1 /* 2 * Copyright (C) 2006 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 17 package android.app; 18 19 import android.annotation.IntDef; 20 import android.annotation.Nullable; 21 import android.content.ComponentCallbacks2; 22 import android.content.ComponentName; 23 import android.content.Intent; 24 import android.content.ContextWrapper; 25 import android.content.Context; 26 import android.content.res.Configuration; 27 import android.os.Build; 28 import android.os.RemoteException; 29 import android.os.IBinder; 30 import android.util.Log; 31 32 import java.io.FileDescriptor; 33 import java.io.PrintWriter; 34 import java.lang.annotation.Retention; 35 import java.lang.annotation.RetentionPolicy; 36 37 /** 38 * A Service is an application component representing either an application's desire 39 * to perform a longer-running operation while not interacting with the user 40 * or to supply functionality for other applications to use. Each service 41 * class must have a corresponding 42 * {@link android.R.styleable#AndroidManifestService <service>} 43 * declaration in its package's <code>AndroidManifest.xml</code>. Services 44 * can be started with 45 * {@link android.content.Context#startService Context.startService()} and 46 * {@link android.content.Context#bindService Context.bindService()}. 47 * 48 * <p>Note that services, like other application objects, run in the main 49 * thread of their hosting process. This means that, if your service is going 50 * to do any CPU intensive (such as MP3 playback) or blocking (such as 51 * networking) operations, it should spawn its own thread in which to do that 52 * work. More information on this can be found in 53 * <a href="{@docRoot}guide/topics/fundamentals/processes-and-threads.html">Processes and 54 * Threads</a>. The {@link IntentService} class is available 55 * as a standard implementation of Service that has its own thread where it 56 * schedules its work to be done.</p> 57 * 58 * <p>Topics covered here: 59 * <ol> 60 * <li><a href="#WhatIsAService">What is a Service?</a> 61 * <li><a href="#ServiceLifecycle">Service Lifecycle</a> 62 * <li><a href="#Permissions">Permissions</a> 63 * <li><a href="#ProcessLifecycle">Process Lifecycle</a> 64 * <li><a href="#LocalServiceSample">Local Service Sample</a> 65 * <li><a href="#RemoteMessengerServiceSample">Remote Messenger Service Sample</a> 66 * </ol> 67 * 68 * <div class="special reference"> 69 * <h3>Developer Guides</h3> 70 * <p>For a detailed discussion about how to create services, read the 71 * <a href="{@docRoot}guide/topics/fundamentals/services.html">Services</a> developer guide.</p> 72 * </div> 73 * 74 * <a name="WhatIsAService"></a> 75 * <h3>What is a Service?</h3> 76 * 77 * <p>Most confusion about the Service class actually revolves around what 78 * it is <em>not</em>:</p> 79 * 80 * <ul> 81 * <li> A Service is <b>not</b> a separate process. The Service object itself 82 * does not imply it is running in its own process; unless otherwise specified, 83 * it runs in the same process as the application it is part of. 84 * <li> A Service is <b>not</b> a thread. It is not a means itself to do work off 85 * of the main thread (to avoid Application Not Responding errors). 86 * </ul> 87 * 88 * <p>Thus a Service itself is actually very simple, providing two main features:</p> 89 * 90 * <ul> 91 * <li>A facility for the application to tell the system <em>about</em> 92 * something it wants to be doing in the background (even when the user is not 93 * directly interacting with the application). This corresponds to calls to 94 * {@link android.content.Context#startService Context.startService()}, which 95 * ask the system to schedule work for the service, to be run until the service 96 * or someone else explicitly stop it. 97 * <li>A facility for an application to expose some of its functionality to 98 * other applications. This corresponds to calls to 99 * {@link android.content.Context#bindService Context.bindService()}, which 100 * allows a long-standing connection to be made to the service in order to 101 * interact with it. 102 * </ul> 103 * 104 * <p>When a Service component is actually created, for either of these reasons, 105 * all that the system actually does is instantiate the component 106 * and call its {@link #onCreate} and any other appropriate callbacks on the 107 * main thread. It is up to the Service to implement these with the appropriate 108 * behavior, such as creating a secondary thread in which it does its work.</p> 109 * 110 * <p>Note that because Service itself is so simple, you can make your 111 * interaction with it as simple or complicated as you want: from treating it 112 * as a local Java object that you make direct method calls on (as illustrated 113 * by <a href="#LocalServiceSample">Local Service Sample</a>), to providing 114 * a full remoteable interface using AIDL.</p> 115 * 116 * <a name="ServiceLifecycle"></a> 117 * <h3>Service Lifecycle</h3> 118 * 119 * <p>There are two reasons that a service can be run by the system. If someone 120 * calls {@link android.content.Context#startService Context.startService()} then the system will 121 * retrieve the service (creating it and calling its {@link #onCreate} method 122 * if needed) and then call its {@link #onStartCommand} method with the 123 * arguments supplied by the client. The service will at this point continue 124 * running until {@link android.content.Context#stopService Context.stopService()} or 125 * {@link #stopSelf()} is called. Note that multiple calls to 126 * Context.startService() do not nest (though they do result in multiple corresponding 127 * calls to onStartCommand()), so no matter how many times it is started a service 128 * will be stopped once Context.stopService() or stopSelf() is called; however, 129 * services can use their {@link #stopSelf(int)} method to ensure the service is 130 * not stopped until started intents have been processed. 