PrintService.java revision b5f180608db6de123b54ae94de569ff1ebca705c
1/* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.printservice; 18 19import android.app.Service; 20import android.content.ComponentName; 21import android.content.Context; 22import android.content.Intent; 23import android.os.Handler; 24import android.os.IBinder; 25import android.os.Looper; 26import android.os.Message; 27import android.os.RemoteException; 28import android.print.PrintJobInfo; 29import android.print.PrinterId; 30import android.util.Log; 31 32import java.util.ArrayList; 33import java.util.Collections; 34import java.util.List; 35 36/** 37 * <p> 38 * This is the base class for implementing print services. A print service knows 39 * how to discover and interact one or more printers via one or more protocols. 40 * </p> 41 * <h3>Printer discovery</h3> 42 * <p> 43 * A print service is responsible for discovering printers, adding discovered printers, 44 * removing added printers, and updating added printers. When the system is interested 45 * in printers managed by your service it will call {@link 46 * #onCreatePrinterDiscoverySession()} from which you must return a new {@link 47 * PrinterDiscoverySession} instance. The returned session encapsulates the interaction 48 * between the system and your service during printer discovery. For description of this 49 * interaction refer to the documentation for {@link PrinterDiscoverySession}. 50 * </p> 51 * <p> 52 * For every printer discovery session all printers have to be added since system does 53 * not retain printers across sessions. Hence, each printer known to this print service 54 * should be added only once during a discovery session. Only an already added printer 55 * can be removed or updated. Removed printers can be added again. 56 * </p> 57 * <h3>Print jobs</h3> 58 * <p> 59 * When a new print job targeted to a printer managed by this print service is is queued, 60 * i.e. ready for processing by the print service, you will receive a call to {@link 61 * #onPrintJobQueued(PrintJob)}. The print service may handle the print job immediately 62 * or schedule that for an appropriate time in the future. The list of all active print 63 * jobs for this service is obtained by calling {@link #getActivePrintJobs()}. Active 64 * print jobs are ones that are queued or started. 65 * </p> 66 * <p> 67 * A print service is responsible for setting a print job's state as appropriate 68 * while processing it. Initially, a print job is queued, i.e. {@link PrintJob#isQueued() 69 * PrintJob.isQueued()} returns true, which means that the document to be printed is 70 * spooled by the system and the print service can begin processing it. You can obtain 71 * the printed document by calling {@link PrintJob#getDocument() PrintJob.getDocument()} 72 * whose data is accessed via {@link PrintDocument#getData() PrintDocument.getData()}. 73 * After the print service starts printing the data it should set the print job's 74 * state to started by calling {@link PrintJob#start()} after which 75 * {@link PrintJob#isStarted() PrintJob.isStarted()} would return true. Upon successful 76 * completion, the print job should be marked as completed by calling {@link 77 * PrintJob#complete() PrintJob.complete()} after which {@link PrintJob#isCompleted() 78 * PrintJob.isCompleted()} would return true. In case of a failure, the print job should 79 * be marked as failed by calling {@link PrintJob#fail(String) PrintJob.fail( 80 * String)} after which {@link PrintJob#isFailed() PrintJob.isFailed()} would 81 * return true. 82 * </p> 83 * <p> 84 * If a print job is queued or started and the user requests to cancel it, the print 85 * service will receive a call to {@link #onRequestCancelPrintJob(PrintJob)} which 