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.R; 20import android.app.Service; 21import android.content.ComponentName; 22import android.content.Context; 23import android.content.Intent; 24import android.os.Handler; 25import android.os.IBinder; 26import android.os.Looper; 27import android.os.Message; 28import android.os.RemoteException; 29import android.print.PrintJobInfo; 30import android.print.PrinterId; 31import android.util.Log; 32 33import java.util.ArrayList; 34import java.util.Collections; 35import java.util.List; 36 37/** 38 * <p> 39 * This is the base class for implementing print services. A print service knows 40 * how to discover and interact one or more printers via one or more protocols. 41 * </p> 42 * <h3>Printer discovery</h3> 43 * <p> 44 * A print service is responsible for discovering printers, adding discovered printers, 45 * removing added printers, and updating added printers. When the system is interested 46 * in printers managed by your service it will call {@link 47 * #onCreatePrinterDiscoverySession()} from which you must return a new {@link 48 * PrinterDiscoverySession} instance. The returned session encapsulates the interaction 49 * between the system and your service during printer discovery. For description of this 50 * interaction refer to the documentation for {@link PrinterDiscoverySession}. 51 * </p> 52 * <p> 53 * For every printer discovery session all printers have to be added since system does 54 * not retain printers across sessions. Hence, each printer known to this print service 55 * should be added only once during a discovery session. Only an already added printer 56 * can be removed or updated. Removed printers can be added again. 57 * </p> 58 * <h3>Print jobs</h3> 59 * <p> 60 * When a new print job targeted to a printer managed by this print service is is queued, 61 * i.e. ready for processing by the print service, you will receive a call to {@link 62 * #onPrintJobQueued(PrintJob)}. The print service may handle the print job immediately 63 * or schedule that for an appropriate time in the future. The list of all active print 64 * jobs for this service is obtained by calling {@link #getActivePrintJobs()}. Active 65 * print jobs are ones that are queued or started. 66 * </p> 67 * <p> 68 * A print service is responsible for setting a print job's state as appropriate 69 * while processing it. Initially, a print job is queued, i.e. {@link PrintJob#isQueued() 70 * PrintJob.isQueued()} returns true, which means that the document to be printed is 71 * spooled by the system and the print service can begin processing it. You can obtain 72 * the printed document by calling {@link PrintJob#getDocument() PrintJob.getDocument()} 73 * whose data is accessed via {@link PrintDocument#getData() PrintDocument.getData()}. 74 * After the print service starts printing the data it should set the print job's 75 * state to started by calling {@link PrintJob#start()} after which 76 * {@link PrintJob#isStarted() PrintJob.isStarted()} would return true. Upon successful 77 * completion, the print job should be marked as completed by calling {@link 78 * PrintJob#complete() PrintJob.complete()} after which {@link PrintJob#isCompleted() 79 * PrintJob.isCompleted()} would return true. In case of a failure, the print job should 80 * be marked as failed by calling {@link PrintJob#fail(String) PrintJob.fail( 81 * String)} after which {@link PrintJob#isFailed() PrintJob.isFailed()} would 82 * return true. 83 * </p> 84 * <p> 85 * If a print job is queued or started and the user requests to cancel it, the print 86 * service will receive a call to {@link #onRequestCancelPrintJob(PrintJob)} which 87 * requests from the service to do best effort in canceling the job. In case the job 88 * is successfully canceled, its state has to be marked as cancelled by calling {@link 89 * PrintJob#cancel() PrintJob.cancel()} after which {@link PrintJob#isCancelled() 90 * PrintJob.isCacnelled()} would return true. 91 * </p> 92 * <h3>Lifecycle</h3> 93 * <p> 94 * The lifecycle of a print service is managed exclusively by the system and follows 95 * the established service lifecycle. Additionally, starting or stopping a print service 96 * is triggered exclusively by an explicit user action through enabling or disabling it 97 * in the device settings. After the system binds to a print service, it calls {@link 98 * #onConnected()}. This method can be overriden by clients to perform post binding setup. 