);
	}
}