86 * requests from the service to do best effort in canceling the job. In case the job 87 * is successfully canceled, its state has to be marked as cancelled by calling {@link 88 * PrintJob#cancel() PrintJob.cancel()} after which {@link PrintJob#isCancelled() 89 * PrintJob.isCacnelled()} would return true. 90 * </p> 91 * <h3>Lifecycle</h3> 92 * <p> 93 * The lifecycle of a print service is managed exclusively by the system and follows 94 * the established service lifecycle. Additionally, starting or stopping a print service 95 * is triggered exclusively by an explicit user action through enabling or disabling it 96 * in the device settings. After the system binds to a print service, it calls {@link 97 * #onConnected()}. This method can be overriden by clients to perform post binding setup. 98 * Also after the system unbinds from a print service, it calls {@link #onDisconnected()}. 99 * This method can be overriden by clients to perform post unbinding cleanup. Your should 100 * not do any work after the system disconnected from your print service since the 101 * service can be killed at any time to reclaim memory. The system will not disconnect 102 * from a print service if there are active print jobs for the printers managed by it. 103 * </p> 104 * <h3>Declaration</h3> 105 * <p> 106 * A print service is declared as any other service in an AndroidManifest.xml but it must 107 * also specify that it handles the {@link android.content.Intent} with action {@link 108 * #SERVICE_INTERFACE android.printservice.PrintService}. Failure to declare this intent 109 * will cause the system to ignore the print service. Additionally, a print service must 110 * request the {@link android.Manifest.permission#BIND_PRINT_SERVICE 111 * android.permission.BIND_PRINT_SERVICE} permission to ensure that only the system can 112 * bind to it. Failure to declare this intent will cause the system to ignore the print 113 * service. Following is an example declaration: 114 * </p> 115 * <pre> 116 * <service android:name=".MyPrintService" 117 * android:permission="android.permission.BIND_PRINT_SERVICE"> 118 * <intent-filter> 119 * <action android:name="android.printservice.PrintService" /> 120 * </intent-filter> 121 * . . . 122 * </service> 123 * </pre> 124 * <h3>Configuration</h3> 125 * <p> 126 * A print service can be configured by specifying an optional settings activity which 127 * exposes service specific settings, an optional add printers activity which is used for 128 * manual addition of printers, vendor name ,etc. It is a responsibility of the system 129 * to launch the settings and add printers activities when appropriate. 130 * </p> 131 * <p> 132 * A print service is configured by providing a {@link #SERVICE_META_DATA meta-data} 133 * entry in the manifest when declaring the service. A service declaration with a meta-data 134 * tag is presented below: 135 * <pre> <service android:name=".MyPrintService" 136 * android:permission="android.permission.BIND_PRINT_SERVICE"> 137 * <intent-filter> 138 * <action android:name="android.printservice.PrintService" /> 139 * </intent-filter> 140 * <meta-data android:name="android.printservice" android:resource="@xml/printservice" /> 141 * </service></pre> 142 * </p> 143 * <p> 144 * For more details for how to configure your print service via the meta-data refer to 145 * {@link #SERVICE_META_DATA} and <code><{@link android.R.styleable#PrintService 146 * print-service}></code>. 147 * </p> 148 * <p> 149 * <strong>Note: </strong> All callbacks in this class are executed on the main 150 * application thread. You should also invoke any method of this class on the main 151 * application thread. 