ServiceLocator

package org.bytesparadise.tools.common.util;

import org.bytesparadise.tools.common.CommonBundleActivator;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;

/**
 * A Bundle-scoped utility class for Declarative Services location.
 * 
 * @author xcoulon
 * 
 */
//TODO : move to gist
public final class ServiceLocator {

	/**
	 * Default private constructor.
	 */
	private ServiceLocator() {
	}

	/**
	 * Locate the Declarative Service that implements the given class.
	 * 
	 * @param <T>
	 *            the class type of the Declarative Service to locate
	 * @param clazz
	 *            the Class of the Declarative Service to locate
	 * @return the located Declarative Service already casted in the type given
	 *         in parameter
	 */
	@SuppressWarnings("unchecked")
	public static <T> T locateService(final Class<T> clazz) {
		Bundle bundle = CommonBundleActivator.getDefault().getBundle();
		BundleContext context = bundle.getBundleContext();
		// DS implements laziness transparently
		// Obtain service reference
		ServiceReference reference = context.getServiceReference(clazz
				.getName());
		if (reference == null) {
			Logger.error("No reference found for service '"
					+ clazz.getName()
					+ "'. Check OSGI-INF/*.xml and MANIFEST.MF 'Service-Component' section");
			return null;
		}
		// Obtain service instance
		return (T) context.getService(reference);
	}
}