99 * Also after the system unbinds from a print service, it calls {@link #onDisconnected()}. 100 * This method can be overriden by clients to perform post unbinding cleanup. Your should 101 * not do any work after the system disconnected from your print service since the 102 * service can be killed at any time to reclaim memory. The system will not disconnect 103 * from a print service if there are active print jobs for the printers managed by it. 104 * </p> 105 * <h3>Declaration</h3> 106 * <p> 107 * A print service is declared as any other service in an AndroidManifest.xml but it must 108 * also specify that it handles the {@link android.content.Intent} with action {@link 109 * #SERVICE_INTERFACE android.printservice.PrintService}. Failure to declare this intent 110 * will cause the system to ignore the print service. Additionally, a print service must 111 * request the {@link android.Manifest.permission#BIND_PRINT_SERVICE 112 * android.permission.BIND_PRINT_SERVICE} permission to ensure that only the system can 113 * bind to it. Failure to declare this intent will cause the system to ignore the print 114 * service. Following is an example declaration: 115 * </p> 116 * <pre> 117 * <service android:name=".MyPrintService" 118 * android:permission="android.permission.BIND_PRINT_SERVICE"> 119 * <intent-filter> 120 * <action android:name="android.printservice.PrintService" /> 121 * </intent-filter> 122 * . . . 123 * </service> 124 * </pre> 125 * <h3>Configuration</h3> 126 * <p> 127 * A print service can be configured by specifying an optional settings activity which 128 * exposes service specific settings, an optional add printers activity which is used for 129 * manual addition of printers, vendor name ,etc. It is a responsibility of the system 130 * to launch the settings and add printers activities when appropriate. 131 * </p> 132 * <p> 133 * A print service is configured by providing a {@link #SERVICE_META_DATA meta-data} 134 * entry in the manifest when declaring the service. A service declaration with a meta-data 135 * tag is presented below: 136 * <pre> <service android:name=".MyPrintService" 137 * android:permission="android.permission.BIND_PRINT_SERVICE"> 138 * <intent-filter> 139 * <action android:name="android.printservice.PrintService" /> 140 * </intent-filter> 141 * <meta-data android:name="android.printservice" android:resource="@xml/printservice" /> 142 * </service></pre> 143 * </p> 144 * <p> 145 * For more details for how to configure your print service via the meta-data refer to 146 * {@link #SERVICE_META_DATA} and <code><{@link android.R.styleable#PrintService 147 * print-service}></code>. 148 * </p> 149 * <p> 150 * <strong>Note: </strong> All callbacks in this class are executed on the main 151 * application thread. You should also invoke any method of this class on the main 152 * application thread. 153 * </p> 154 */ 155public abstract class PrintService extends Service { 156 157 private static final String LOG_TAG = "PrintService"; 158 159 private static final boolean DEBUG = false; 160 161 /** 162 * The {@link Intent} action that must be declared as handled by a service 163 * in its manifest for the system to recognize it as a print service. 164 */ 165 public static final String SERVICE_INTERFACE = "android.printservice.PrintService"; 166 167 /** 168 * Name under which a {@link PrintService} component publishes additional information 169 * about itself. This meta-data must reference a XML resource containing a <code> 170 * <{@link android.R.styleable#PrintService print-service}></code> tag. This is 171 * a sample XML file configuring a print service: 172 * <pre> <print-service 173 * android:vendor="SomeVendor" 174 * android:settingsActivity="foo.bar.MySettingsActivity" 175 * andorid:addPrintersActivity="foo.bar.MyAddPrintersActivity." 