131 * 132 * <p>For started services, there are two additional major modes of operation 133 * they can decide to run in, depending on the value they return from 134 * onStartCommand(): {@link #START_STICKY} is used for services that are 135 * explicitly started and stopped as needed, while {@link #START_NOT_STICKY} 136 * or {@link #START_REDELIVER_INTENT} are used for services that should only 137 * remain running while processing any commands sent to them. See the linked 138 * documentation for more detail on the semantics. 139 * 140 * <p>Clients can also use {@link android.content.Context#bindService Context.bindService()} to 141 * obtain a persistent connection to a service. This likewise creates the 142 * service if it is not already running (calling {@link #onCreate} while 143 * doing so), but does not call onStartCommand(). The client will receive the 144 * {@link android.os.IBinder} object that the service returns from its 145 * {@link #onBind} method, allowing the client to then make calls back 146 * to the service. The service will remain running as long as the connection 147 * is established (whether or not the client retains a reference on the 148 * service's IBinder). Usually the IBinder returned is for a complex 149 * interface that has been <a href="{@docRoot}guide/components/aidl.html">written 150 * in aidl</a>. 151 * 152 * <p>A service can be both started and have connections bound to it. In such 153 * a case, the system will keep the service running as long as either it is 154 * started <em>or</em> there are one or more connections to it with the 155 * {@link android.content.Context#BIND_AUTO_CREATE Context.BIND_AUTO_CREATE} 156 * flag. Once neither 157 * of these situations hold, the service's {@link #onDestroy} method is called 158 * and the service is effectively terminated. All cleanup (stopping threads, 159 * unregistering receivers) should be complete upon returning from onDestroy(). 160 * 161 * <a name="Permissions"></a> 162 * <h3>Permissions</h3> 163 * 164 * <p>Global access to a service can be enforced when it is declared in its 165 * manifest's {@link android.R.styleable#AndroidManifestService <service>} 166 * tag. By doing so, other applications will need to declare a corresponding 167 * {@link android.R.styleable#AndroidManifestUsesPermission <uses-permission>} 168 * element in their own manifest to be able to start, stop, or bind to 169 * the service. 170 * 171 * <p>As of {@link android.os.Build.VERSION_CODES#GINGERBREAD}, when using 172 * {@link Context#startService(Intent) Context.startService(Intent)}, you can 173 * also set {@link Intent#FLAG_GRANT_READ_URI_PERMISSION 174 * Intent.FLAG_GRANT_READ_URI_PERMISSION} and/or {@link Intent#FLAG_GRANT_WRITE_URI_PERMISSION 175 * Intent.FLAG_GRANT_WRITE_URI_PERMISSION} on the Intent. This will grant the 176 * Service temporary access to the specific URIs in the Intent. Access will 177 * remain until the Service has called {@link #stopSelf(int)} for that start 178 * command or a later one, or until the Service has been completely stopped. 179 * This works for granting access to the other apps that have not requested 180 * the permission protecting the Service, or even when the Service is not 181 * exported at all. 182 * 183 * <p>In addition, a service can protect individual IPC calls into it with 184 * permissions, by calling the 185 * {@link #checkCallingPermission} 186 * method before executing the implementation of that call. 187 * 188 * <p>See the <a href="{@docRoot}guide/topics/security/security.html">Security and Permissions</a> 189 * document for more information on permissions and security in general. 190 * 191 * <a name="ProcessLifecycle"></a> 192 * <h3>Process Lifecycle</h3> 193 * 194 * <p>The Android system will attempt to keep the process hosting a service 195 * around as long as the service has been started or has clients bound to it. 196 * When running low on memory and needing to kill existing processes, the 197 * priority of a process hosting the service will be the higher of the 198 * following possibilities: 199 * 200 * <ul> 201 * <li><p>If the service is currently executing code in its 202 * {@link #onCreate onCreate()}, {@link #onStartCommand onStartCommand()}, 203 * or {@link #onDestroy onDestroy()} methods, then the hosting process will 204 * be a foreground process to ensure this code can execute without 205 * being killed. 206 * <li><p>If the service has been started, then its hosting process is considered 207 * to be less important than any processes that are currently visible to the 208 * user on-screen, but more important than any process not visible. Because 209 * only a few processes are generally visible to the user, this means that 210 * the service should not be killed except in low memory conditions. However, since 211 * the user is not directly aware of a background service, in that state it <em>is</em> 212 * considered a valid candidate to kill, and you should be prepared for this to 213 * happen. In particular, long-running services will be increasingly likely to 214 * kill and are guaranteed to be killed (and restarted if appropriate) if they 215 * remain started long enough. 