152 * </p> 153 */ 154public abstract class PrintService extends Service { 155 156 private static final String LOG_TAG = "PrintService"; 157 158 private static final boolean DEBUG = false; 159 160 /** 161 * The {@link Intent} action that must be declared as handled by a service 162 * in its manifest for the system to recognize it as a print service. 163 */ 164 public static final String SERVICE_INTERFACE = "android.printservice.PrintService"; 165 166 /** 167 * Name under which a {@link PrintService} component publishes additional information 168 * about itself. This meta-data must reference a XML resource containing a <code> 169 * <{@link android.R.styleable#PrintService print-service}></code> tag. This is 170 * a sample XML file configuring a print service: 171 * <pre> <print-service 172 * android:vendor="SomeVendor" 173 * android:settingsActivity="foo.bar.MySettingsActivity" 174 * andorid:addPrintersActivity="foo.bar.MyAddPrintersActivity." 175 * . . . 176 * /></pre> 177 * <p> 178 * For detailed configuration options that can be specified via the meta-data 179 * refer to {@link android.R.styleable#PrintService android.R.styleable.PrintService}. 180 * </p> 181 * <p> 182 * If you declare a settings or add a printers activity, they have to be exported, 183 * by setting the {@link android.R.attr#exported} activity attribute to <code>true 184 * </code>. Also in case you want only the system to be able to start any of these 185 * activities you can specify that they request the android.permission 186 * .START_PRINT_SERVICE_CONFIG_ACTIVITY permission by setting the 187 * {@link android.R.attr#permission} activity attribute. 188 * </p> 189 */ 190 public static final String SERVICE_META_DATA = "android.printservice"; 191 192 private Handler mHandler; 193 194 private IPrintServiceClient mClient; 195 196 private int mLastSessionId = -1; 197 198 private PrinterDiscoverySession mDiscoverySession; 199 200 @Override 201 protected final void attachBaseContext(Context base) { 202 super.attachBaseContext(base); 203 mHandler = new ServiceHandler(base.getMainLooper()); 204 } 205 206 /** 207 * The system has connected to this service. 208 */ 209 protected void onConnected() { 210 /* do nothing */ 211 } 212 213 /** 214 * The system has disconnected from this service. 215 */ 216 protected void onDisconnected() { 217 /* do nothing */ 218 } 219 220 /** 221 * Callback asking you to create a new {@link PrinterDiscoverySession}. 222 * 223 * @see PrinterDiscoverySession 224 */ 225 protected abstract PrinterDiscoverySession onCreatePrinterDiscoverySession(); 226 227 /** 228 * Called when cancellation of a print job is requested. The service 229 * should do best effort to fulfill the request. After the cancellation 230 * is performed, the print job should be marked as cancelled state by 231 * calling {@link PrintJob#cancel()}. 232 * 233 * @param printJob The print job to cancel. 234 * 235 * @see PrintJob#cancel() PrintJob.cancel() 236 * @see PrintJob#isCancelled() PrintJob.isCancelled() 237 */ 238 protected abstract void onRequestCancelPrintJob(PrintJob printJob); 239 240 /** 241 * Called when there is a queued print job for one of the printers 242 * managed by this print service. 243 * 244 * @param printJob The new queued print job. 245 * 246 * @see PrintJob#isQueued() PrintJob.isQueued() 247 * @see #getActivePrintJobs() 248 */ 249 protected abstract void onPrintJobQueued(PrintJob printJob); 250 251 /** 252 * Gets the active print jobs for the printers managed by this service. 253 * Active print jobs are ones that are not in a final state, i.e. whose 254 * state is queued or started. 