/*
* Javolution - Java(TM) Solution for Real-Time and Embedded Systems
* Copyright (C) 2012 - Javolution (http://javolution.org/)
* All rights reserved.
*
* Permission to use, copy, modify, and distribute this software is
* freely granted, provided that this notice is preserved.
*/
package javolution.osgi.internal;
import org.osgi.framework.BundleContext;
import org.osgi.util.tracker.ServiceTracker;
/**
* Bridge to service tracker (does not trigger class loading exception if running outside OSGi).
*/
public final class ServiceTrackerImpl<C> {
private volatile ServiceTracker tracker;
private final Class<C> type;
private final Class<? extends C> defaultImplClass;
private C defaultImpl;
/** Creates a context tracker for the specified context type. */
public ServiceTrackerImpl(final Class<C> type, final Class<? extends C> defaultImplClass) {
this.defaultImplClass = defaultImplClass;
this.type = type;
}
/** Activates OSGi tracking. */
public void activate(final BundleContext bc) {
ServiceTracker trk = new ServiceTracker(bc, type.getName(), null);
trk.open();
tracker = trk;
}
/** Deactivates OSGi tracking. */
public void deactivate(final BundleContext bc) {
tracker.close();
tracker = null;
}
/** Returns the published services or the default implementation if none. */
public Object[] getServices() {
ServiceTracker trk = tracker;
if (trk != null) {
Object[] services = trk.getServices();
if (services != null)
return services;
}
synchronized (this) {
if (defaultImpl == null) {
try {
defaultImpl = defaultImplClass.newInstance();
} catch (Throwable error) {
throw new RuntimeException(error);
}
}
}
return new Object[] { defaultImpl };
}
}