Android APIs
public abstract class

PrintService

extends Service
java.lang.Object
   ↳ android.content.Context
     ↳ android.content.ContextWrapper
       ↳ android.app.Service
         ↳ android.printservice.PrintService

Class Overview

This is the base class for implementing print services. A print service knows how to discover and interact one or more printers via one or more protocols.

Printer discovery

A print service is responsible for discovering printers, adding discovered printers, removing added printers, and updating added printers. When the system is interested in printers managed by your service it will call onCreatePrinterDiscoverySession() from which you must return a new PrinterDiscoverySession instance. The returned session encapsulates the interaction between the system and your service during printer discovery. For description of this interaction refer to the documentation for PrinterDiscoverySession.

For every printer discovery session all printers have to be added since system does not retain printers across sessions. Hence, each printer known to this print service should be added only once during a discovery session. Only an already added printer can be removed or updated. Removed printers can be added again.

Print jobs

When a new print job targeted to a printer managed by this print service is is queued, i.e. ready for processing by the print service, you will receive a call to onPrintJobQueued(PrintJob). The print service may handle the print job immediately or schedule that for an appropriate time in the future. The list of all active print jobs for this service is obtained by calling getActivePrintJobs(). Active print jobs are ones that are queued or started.

A print service is responsible for setting a print job's state as appropriate while processing it. Initially, a print job is queued, i.e. PrintJob.isQueued() returns true, which means that the document to be printed is spooled by the system and the print service can begin processing it. You can obtain the printed document by calling PrintJob.getDocument() whose data is accessed via PrintDocument.getData(). After the print service starts printing the data it should set the print job's state to started by calling start() after which PrintJob.isStarted() would return true. Upon successful completion, the print job should be marked as completed by calling PrintJob.complete() after which PrintJob.isCompleted() would return true. In case of a failure, the print job should be marked as failed by calling PrintJob.fail( String) after which PrintJob.isFailed() would return true.

If a print job is queued or started and the user requests to cancel it, the print service will receive a call to onRequestCancelPrintJob(PrintJob) which requests from the service to do best effort in canceling the job. In case the job is successfully canceled, its state has to be marked as cancelled by calling PrintJob.cancel() after which PrintJob.isCacnelled() would return true.

Lifecycle

The lifecycle of a print service is managed exclusively by the system and follows the established service lifecycle. Additionally, starting or stopping a print service is triggered exclusively by an explicit user action through enabling or disabling it in the device settings. After the system binds to a print service, it calls onConnected(). This method can be overriden by clients to perform post binding setup. Also after the system unbinds from a print service, it calls onDisconnected(). This method can be overriden by clients to perform post unbinding cleanup. Your should not do any work after the system disconnected from your print service since the service can be killed at any time to reclaim memory. The system will not disconnect from a print service if there are active print jobs for the printers managed by it.

Declaration

A print service is declared as any other service in an AndroidManifest.xml but it must also specify that it handles the Intent with action android.printservice.PrintService. Failure to declare this intent will cause the system to ignore the print service. Additionally, a print service must request the android.permission.BIND_PRINT_SERVICE permission to ensure that only the system can bind to it. Failure to declare this intent will cause the system to ignore the print service. Following is an example declaration:

 <service android:name=".MyPrintService"
         android:permission="android.permission.BIND_PRINT_SERVICE">
     <intent-filter>
         <action android:name="android.printservice.PrintService" />
     </intent-filter>
     . . .
 </service>
 

Configuration

A print service can be configured by specifying an optional settings activity which exposes service specific settings, an optional add printers activity which is used for manual addition of printers, vendor name ,etc. It is a responsibility of the system to launch the settings and add printers activities when appropriate.

A print service is configured by providing a meta-data entry in the manifest when declaring the service. A service declaration with a meta-data tag is presented below:

 <service android:name=".MyPrintService"
         android:permission="android.permission.BIND_PRINT_SERVICE">
     <intent-filter>
         <action android:name="android.printservice.PrintService" />
     </intent-filter>
     <meta-data android:name="android.printservice" android:resource="@xml/printservice" />
 </service>

For more details for how to configure your print service via the meta-data refer to SERVICE_META_DATA and <print-service>.

Note: All callbacks in this class are executed on the main application thread. You should also invoke any method of this class on the main application thread.

Summary

Constants
String EXTRA_PRINTER_INFO If you declared an optional activity with advanced print options via the advancedPrintOptionsActivity attribute, this extra is used to pass in the currently selected printer's PrinterInfo to your activity allowing you to inspect it.
String EXTRA_PRINT_DOCUMENT_INFO If you declared an optional activity with advanced print options via the advancedPrintOptionsActivity attribute, this extra is used to pass in the meta-data for the currently printed document as a PrintDocumentInfo to your activity allowing you to inspect it.
String EXTRA_PRINT_JOB_INFO If you declared an optional activity with advanced print options via the advancedPrintOptionsActivity attribute, this extra is used to pass in the currently constructed PrintJobInfo to your activity allowing you to modify it.
String SERVICE_INTERFACE The Intent action that must be declared as handled by a service in its manifest for the system to recognize it as a print service.
String SERVICE_META_DATA Name under which a PrintService component publishes additional information about itself.
[Expand]
Inherited Constants
From class android.app.Service
From class android.content.Context
From interface android.content.ComponentCallbacks2
Public Constructors
PrintService()
Public Methods
final PrinterId generatePrinterId(String localId)
Generates a global printer id given the printer's locally unique one.
final List<PrintJob> getActivePrintJobs()
Gets the active print jobs for the printers managed by this service.
final IBinder onBind(Intent intent)
Return the communication channel to the service.
Protected Methods
final void attachBaseContext(Context base)
Set the base context for this ContextWrapper.
void onConnected()
The system has connected to this service.
abstract PrinterDiscoverySession onCreatePrinterDiscoverySession()
Callback asking you to create a new PrinterDiscoverySession.
void onDisconnected()
The system has disconnected from this service.
abstract void onPrintJobQueued(PrintJob printJob)
Called when there is a queued print job for one of the printers managed by this print service.
abstract void onRequestCancelPrintJob(PrintJob printJob)
Called when cancellation of a print job is requested.
[Expand]
Inherited Methods
From class android.app.Service
From class android.content.ContextWrapper
From class android.content.Context
From class java.lang.Object
From interface android.content.ComponentCallbacks2
From interface android.content.ComponentCallbacks