176 * . . . 177 * /></pre> 178 * <p> 179 * For detailed configuration options that can be specified via the meta-data 180 * refer to {@link android.R.styleable#PrintService android.R.styleable.PrintService}. 181 * </p> 182 * <p> 183 * If you declare a settings or add a printers activity, they have to be exported, 184 * by setting the {@link android.R.attr#exported} activity attribute to <code>true 185 * </code>. Also in case you want only the system to be able to start any of these 186 * activities you can specify that they request the android.permission 187 * .START_PRINT_SERVICE_CONFIG_ACTIVITY permission by setting the 188 * {@link android.R.attr#permission} activity attribute. 189 * </p> 190 */ 191 public static final String SERVICE_META_DATA = "android.printservice"; 192 193 /** 194 * If you declared an optional activity with advanced print options via the 195 * {@link R.attr#advancedPrintOptionsActivity advancedPrintOptionsActivity} 196 * attribute, this extra is used to pass in the currently constructed {@link 197 * PrintJobInfo} to your activity allowing you to modify it. After you are 198 * done, you must return the modified {@link PrintJobInfo} via the same extra. 199 * <p> 200 * You cannot modify the passed in {@link PrintJobInfo} directly, rather you 201 * should build another one using the {@link PrintJobInfo.Builder} class. You 202 * can specify any standard properties and add advanced, printer specific, 203 * ones via {@link PrintJobInfo.Builder#putAdvancedOption(String, String) 204 * PrintJobInfo.Builder#putAdvancedOption(String, String)} and {@link 205 * PrintJobInfo.Builder#putAdvancedOption(String, int) 206 * PrintJobInfo.Builder#putAdvancedOption(String, int)}. The advanced options 207 * are not interpreted by the system, they will not be visible to applications, 208 * and can only be accessed by your print service via {@link 209 * PrintJob#getAdvancedStringOption(String) PrintJob.getAdvancedStringOption(String)} 210 * and {@link PrintJob#getAdvancedIntOption(String) PrintJob.getAdvancedIntOption(String)}. 211 * </p> 212 */ 213 public static final String EXTRA_PRINT_JOB_INFO = "android.intent.extra.print.PRINT_JOB_INFO"; 214 215 private Handler mHandler; 216 217 private IPrintServiceClient mClient; 218 219 private int mLastSessionId = -1; 220 221 private PrinterDiscoverySession mDiscoverySession; 222 223 @Override 224 protected final void attachBaseContext(Context base) { 225 super.attachBaseContext(base); 226 mHandler = new ServiceHandler(base.getMainLooper()); 227 } 228 229 /** 230 * The system has connected to this service. 231 */ 232 protected void onConnected() { 233 /* do nothing */ 234 } 235 236 /** 237 * The system has disconnected from this service. 238 */ 239 protected void onDisconnected() { 240 /* do nothing */ 241 } 242 243 /** 244 * Callback asking you to create a new {@link PrinterDiscoverySession}. 245 * 246 * @see PrinterDiscoverySession 247 */ 248 protected abstract PrinterDiscoverySession onCreatePrinterDiscoverySession(); 249 250 /** 251 * Called when cancellation of a print job is requested. The service 252 * should do best effort to fulfill the request. After the cancellation 253 * is performed, the print job should be marked as cancelled state by 254 * calling {@link PrintJob#cancel()}. 255 * 256 * @param printJob The print job to cancel. 257 * 258 * @see PrintJob#cancel() PrintJob.cancel() 259 * @see PrintJob#isCancelled() PrintJob.isCancelled() 260 */ 261 protected abstract void onRequestCancelPrintJob(PrintJob printJob); 262 263 /** 264 * Called when there is a queued print job for one of the printers 265 * managed by this print service. 