org.osgi.util.tracker.ServiceTracker Class Reference

Inheritance diagram for org.osgi.util.tracker.ServiceTracker:

org.osgi.util.tracker.ServiceTrackerCustomizer

List of all members.


Detailed Description

The ServiceTracker class simplifies using services from the Framework's service registry.

A ServiceTracker object is constructed with search criteria and a ServiceTrackerCustomizer object. A ServiceTracker object can use the ServiceTrackerCustomizer object to customize the service objects to be tracked. The ServiceTracker object can then be opened to begin tracking all services in the Framework's service registry that match the specified search criteria. The ServiceTracker object correctly handles all of the details of listening to ServiceEvent objects and getting and ungetting services.

The getServiceReferences method can be called to get references to the services being tracked. The getService and getServices methods can be called to get the service objects for the tracked service.

Version:
Revision
1.20

Definition at line 46 of file ServiceTracker.java.


Public Member Functions

 ServiceTracker (BundleContext context, ServiceReference reference, ServiceTrackerCustomizer customizer)
 Create a ServiceTracker object on the specified ServiceReference object.
 ServiceTracker (BundleContext context, String clazz, ServiceTrackerCustomizer customizer)
 Create a ServiceTracker object on the specified class name.
 ServiceTracker (BundleContext context, Filter filter, ServiceTrackerCustomizer customizer)
 Create a ServiceTracker object on the specified Filter object.
void open ()
 Open this ServiceTracker object and begin tracking services.
synchronized void open (boolean trackAllServices)
 Open this ServiceTracker object and begin tracking services.
synchronized void close ()
 Close this ServiceTracker object.
Object addingService (ServiceReference reference)
 Default implementation of the ServiceTrackerCustomizer.addingService method.
void modifiedService (ServiceReference reference, Object service)
 Default implementation of the ServiceTrackerCustomizer.modifiedService method.
void removedService (ServiceReference reference, Object service)
 Default implementation of the ServiceTrackerCustomizer.removedService method.
Object waitForService (long timeout) throws InterruptedException
 Wait for at least one service to be tracked by this ServiceTracker object.
ServiceReference[] getServiceReferences ()
 Return an array of ServiceReference objects for all services being tracked by this ServiceTracker object.
ServiceReference getServiceReference ()
 Returns a ServiceReference object for one of the services being tracked by this ServiceTracker object.
Object getService (ServiceReference reference)
 Returns the service object for the specified ServiceReference object if the referenced service is being tracked by this ServiceTracker object.
Object[] getServices ()
 Return an array of service objects for all services being tracked by this ServiceTracker object.
Object getService ()
 Returns a service object for one of the services being tracked by this ServiceTracker object.
void remove (ServiceReference reference)
 Remove a service from this ServiceTracker object.
int size ()
 Return the number of services being tracked by this ServiceTracker object.
int getTrackingCount ()
 Returns the tracking count for this ServiceTracker object.

Protected Member Functions

void finalize () throws Throwable
 Finalize.

Protected Attributes

final BundleContext context
 Bundle context this ServiceTracker object is tracking against.
final Filter filter
 Filter specifying search criteria for the services to track.

Package Functions

void modified ()
 Called by the Tracked object whenever the set of tracked services is modified.

Package Attributes

final ServiceTrackerCustomizer customizer
 ServiceTrackerCustomizer object for this tracker.
final String listenerFilter
 Filter string for use when adding the ServiceListener.

Classes

class  AllTracked
 Subclass of Tracked which implements the AllServiceListener interface. More...
class  Tracked
 Inner class to track services. More...

Constructor & Destructor Documentation

org.osgi.util.tracker.ServiceTracker.ServiceTracker ( BundleContext  context,
ServiceReference  reference,
ServiceTrackerCustomizer  customizer 
)

Create a ServiceTracker object on the specified ServiceReference object.

The service referenced by the specified ServiceReference object will be tracked by this ServiceTracker object.

Parameters:
context BundleContext object against which the tracking is done.
reference ServiceReference object for the service to be tracked.
customizer The customizer object to call when services are added, modified, or removed in this ServiceTracker object. If customizer is null, then this ServiceTracker object will be used as the ServiceTrackerCustomizer object and the ServiceTracker object will call the ServiceTrackerCustomizer methods on itself.

Definition at line 125 of file ServiceTracker.java.

