org.osgi.util.tracker.ServiceTrackerCustomizer Maven / Gradle / Ivy
/*
* Copyright (c) OSGi Alliance (2000, 2008). All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.osgi.util.tracker;
import org.osgi.framework.ServiceReference;
/**
* The ServiceTrackerCustomizer interface allows a
* ServiceTracker to customize the service objects that are
* tracked. A ServiceTrackerCustomizer is called when a service is
* being added to a ServiceTracker. The
* ServiceTrackerCustomizer can then return an object for the
* tracked service. A ServiceTrackerCustomizer is also called when
* a tracked service is modified or has been removed from a
* ServiceTracker.
*
*
* The methods in this interface may be called as the result of a
* ServiceEvent being received by a ServiceTracker.
* Since ServiceEvents are synchronously delivered by the
* Framework, it is highly recommended that implementations of these methods do
* not register (BundleContext.registerService), modify (
* ServiceRegistration.setProperties) or unregister (
* ServiceRegistration.unregister) a service while being
* synchronized on any object.
*
*
* The ServiceTracker class is thread-safe. It does not call a
* ServiceTrackerCustomizer while holding any locks.
* ServiceTrackerCustomizer implementations must also be
* thread-safe.
*
* @ThreadSafe
* @version $Revision: 5874 $
*/
public interface ServiceTrackerCustomizer {
/**
* A service is being added to the ServiceTracker.
*
*
* This method is called before a service which matched the search
* parameters of the ServiceTracker is added to the
* ServiceTracker. This method should return the service object
* to be tracked for the specified ServiceReference. The
* returned service object is stored in the ServiceTracker and
* is available from the getService and
* getServices methods.
*
* @param reference The reference to the service being added to the
* ServiceTracker.
* @return The service object to be tracked for the specified referenced
* service or null if the specified referenced service
* should not be tracked.
*/
public Object addingService(ServiceReference reference);
/**
* A service tracked by the ServiceTracker has been modified.
*
*
* This method is called when a service being tracked by the
* ServiceTracker has had it properties modified.
*
* @param reference The reference to the service that has been modified.
* @param service The service object for the specified referenced service.
*/
public void modifiedService(ServiceReference reference, Object service);
/**
* A service tracked by the ServiceTracker has been removed.
*
*
* This method is called after a service is no longer being tracked by the
* ServiceTracker.
*
* @param reference The reference to the service that has been removed.
* @param service The service object for the specified referenced service.
*/
public void removedService(ServiceReference reference, Object service);
}