255 * 256 * @return The active print jobs. 257 * 258 * @see PrintJob#isQueued() PrintJob.isQueued() 259 * @see PrintJob#isStarted() PrintJob.isStarted() 260 */ 261 public final List<PrintJob> getActivePrintJobs() { 262 throwIfNotCalledOnMainThread(); 263 if (mClient == null) { 264 return Collections.emptyList(); 265 } 266 try { 267 List<PrintJob> printJobs = null; 268 List<PrintJobInfo> printJobInfos = mClient.getPrintJobInfos(); 269 if (printJobInfos != null) { 270 final int printJobInfoCount = printJobInfos.size(); 271 printJobs = new ArrayList<PrintJob>(printJobInfoCount); 272 for (int i = 0; i < printJobInfoCount; i++) { 273 printJobs.add(new PrintJob(printJobInfos.get(i), mClient)); 274 } 275 } 276 if (printJobs != null) { 277 return printJobs; 278 } 279 } catch (RemoteException re) { 280 Log.e(LOG_TAG, "Error calling getPrintJobs()", re); 281 } 282 return Collections.emptyList(); 283 } 284 285 /** 286 * Generates a global printer id given the printer's locally unique one. 287 * 288 * @param localId A locally unique id in the context of your print service. 289 * @return Global printer id. 290 */ 291 public final PrinterId generatePrinterId(String localId) { 292 throwIfNotCalledOnMainThread(); 293 return new PrinterId(new ComponentName(getPackageName(), 294 getClass().getName()), localId); 295 } 296 297 static void throwIfNotCalledOnMainThread() { 298 if (!Looper.getMainLooper().isCurrentThread()) { 299 throw new IllegalAccessError("must be called from the main thread"); 300 } 301 } 302 303 @Override 304 public final IBinder onBind(Intent intent) { 305 return new IPrintService.Stub() { 306 @Override 307 public void createPrinterDiscoverySession() { 308 mHandler.sendEmptyMessage(ServiceHandler.MSG_CREATE_PRINTER_DISCOVERY_SESSION); 309 } 310 311 @Override 312 public void destroyPrinterDiscoverySession() { 313 mHandler.sendEmptyMessage(ServiceHandler.MSG_DESTROY_PRINTER_DISCOVERY_SESSION); 314 } 315 316 public void startPrinterDiscovery(List<PrinterId> priorityList) { 317 mHandler.obtainMessage(ServiceHandler.MSG_START_PRINTER_DISCOVERY, 318 priorityList).sendToTarget(); 319 } 320 321 @Override 322 public void stopPrinterDiscovery() { 323 mHandler.sendEmptyMessage(ServiceHandler.MSG_STOP_PRINTER_DISCOVERY); 324 } 325 326 @Override 327 public void validatePrinters(List<PrinterId> printerIds) { 328 mHandler.obtainMessage(ServiceHandler.MSG_VALIDATE_PRINTERS, 329 printerIds).sendToTarget(); 330 } 331 332 @Override 333 public void startPrinterStateTracking(PrinterId printerId) { 334 mHandler.obtainMessage(ServiceHandler.MSG_START_PRINTER_STATE_TRACKING, 335 printerId).sendToTarget(); 336 } 337 338 @Override 339 public void stopPrinterStateTracking(PrinterId printerId) { 340 mHandler.obtainMessage(ServiceHandler.MSG_STOP_PRINTER_STATE_TRACKING, 341 printerId).sendToTarget(); 342 } 343 344 @Override 345 public void setClient(IPrintServiceClient client) { 346 mHandler.obtainMessage(ServiceHandler.MSG_SET_CLEINT, client) 347 .sendToTarget(); 348 } 349 350 @Override 351 public void requestCancelPrintJob(PrintJobInfo printJobInfo) { 352 mHandler.obtainMessage(ServiceHandler.MSG_ON_REQUEST_CANCEL_PRINTJOB, 353 printJobInfo).sendToTarget(); 354 } 355 356 @Override 357 public void onPrintJobQueued(PrintJobInfo printJobInfo) { 358 mHandler.obtainMessage(ServiceHandler.MSG_ON_PRINTJOB_QUEUED, 359 printJobInfo).sendToTarget(); 360 } 361 }; 362 } 363 364 private final class ServiceHandler extends Handler { 365 public static final int MSG_CREATE_PRINTER_DISCOVERY_SESSION = 1; 366 public static final int MSG_DESTROY_PRINTER_DISCOVERY_SESSION = 2; 367 public static final int MSG_START_PRINTER_DISCOVERY = 3; 368 public static final int MSG_STOP_PRINTER_DISCOVERY = 4; 369 public static final int MSG_VALIDATE_PRINTERS = 5; 370 public static final int MSG_START_PRINTER_STATE_TRACKING = 6; 371 public static final int MSG_STOP_PRINTER_STATE_TRACKING = 7; 372 public static final int