References org.osgi.framework.BundleContext.createFilter(), org.osgi.framework.ServiceReference.getProperty(), and org.osgi.util.tracker.ServiceTracker.listenerFilter.

org.osgi.util.tracker.ServiceTracker.ServiceTracker ( BundleContext  context,
String  clazz,
ServiceTrackerCustomizer  customizer 
)

Create a ServiceTracker object on the specified class name.

Services registered under the specified class name will be tracked by this ServiceTracker object.

Parameters:
context BundleContext object against which the tracking is done.
clazz Class name of the services to be tracked.
customizer The customizer object to call when services are added, modified, or removed in this ServiceTracker object. If customizer is null, then this ServiceTracker object will be used as the ServiceTrackerCustomizer object and the ServiceTracker object will call the ServiceTrackerCustomizer methods on itself.

Definition at line 162 of file ServiceTracker.java.

References org.osgi.framework.BundleContext.createFilter(), and org.osgi.util.tracker.ServiceTracker.listenerFilter.

org.osgi.util.tracker.ServiceTracker.ServiceTracker ( BundleContext  context,
Filter  filter,
ServiceTrackerCustomizer  customizer 
)

Create a ServiceTracker object on the specified Filter object.

Services which match the specified Filter object will be tracked by this ServiceTracker object.

Parameters:
context BundleContext object against which the tracking is done.
filter Filter object to select the services to be tracked.
customizer The customizer object to call when services are added, modified, or removed in this ServiceTracker object. If customizer is null, then this ServiceTracker object will be used as the ServiceTrackerCustomizer object and the ServiceTracker object will call the ServiceTrackerCustomizer methods on itself.
Since:
1.1

Definition at line 200 of file ServiceTracker.java.


Member Function Documentation

void org.osgi.util.tracker.ServiceTracker.open (  ) 

Open this ServiceTracker object and begin tracking services.

This method calls open(false).

Exceptions:
java.lang.IllegalStateException if the BundleContext object with which this ServiceTracker object was created is no longer valid.
See also:
open(boolean)

Definition at line 228 of file ServiceTracker.java.

Referenced by org.openmobileis.bundle.osgi.synchro.BaseBundleLoaderActivator.start().

synchronized void org.osgi.util.tracker.ServiceTracker.open ( boolean  trackAllServices  ) 

Open this ServiceTracker object and begin tracking services.

Services which match the search criteria specified when this ServiceTracker object was created are now tracked by this ServiceTracker object.

Parameters:
trackAllServices If true, then this ServiceTracker will track all matching services regardless of class loader accessibility. If false, then this ServiceTracker will only track matching services which are class loader accessibile to the bundle whose BundleContext is used by this ServiceTracker.
Exceptions:
java.lang.IllegalStateException if the BundleContext object with which this ServiceTracker object was created is no longer valid.
Since:
1.3

Definition at line 253 of file ServiceTracker.java.

References org.osgi.framework.BundleContext.addServiceListener(), org.osgi.util.tracker.ServiceTracker.context, org.osgi.util.tracker.ServiceTracker.filter, org.osgi.util.tracker.ServiceTracker.listenerFilter, org.osgi.util.tracker.ServiceTracker.Tracked.setInitialServices(), org.osgi.framework.Filter.toString(), and org.osgi.util.tracker.ServiceTracker.Tracked.trackInitialServices().

synchronized void org.osgi.util.tracker.ServiceTracker.close (  ) 

Close this ServiceTracker object.

This method should be called when this ServiceTracker object should end the tracking of services.

Definition at line 322 of file ServiceTracker.java.

References org.osgi.util.tracker.ServiceTracker.Tracked.close(), org.osgi.util.tracker.ServiceTracker.context, org.osgi.util.tracker.ServiceTracker.filter, org.osgi.util.tracker.ServiceTracker.getServiceReferences(), org.osgi.framework.BundleContext.removeServiceListener(), and org.osgi.util.tracker.ServiceTracker.Tracked.untrack().

Object org.osgi.util.tracker.ServiceTracker.addingService ( ServiceReference  reference  ) 

Default implementation of the ServiceTrackerCustomizer.addingService method.

This method is only called when this ServiceTracker object has been constructed with a null ServiceTrackerCustomizer argument.

The default implementation returns the result of calling getService, on the BundleContext object with which this ServiceTracker object was created, passing the specified ServiceReference object.