266 * 267 * @param printJob The new queued print job. 268 * 269 * @see PrintJob#isQueued() PrintJob.isQueued() 270 * @see #getActivePrintJobs() 271 */ 272 protected abstract void onPrintJobQueued(PrintJob printJob); 273 274 /** 275 * Gets the active print jobs for the printers managed by this service. 276 * Active print jobs are ones that are not in a final state, i.e. whose 277 * state is queued or started. 278 * 279 * @return The active print jobs. 280 * 281 * @see PrintJob#isQueued() PrintJob.isQueued() 282 * @see PrintJob#isStarted() PrintJob.isStarted() 283 */ 284 public final List<PrintJob> getActivePrintJobs() { 285 throwIfNotCalledOnMainThread(); 286 if (mClient == null) { 287 return Collections.emptyList(); 288 } 289 try { 290 List<PrintJob> printJobs = null; 291 List<PrintJobInfo> printJobInfos = mClient.getPrintJobInfos(); 292 if (printJobInfos != null) { 293 final int printJobInfoCount = printJobInfos.size(); 294 printJobs = new ArrayList<PrintJob>(printJobInfoCount); 295 for (int i = 0; i < printJobInfoCount; i++) { 296 printJobs.add(new PrintJob(printJobInfos.get(i), mClient)); 297 } 298 } 299 if (printJobs != null) { 300 return printJobs; 301 } 302 } catch (RemoteException re) { 303 Log.e(LOG_TAG, "Error calling getPrintJobs()", re); 304 } 305 return Collections.emptyList(); 306 } 307 308 /** 309 * Generates a global printer id given the printer's locally unique one. 310 * 311 * @param localId A locally unique id in the context of your print service. 312 * @return Global printer id. 313 */ 314 public final PrinterId generatePrinterId(String localId) { 315 throwIfNotCalledOnMainThread(); 316 return new PrinterId(new ComponentName(getPackageName(), 317 getClass().getName()), localId); 318 } 319 320 static void throwIfNotCalledOnMainThread() { 321 if (!Looper.getMainLooper().isCurrentThread()) { 322 throw new IllegalAccessError("must be called from the main thread"); 323 } 324 } 325 326 @Override 327 public final IBinder onBind(Intent intent) { 328 return new IPrintService.Stub() { 329 @Override 330 public void createPrinterDiscoverySession() { 331 mHandler.sendEmptyMessage(ServiceHandler.MSG_CREATE_PRINTER_DISCOVERY_SESSION); 332 } 333 334 @Override 335 public void destroyPrinterDiscoverySession() { 336 mHandler.sendEmptyMessage(ServiceHandler.MSG_DESTROY_PRINTER_DISCOVERY_SESSION); 337 } 338 339 public void startPrinterDiscovery(List<PrinterId> priorityList) { 340 mHandler.obtainMessage(ServiceHandler.MSG_START_PRINTER_DISCOVERY, 341 priorityList).sendToTarget(); 342 } 343 344 @Override 345 public void stopPrinterDiscovery() { 346 mHandler.sendEmptyMessage(ServiceHandler.MSG_STOP_PRINTER_DISCOVERY); 347 } 348 349 @Override 350 public void validatePrinters(List<PrinterId> printerIds) { 351 mHandler.obtainMessage(ServiceHandler.MSG_VALIDATE_PRINTERS, 352 printerIds).sendToTarget(); 353 } 354 355 @Override 356 public void startPrinterStateTracking(PrinterId printerId) { 357 mHandler.obtainMessage(ServiceHandler.MSG_START_PRINTER_STATE_TRACKING, 358 printerId).sendToTarget(); 359 } 360 361 @Override 362 public void stopPrinterStateTracking(PrinterId printerId) { 363 mHandler.obtainMessage(ServiceHandler.MSG_STOP_PRINTER_STATE_TRACKING, 364 printerId).sendToTarget(); 365 } 366 367 @Override 368 public void setClient(IPrintServiceClient client) { 369 mHandler.obtainMessage(ServiceHandler.MSG_SET_CLEINT, client) 370 .sendToTarget(); 371 } 372 373 @Override 374 public void requestCancelPrintJob(PrintJobInfo printJobInfo) { 375 mHandler.obtainMessage(ServiceHandler.MSG_ON_REQUEST_CANCEL_PRINTJOB, 376 printJobInfo).sendToTarget(); 377 } 378 379 @Override 380 public void onPrintJobQueued(PrintJobInfo printJobInfo) { 381 mHandler.obtainMessage(ServiceHandler.MSG_ON_PRINTJOB_QUEUED, 382 printJobInfo).sendToTarget(); 383 } 384 }; 385 } 386 387 private final class ServiceHandler extends Handler { 388 public static final int MSG_CREATE_PRINTER_DISCOVERY_SESSION = 1; 389 public static final int MSG_DESTROY_PRINTER_DISCOVERY_SESSION = 2; 390 public static final int MSG_START_PRINTER_DISCOVERY = 3; 391 public