org.osgi.framework

Interface ServiceObjects<S>

Type Parameters:

S - Type of Service

@ProviderType
public interface ServiceObjects<S>

Allows multiple service objects for a service to be obtained.

For services with prototype scope, multiple service objects for the service can be obtained. Since implementations of PrototypeServiceFactory can return the same service object repeatedly, the framework must use count the returned service objects to release the service object only when its use count returns to zero.

For services with singleton or bundle scope, only one, use-counted service object is available to a requesting bundle.

Any unreleased service objects obtained from this ServiceObjects object are automatically released by the framework when the bundle associated with the BundleContext used to create this ServiceObjects object is stopped.

Since:

1.8

See Also:

BundleContext.getServiceObjects(ServiceReference), PrototypeServiceFactory

"ThreadSafe"

Method Summary

Modifier and Type	Method and Description
S	getService() Returns a service object for the associated service.
ServiceReference<S>	getServiceReference() Returns the ServiceReference for the service associated with this ServiceObjects object.
void	ungetService(S service) Releases a service object for the associated service.

Method Detail

getService

S getService()

Returns a service object for the associated service.

This ServiceObjects object can be used to obtain multiple service objects for the associated service if the service has prototype scope.

If the associated service has singleton or bundle scope, this method behaves the same as calling the BundleContext.getService(ServiceReference) method for the associated service. That is, only one, use-counted service object is available from this ServiceObjects object.

This method will always return null when the associated service has been unregistered.

For a prototype scope service, the following steps are required to obtain a service object:

1. If the associated service has been unregistered, null is returned.
2. The PrototypeServiceFactory.getService(Bundle, ServiceRegistration) method is called to supply a customized service object for the caller.
3. If the service object returned by the PrototypeServiceFactory object is null, not an instanceof all the classes named when the service was registered or the PrototypeServiceFactory object throws an exception, null is returned and a Framework event of type FrameworkEvent.ERROR containing a ServiceException describing the error is fired.
4. The use count for the customized service object is incremented by one.
5. The customized service object is returned.

Returns:

A service object for the associated service or null if the service is not registered, the customized service object returned by a ServiceFactory does not implement the classes under which it was registered or the ServiceFactory threw an exception.

Throws:

java.lang.IllegalStateException - If the BundleContext used to create this ServiceObjects object is no longer valid.

See Also:

ungetService(Object)

ungetService

void ungetService(S service)

Releases a service object for the associated service.

This ServiceObjects object can be used to obtain multiple service objects for the associated service if the service has prototype scope. If the associated service has singleton or bundle scope, this method behaves the same as calling the BundleContext.ungetService(ServiceReference) method for the associated service. That is, only one, use-counted service object is available from this ServiceObjects object.

For a prototype scope service, the following steps are required to release a service object:

1. If the associated service has been unregistered, this method returns without doing anything.
2. The use count for the specified service object is decremented by one.
3. If the use count for the specified service object is now zero, the PrototypeServiceFactory.ungetService(Bundle, ServiceRegistration, Object) method is called to release the specified service object.

The specified service object must no longer be used and all references to it should be destroyed after calling this method when the use count has returned to zero.

Parameters:

service - A service object previously provided by this ServiceObjects object.

Throws:

java.lang.IllegalStateException - If the BundleContext used to create this ServiceObjects object is no longer valid.

java.lang.IllegalArgumentException - If the specified service object is null or was not provided by a ServiceObjects object for the associated service.

See Also:

getService()

getServiceReference

ServiceReference<S> getServiceReference()

Returns the ServiceReference for the service associated with this ServiceObjects object.

Returns:

The ServiceReference for the service associated with this ServiceObjects object.