Package org.osgi.util.tracker

Interface ServiceTrackerCustomizer<S,​T>

  • Type Parameters:
    S - The type of the service being tracked.
    T - The type of the tracked object.
    All Known Implementing Classes:
    Logger, ObserverTracker, ServiceTracker, SortingServiceTracker, TikaActivator
    @ConsumerType
public interface ServiceTrackerCustomizer<S,​T>
    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.

    • Method Detail

      • addingService

        T addingService​(ServiceReference<S> reference)
        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.

        Parameters:
        reference - The reference to the service being added to the ServiceTracker.
        Returns:
        The service object to be tracked for the specified referenced service or null if the specified referenced service should not be tracked.

      • modifiedService

        void modifiedService​(ServiceReference<S> reference,
                     T service)
        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.

        Parameters:
        reference - The reference to the service that has been modified.
        service - The service object for the specified referenced service.

      • removedService

        void removedService​(ServiceReference<S> reference,
                    T 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.

        Parameters:
        reference - The reference to the service that has been removed.
        service - The service object for the specified referenced service.