static final int MSG_STOP_PRINTER_DISCOVERY = 4; 392 public static final int MSG_VALIDATE_PRINTERS = 5; 393 public static final int MSG_START_PRINTER_STATE_TRACKING = 6; 394 public static final int MSG_STOP_PRINTER_STATE_TRACKING = 7; 395 public static final int MSG_ON_PRINTJOB_QUEUED = 8; 396 public static final int MSG_ON_REQUEST_CANCEL_PRINTJOB = 9; 397 public static final int MSG_SET_CLEINT = 10; 398 399 public ServiceHandler(Looper looper) { 400 super(looper, null, true); 401 } 402 403 @Override 404 @SuppressWarnings("unchecked") 405 public void handleMessage(Message message) { 406 final int action = message.what; 407 switch (action) { 408 case MSG_CREATE_PRINTER_DISCOVERY_SESSION: { 409 if (DEBUG) { 410 Log.i(LOG_TAG, "MSG_CREATE_PRINTER_DISCOVERY_SESSION " 411 + getPackageName()); 412 } 413 PrinterDiscoverySession session = onCreatePrinterDiscoverySession(); 414 if (session == null) { 415 throw new NullPointerException("session cannot be null"); 416 } 417 if (session.getId() == mLastSessionId) { 418 throw new IllegalStateException("cannot reuse session instances"); 419 } 420 mDiscoverySession = session; 421 mLastSessionId = session.getId(); 422 session.setObserver(mClient); 423 } break; 424 425 case MSG_DESTROY_PRINTER_DISCOVERY_SESSION: { 426 if (DEBUG) { 427 Log.i(LOG_TAG, "MSG_DESTROY_PRINTER_DISCOVERY_SESSION " 428 + getPackageName()); 429 } 430 if (mDiscoverySession != null) { 431 mDiscoverySession.destroy(); 432 mDiscoverySession = null; 433 } 434 } break; 435 436 case MSG_START_PRINTER_DISCOVERY: { 437 if (DEBUG) { 438 Log.i(LOG_TAG, "MSG_START_PRINTER_DISCOVERY " 439 + getPackageName()); 440 } 441 if (mDiscoverySession != null) { 442 List<PrinterId> priorityList = (ArrayList<PrinterId>) message.obj; 443 mDiscoverySession.startPrinterDiscovery(priorityList); 444 } 445 } break; 446 447 case MSG_STOP_PRINTER_DISCOVERY: { 448 if (DEBUG) { 449 Log.i(LOG_TAG, "MSG_STOP_PRINTER_DISCOVERY " 450 + getPackageName()); 451 } 452 if (mDiscoverySession != null) { 453 mDiscoverySession.stopPrinterDiscovery(); 454 } 455 } break; 456 457 case MSG_VALIDATE_PRINTERS: { 458 if (DEBUG) { 459 Log.i(LOG_TAG, "MSG_VALIDATE_PRINTERS " 460 + getPackageName()); 461 } 462 if (mDiscoverySession != null) { 463 List<PrinterId> printerIds = (List<PrinterId>) message.obj; 464 mDiscoverySession.validatePrinters(printerIds); 465 } 466 } break; 467 468 case MSG_START_PRINTER_STATE_TRACKING: { 469 if (DEBUG) { 470 Log.i(LOG_TAG, "MSG_START_PRINTER_STATE_TRACKING " 471 + getPackageName()); 472 } 473 if (mDiscoverySession != null) { 474 PrinterId printerId = (PrinterId) message.obj; 475 mDiscoverySession.startPrinterStateTracking(printerId); 476 } 477 } break; 478 479 case MSG_STOP_PRINTER_STATE_TRACKING: { 480 if (DEBUG) { 481 Log.i(LOG_TAG, "MSG_STOP_PRINTER_STATE_TRACKING " 482 + getPackageName()); 483 } 484 if (mDiscoverySession != null) { 485 PrinterId printerId = (PrinterId) message.obj; 486 mDiscoverySession.stopPrinterStateTracking(printerId); 487 } 488 } break; 489 490 case MSG_ON_REQUEST_CANCEL_PRINTJOB: { 491 if (DEBUG) { 492 Log.i(LOG_TAG, "MSG_ON_REQUEST_CANCEL_PRINTJOB " 493 + getPackageName()); 494 } 495 PrintJobInfo printJobInfo = (PrintJobInfo) message.obj; 496 onRequestCancelPrintJob(new PrintJob(printJobInfo, mClient)); 497 } break; 498 499 case MSG_ON_PRINTJOB_QUEUED: { 500 if (DEBUG) { 501 Log.i(LOG_TAG, "MSG_ON_PRINTJOB_QUEUED " 502 + getPackageName()); 503 } 504 PrintJobInfo printJobInfo = (PrintJobInfo) message.obj; 505 if (DEBUG) { 506 Log.i(LOG_TAG, "Queued: " + printJobInfo); 507 } 508 onPrintJobQueued(new PrintJob(printJobInfo, mClient)); 509 } break; 510 511 case MSG_SET_CLEINT: { 512 if (DEBUG) { 513 Log.i(LOG_TAG, "MSG_SET_CLEINT " 514 + getPackageName()); 515 } 516 mClient = (IPrintServiceClient) message.obj; 517 if (mClient != null) { 518 onConnected(); 519 } else { 520 onDisconnected(); 521 } 522 } break; 523 524 default: { 525 throw new IllegalArgumentException("Unknown message: " + action); 526 } 527 } 528 } 529 } 530} 531