| /* |
| * Copyright (c) OSGi Alliance (2000, 2010). 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 {@code ServiceTrackerCustomizer} interface allows a |
| * {@code ServiceTracker} to customize the service objects that are |
| * tracked. A {@code ServiceTrackerCustomizer} is called when a service is |
| * being added to a {@code ServiceTracker}. The |
| * {@code ServiceTrackerCustomizer} can then return an object for the |
| * tracked service. A {@code ServiceTrackerCustomizer} is also called when |
| * a tracked service is modified or has been removed from a |
| * {@code ServiceTracker}. |
| * |
| * <p> |
| * The methods in this interface may be called as the result of a |
| * {@code ServiceEvent} being received by a {@code ServiceTracker}. |
| * Since {@code ServiceEvent}s are synchronously delivered by the |
| * Framework, it is highly recommended that implementations of these methods do |
| * not register ({@code BundleContext.registerService}), modify ( |
| * {@code ServiceRegistration.setProperties}) or unregister ( |
| * {@code ServiceRegistration.unregister}) a service while being |
| * synchronized on any object. |
| * |
| * <p> |
| * The {@code ServiceTracker} class is thread-safe. It does not call a |
| * {@code ServiceTrackerCustomizer} while holding any locks. |
| * {@code ServiceTrackerCustomizer} implementations must also be |
| * thread-safe. |
| * |
| * @param <S> The type of the service being tracked. |
| * @param <T> The type of the tracked object. |
| * @ThreadSafe |
| * @version $Id: c654a963336cee74762b8f54c8cef8d5774f8b4d $ |
| */ |
| public interface ServiceTrackerCustomizer<S, T> { |
| /** |
| * A service is being added to the {@code ServiceTracker}. |
| * |
| * <p> |
| * This method is called before a service which matched the search |
| * parameters of the {@code ServiceTracker} is added to the |
| * {@code ServiceTracker}. This method should return the service object |
| * to be tracked for the specified {@code ServiceReference}. The |
| * returned service object is stored in the {@code ServiceTracker} and |
| * is available from the {@code getService} and |
| * {@code getServices} methods. |
| * |
| * @param reference The reference to the service being added to the |
| * {@code ServiceTracker}. |
| * @return The service object to be tracked for the specified referenced |
| * service or {@code null} if the specified referenced service |
| * should not be tracked. |
| */ |
| public T addingService(ServiceReference<S> reference); |
| |
| /** |
| * A service tracked by the {@code ServiceTracker} has been modified. |
| * |
| * <p> |
| * This method is called when a service being tracked by the |
| * {@code 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<S> reference, T service); |
| |
| /** |
| * A service tracked by the {@code ServiceTracker} has been removed. |
| * |
| * <p> |
| * This method is called after a service is no longer being tracked by the |
| * {@code 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<S> reference, T service); |
| } |