This method can be overridden in a subclass to customize the service object to be tracked for the service being added. In that case, take care not to rely on the default implementation of removedService that will unget the service.

Parameters:
reference Reference to service being added to this ServiceTracker object.
Returns:
The service object to be tracked for the service added to this ServiceTracker object.
See also:
ServiceTrackerCustomizer

Implements org.osgi.util.tracker.ServiceTrackerCustomizer.

Definition at line 378 of file ServiceTracker.java.

References org.osgi.util.tracker.ServiceTracker.context, and org.osgi.framework.BundleContext.getService().

void org.osgi.util.tracker.ServiceTracker.modifiedService ( ServiceReference  reference,
Object  service 
)

Default implementation of the ServiceTrackerCustomizer.modifiedService method.

This method is only called when this ServiceTracker object has been constructed with a null ServiceTrackerCustomizer argument.

The default implementation does nothing.

Parameters:
reference Reference to modified service.
service The service object for the modified service.
See also:
ServiceTrackerCustomizer

Implements org.osgi.util.tracker.ServiceTrackerCustomizer.

Definition at line 397 of file ServiceTracker.java.

void org.osgi.util.tracker.ServiceTracker.removedService ( ServiceReference  reference,
Object  service 
)

Default implementation of the ServiceTrackerCustomizer.removedService method.

This method is only called when this ServiceTracker object has been constructed with a null ServiceTrackerCustomizer argument.

The default implementation calls ungetService, on the BundleContext object with which this ServiceTracker object was created, passing the specified ServiceReference object.

This method can be overridden in a subclass. If the default implementation of addingService method was used, this method must unget the service.

Parameters:
reference Reference to removed service.
service The service object for the removed service.
See also:
ServiceTrackerCustomizer

Implements org.osgi.util.tracker.ServiceTrackerCustomizer.

Definition at line 422 of file ServiceTracker.java.

References org.osgi.util.tracker.ServiceTracker.context, and org.osgi.framework.BundleContext.ungetService().

Object org.osgi.util.tracker.ServiceTracker.waitForService ( long  timeout  )  throws InterruptedException

Wait for at least one service to be tracked by this ServiceTracker object.

It is strongly recommended that waitForService is not used during the calling of the BundleActivator methods. BundleActivator methods are expected to complete in a short period of time.

Parameters:
timeout time interval in milliseconds to wait. If zero, the method will wait indefinately.
Returns:
Returns the result of getService().
Exceptions:
InterruptedException If another thread has interrupted the current thread.
IllegalArgumentException If the value of timeout is negative.

Definition at line 442 of file ServiceTracker.java.

References org.osgi.util.tracker.ServiceTracker.getService().

ServiceReference [] org.osgi.util.tracker.ServiceTracker.getServiceReferences (  ) 

Return an array of ServiceReference objects for all services being tracked by this ServiceTracker object.

Returns:
Array of ServiceReference objects or null if no service are being tracked.

Definition at line 475 of file ServiceTracker.java.

Referenced by org.osgi.util.tracker.ServiceTracker.close(), org.osgi.util.tracker.ServiceTracker.getServiceReference(), and org.osgi.util.tracker.ServiceTracker.getServices().

ServiceReference org.osgi.util.tracker.ServiceTracker.getServiceReference (  ) 

Returns a ServiceReference object for one of the services being tracked by this ServiceTracker object.

If multiple services are being tracked, the service with the highest ranking (as specified in its service.ranking property) is returned.

If there is a tie in ranking, the service with the lowest service ID (as specified in its service.id property); that is, the service that was registered first is returned.

This is the same algorithm used by BundleContext.getServiceReference.

Returns:
ServiceReference object or null if no service is being tracked.
Since:
1.1

Definition at line 518 of file ServiceTracker.java.

References org.osgi.util.tracker.ServiceTracker.filter, org.osgi.framework.ServiceReference.getProperty(), and org.osgi.util.tracker.ServiceTracker.getServiceReferences().

Referenced by org.osgi.util.tracker.ServiceTracker.getService().

Object org.osgi.util.tracker.ServiceTracker.getService ( ServiceReference  reference  ) 

Returns the service object for the specified ServiceReference object if the referenced service is being tracked by this ServiceTracker object.

Parameters:
reference Reference to the desired service.
Returns:
Service object or null if the service referenced by the specified ServiceReference object is not being tracked.