Constants

public static final String EXTRA_PRINTER_INFO

Added in API level 21

If you declared an optional activity with advanced print options via the advancedPrintOptionsActivity attribute, this extra is used to pass in the currently selected printer's PrinterInfo to your activity allowing you to inspect it.

Constant Value: "android.intent.extra.print.EXTRA_PRINTER_INFO"

public static final String EXTRA_PRINT_DOCUMENT_INFO

Added in API level 23

If you declared an optional activity with advanced print options via the advancedPrintOptionsActivity attribute, this extra is used to pass in the meta-data for the currently printed document as a PrintDocumentInfo to your activity allowing you to inspect it.

Constant Value: "android.printservice.extra.PRINT_DOCUMENT_INFO"

public static final String EXTRA_PRINT_JOB_INFO

Added in API level 19

If you declared an optional activity with advanced print options via the advancedPrintOptionsActivity attribute, this extra is used to pass in the currently constructed PrintJobInfo to your activity allowing you to modify it. After you are done, you must return the modified PrintJobInfo via the same extra.

You cannot modify the passed in PrintJobInfo directly, rather you should build another one using the PrintJobInfo.Builder class. You can specify any standard properties and add advanced, printer specific, ones via PrintJobInfo.Builder.putAdvancedOption(String, String) and PrintJobInfo.Builder.putAdvancedOption(String, int). The advanced options are not interpreted by the system, they will not be visible to applications, and can only be accessed by your print service via PrintJob.getAdvancedStringOption(String) and PrintJob.getAdvancedIntOption(String).

If the advanced print options activity offers changes to the standard print options, you can get the current PrinterInfo using the EXTRA_PRINTER_INFO extra which will allow you to present the user with UI options supported by the current printer. For example, if the current printer does not support a given media size, you should not offer it in the advanced print options UI.

See also:

Constant Value: "android.intent.extra.print.PRINT_JOB_INFO"

public static final String SERVICE_INTERFACE

Added in API level 19

The Intent action that must be declared as handled by a service in its manifest for the system to recognize it as a print service.

Constant Value: "android.printservice.PrintService"

public static final String SERVICE_META_DATA

Added in API level 19

Name under which a PrintService component publishes additional information about itself. This meta-data must reference a XML resource containing a <print-service> tag. This is a sample XML file configuring a print service:

 <print-service
     android:vendor="SomeVendor"
     android:settingsActivity="foo.bar.MySettingsActivity"
     andorid:addPrintersActivity="foo.bar.MyAddPrintersActivity."
     . . .
 />

For detailed configuration options that can be specified via the meta-data refer to android.R.styleable.PrintService.

If you declare a settings or add a printers activity, they have to be exported, by setting the exported activity attribute to true . Also in case you want only the system to be able to start any of these activities you can specify that they request the android.permission .START_PRINT_SERVICE_CONFIG_ACTIVITY permission by setting the permission activity attribute.

Constant Value: "android.printservice"

Public Constructors

public PrintService ()

Added in API level 19

Public Methods

public final PrinterId generatePrinterId (String localId)

Added in API level 19

Generates a global printer id given the printer's locally unique one.

Parameters
localId String: A locally unique id in the context of your print service.
Returns
PrinterId Global printer id.

public final List<PrintJob> getActivePrintJobs ()

Added in API level 19

Gets the active print jobs for the printers managed by this service. Active print jobs are ones that are not in a final state, i.e. whose state is queued or started.

Returns
List<PrintJob> The active print jobs.

public final IBinder onBind (Intent intent)

Added in API level 19

Return the communication channel to the service. May return null if clients can not bind to the service. The returned IBinder is usually for a complex interface that has been described using aidl.

Note that unlike other application components, calls on to the IBinder interface returned here may not happen on the main thread of the process. More information about the main thread can be found in Processes and Threads.

Parameters
intent Intent: The Intent that was used to bind to this service, as given to Context.bindService. Note that any extras that were included with the Intent at that point will not be seen here.
Returns
IBinder Return an IBinder through which clients can call on to the service.

Protected Methods

protected final void attachBaseContext (Context base)

Added in API level 19

Set the base context for this ContextWrapper. All calls will then be delegated to the base context. Throws IllegalStateException if a base context has already been set.

Parameters
base Context: The new base context for this wrapper.

protected void onConnected ()

Added in API level 19

The system has connected to this service.

protected abstract PrinterDiscoverySession onCreatePrinterDiscoverySession ()

Added in API level 19

Callback asking you to create a new PrinterDiscoverySession.

Returns
PrinterDiscoverySession

protected void onDisconnected ()

Added in API level 19

The system has disconnected from this service.

protected abstract void onPrintJobQueued (PrintJob printJob)

Added in API level 19

Called when there is a queued print job for one of the printers managed by this print service.

Parameters
printJob PrintJob: The new queued print job.

protected abstract void onRequestCancelPrintJob (PrintJob printJob)

Added in API level 19

Called when cancellation of a print job is requested. The service should do best effort to fulfill the request. After the cancellation is performed, the print job should be marked as cancelled state by calling cancel().

Parameters
printJob PrintJob: The print job to cancel.