MSG_ON_PRINTJOB_QUEUED = 8; 373 public static final int MSG_ON_REQUEST_CANCEL_PRINTJOB = 9; 374 public static final int MSG_SET_CLEINT = 10; 375 376 public ServiceHandler(Looper looper) { 377 super(looper, null, true); 378 } 379 380 @Override 381 @SuppressWarnings("unchecked") 382 public void handleMessage(Message message) { 383 final int action = message.what; 384 switch (action) { 385 case MSG_CREATE_PRINTER_DISCOVERY_SESSION: { 386 if (DEBUG) { 387 Log.i(LOG_TAG, "MSG_CREATE_PRINTER_DISCOVERY_SESSION " 388 + getPackageName()); 389 } 390 PrinterDiscoverySession session = onCreatePrinterDiscoverySession(); 391 if (session == null) { 392 throw new NullPointerException("session cannot be null"); 393 } 394 if (session.getId() == mLastSessionId) { 395 throw new IllegalStateException("cannot reuse session instances"); 396 } 397 mDiscoverySession = session; 398 mLastSessionId = session.getId(); 399 session.setObserver(mClient); 400 } break; 401 402 case MSG_DESTROY_PRINTER_DISCOVERY_SESSION: { 403 if (DEBUG) { 404 Log.i(LOG_TAG, "MSG_DESTROY_PRINTER_DISCOVERY_SESSION " 405 + getPackageName()); 406 } 407 if (mDiscoverySession != null) { 408 mDiscoverySession.destroy(); 409 mDiscoverySession = null; 410 } 411 } break; 412 413 case MSG_START_PRINTER_DISCOVERY: { 414 if (DEBUG) { 415 Log.i(LOG_TAG, "MSG_START_PRINTER_DISCOVERY " 416 + getPackageName()); 417 } 418 if (mDiscoverySession != null) { 419 List<PrinterId> priorityList = (ArrayList<PrinterId>) message.obj; 420 mDiscoverySession.startPrinterDiscovery(priorityList); 421 } 422 } break; 423 424 case MSG_STOP_PRINTER_DISCOVERY: { 425 if (DEBUG) { 426 Log.i(LOG_TAG, "MSG_STOP_PRINTER_DISCOVERY " 427 + getPackageName()); 428 } 429 if (mDiscoverySession != null) { 430 mDiscoverySession.stopPrinterDiscovery(); 431 } 432 } break; 433 434 case MSG_VALIDATE_PRINTERS: { 435 if (DEBUG) { 436 Log.i(LOG_TAG, "MSG_VALIDATE_PRINTERS " 437 + getPackageName()); 438 } 439 if (mDiscoverySession != null) { 440 List<PrinterId> printerIds = (List<PrinterId>) message.obj; 441 mDiscoverySession.validatePrinters(printerIds); 442 } 443 } break; 444 445 case MSG_START_PRINTER_STATE_TRACKING: { 446 if (DEBUG) { 447 Log.i(LOG_TAG, "MSG_START_PRINTER_STATE_TRACKING " 448 + getPackageName()); 449 } 450 if (mDiscoverySession != null) { 451 PrinterId printerId = (PrinterId) message.obj; 452 mDiscoverySession.startPrinterStateTracking(printerId); 453 } 454 } break; 455 456 case MSG_STOP_PRINTER_STATE_TRACKING: { 457 if (DEBUG) { 458 Log.i(LOG_TAG, "MSG_STOP_PRINTER_STATE_TRACKING " 459 + getPackageName()); 460 } 461 if (mDiscoverySession != null) { 462 PrinterId printerId = (PrinterId) message.obj; 463 mDiscoverySession.stopPrinterStateTracking(printerId); 464 } 465 } break; 466 467 case MSG_ON_REQUEST_CANCEL_PRINTJOB: { 468 if (DEBUG) { 469 Log.i(LOG_TAG, "MSG_ON_REQUEST_CANCEL_PRINTJOB " 470 + getPackageName()); 471 } 472 PrintJobInfo printJobInfo = (PrintJobInfo) message.obj; 473 onRequestCancelPrintJob(new PrintJob(printJobInfo, mClient)); 474 } break; 475 476 case MSG_ON_PRINTJOB_QUEUED: { 477 if (DEBUG) { 478 Log.i(LOG_TAG, "MSG_ON_PRINTJOB_QUEUED " 479 + getPackageName()); 480 } 481 PrintJobInfo printJobInfo = (PrintJobInfo) message.obj; 482 if (DEBUG) { 483 Log.i(LOG_TAG, "Queued: " + printJobInfo); 484 } 485 onPrintJobQueued(new PrintJob(printJobInfo, mClient)); 486 } break; 487 488 case MSG_SET_CLEINT: { 489 if (DEBUG) { 490 Log.i(LOG_TAG, "MSG_SET_CLEINT " 491 + getPackageName()); 492 } 493 mClient = (IPrintServiceClient) message.obj; 494 if (mClient != null) { 495 onConnected(); 496 } else { 497 onDisconnected(); 498 } 499 } break; 500 501 default: { 502 throw new IllegalArgumentException("Unknown message: " + action); 503 } 504 } 505 } 506 } 507} 508