Definition at line 589 of file ServiceTracker.java.

Object [] org.osgi.util.tracker.ServiceTracker.getServices (  ) 

Return an array of service objects for all services being tracked by this ServiceTracker object.

Returns:
Array of service objects or null if no service are being tracked.

Definition at line 609 of file ServiceTracker.java.

References org.osgi.util.tracker.ServiceTracker.getService(), and org.osgi.util.tracker.ServiceTracker.getServiceReferences().

Object org.osgi.util.tracker.ServiceTracker.getService (  ) 

Returns a service object for one of the services being tracked by this ServiceTracker object.

If any services are being tracked, this method returns the result of calling getService(getServiceReference()).

Returns:
Service object or null if no service is being tracked.

Definition at line 642 of file ServiceTracker.java.

References org.osgi.util.tracker.ServiceTracker.filter, and org.osgi.util.tracker.ServiceTracker.getServiceReference().

Referenced by org.osgi.util.tracker.ServiceTracker.getServices(), and org.osgi.util.tracker.ServiceTracker.waitForService().

void org.osgi.util.tracker.ServiceTracker.remove ( ServiceReference  reference  ) 

Remove a service from this ServiceTracker object.

The specified service will be removed from this ServiceTracker object. If the specified service was being tracked then the ServiceTrackerCustomizer.removedService method will be called for that service.

Parameters:
reference Reference to the service to be removed.

Definition at line 671 of file ServiceTracker.java.

References org.osgi.util.tracker.ServiceTracker.Tracked.untrack().

int org.osgi.util.tracker.ServiceTracker.size (  ) 

Return the number of services being tracked by this ServiceTracker object.

Returns:
Number of services being tracked.

Definition at line 688 of file ServiceTracker.java.

Referenced by org.osgi.util.tracker.ServiceTracker.Tracked.setInitialServices().

int org.osgi.util.tracker.ServiceTracker.getTrackingCount (  ) 

Returns the tracking count for this ServiceTracker object.

The tracking count is initialized to 0 when this ServiceTracker object is opened. Every time a service is added or removed from this ServiceTracker object the tracking count is incremented.

The tracking count can be used to determine if this ServiceTracker object has added or removed a service by comparing a tracking count value previously collected with the current tracking count value. If the value has not changed, then no service has been added or removed from this ServiceTracker object since the previous tracking count was collected.

Since:
1.2
Returns:
The tracking count for this ServiceTracker object or -1 if this ServiceTracker object is not open.

Definition at line 719 of file ServiceTracker.java.

void org.osgi.util.tracker.ServiceTracker.modified (  )  [package]

Called by the Tracked object whenever the set of tracked services is modified.

Increments the tracking count and clears the cache.

Definition at line 732 of file ServiceTracker.java.

References org.osgi.util.tracker.ServiceTracker.filter.

Referenced by org.osgi.util.tracker.ServiceTracker.Tracked.track(), and org.osgi.util.tracker.ServiceTracker.Tracked.untrack().

void org.osgi.util.tracker.ServiceTracker.finalize (  )  throws Throwable [protected]

Finalize.

This method no longer performs any function but it kept to maintain binary compatibility with prior versions of this class.

Definition at line 745 of file ServiceTracker.java.


Member Data Documentation

final Filter org.osgi.util.tracker.ServiceTracker.filter [protected]

Filter specifying search criteria for the services to track.

Since:
1.1

Definition at line 59 of file ServiceTracker.java.

Referenced by org.osgi.util.tracker.ServiceTracker.close(), org.osgi.util.tracker.ServiceTracker.getService(), org.osgi.util.tracker.ServiceTracker.getServiceReference(), org.osgi.util.tracker.ServiceTracker.modified(), org.osgi.util.tracker.ServiceTracker.open(), and org.osgi.util.tracker.ServiceTracker.Tracked.serviceChanged().

final String org.osgi.util.tracker.ServiceTracker.listenerFilter [package]

Filter string for use when adding the ServiceListener.

If this field is set, then certain optimizations can be taken since we don't have a user supplied filter.

Definition at line 69 of file ServiceTracker.java.

Referenced by org.osgi.util.tracker.ServiceTracker.open(), org.osgi.util.tracker.ServiceTracker.Tracked.serviceChanged(), and org.osgi.util.tracker.ServiceTracker.ServiceTracker().


The documentation for this class was generated from the following file:
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