216 * <li><p>If there are clients bound to the service, then the service's hosting 217 * process is never less important than the most important client. That is, 218 * if one of its clients is visible to the user, then the service itself is 219 * considered to be visible. The way a client's importance impacts the service's 220 * importance can be adjusted through {@link Context#BIND_ABOVE_CLIENT}, 221 * {@link Context#BIND_ALLOW_OOM_MANAGEMENT}, {@link Context#BIND_WAIVE_PRIORITY}, 222 * {@link Context#BIND_IMPORTANT}, and {@link Context#BIND_ADJUST_WITH_ACTIVITY}. 223 * <li><p>A started service can use the {@link #startForeground(int, Notification)} 224 * API to put the service in a foreground state, where the system considers 225 * it to be something the user is actively aware of and thus not a candidate 226 * for killing when low on memory. (It is still theoretically possible for 227 * the service to be killed under extreme memory pressure from the current 228 * foreground application, but in practice this should not be a concern.) 229 * </ul> 230 * 231 * <p>Note this means that most of the time your service is running, it may 232 * be killed by the system if it is under heavy memory pressure. If this 233 * happens, the system will later try to restart the service. An important 234 * consequence of this is that if you implement {@link #onStartCommand onStartCommand()} 235 * to schedule work to be done asynchronously or in another thread, then you 236 * may want to use {@link #START_FLAG_REDELIVERY} to have the system 237 * re-deliver an Intent for you so that it does not get lost if your service 238 * is killed while processing it. 239 * 240 * <p>Other application components running in the same process as the service 241 * (such as an {@link android.app.Activity}) can, of course, increase the 242 * importance of the overall 243 * process beyond just the importance of the service itself. 244 * 245 * <a name="LocalServiceSample"></a> 246 * <h3>Local Service Sample</h3> 247 * 248 * <p>One of the most common uses of a Service is as a secondary component 249 * running alongside other parts of an application, in the same process as 250 * the rest of the components. All components of an .apk run in the same 251 * process unless explicitly stated otherwise, so this is a typical situation. 252 * 253 * <p>When used in this way, by assuming the 254 * components are in the same process, you can greatly simplify the interaction 255 * between them: clients of the service can simply cast the IBinder they 256 * receive from it to a concrete class published by the service. 257 * 258 * <p>An example of this use of a Service is shown here. First is the Service 259 * itself, publishing a custom class when bound: 260 * 261 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/LocalService.java 262 * service} 263 * 264 * <p>With that done, one can now write client code that directly accesses the 265 * running service, such as: 266 * 267 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/LocalServiceActivities.java 268 * bind} 269 * 270 * <a name="RemoteMessengerServiceSample"></a> 271 * <h3>Remote Messenger Service Sample</h3> 272 * 273 * <p>If you need to be able to write a Service that can perform complicated 274 * communication with clients in remote processes (beyond simply the use of 275 * {@link Context#startService(Intent) Context.startService} to send 276 * commands to it), then you can use the {@link android.os.Messenger} class 277 * instead of writing full AIDL files. 278 * 279 * <p>An example of a Service that uses Messenger as its client interface 280 * is shown here. First is the Service itself, publishing a Messenger to 281 * an internal Handler when bound: 282 * 283 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/MessengerService.java 284 * service} 285 * 286 * <p>If we want to make this service run in a remote process (instead of the 287 * standard one for its .apk), we can use <code>android:process</code> in its 288 * manifest tag to specify one: 289 * 290 * {@sample development/samples/ApiDemos/AndroidManifest.xml remote_service_declaration} 291 * 292 * <p>Note that the name "remote" chosen here is arbitrary, and you can use 293 * other names if you want additional processes. The ':' prefix appends the 294 * name to your package's standard process name. 295 * 296 * <p>With that done, clients can now bind to the service and send messages 297 * to it. Note that this allows clients to register with it to receive 298 * messages back as well: 299 * 300 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/MessengerServiceActivities.java 301 * bind} 302 */ 303 public abstract class Service extends ContextWrapper implements ComponentCallbacks2 { 304 private static final String TAG = "Service"; 305 306 /** 307 * Flag for {@link #stopForeground(int)}: if set, the notification previously provided 308 * to {@link #startForeground} will be removed. Otherwise it will remain 309 * until a later call (to {@link #startForeground(int, Notification)} or 310 * {@link #stopForeground(int)} removes it, or the service is destroyed. 311 */ 312 public static final int STOP_FOREGROUND_REMOVE = 1<<0; 313 314 /** 315 * Flag for {@link #stopForeground(int)}: if set, the notification previously provided 316 * to {@link #startForeground} will be detached from the service. Only makes sense 317 * when {@link #STOP_FOREGROUND_REMOVE} is <b>not</b> set -- in this case, the notification 318 * will remain shown, but be completely detached from the service and so no longer changed 319 * except through direct calls to the notification manager. 320 */ 321 public static final int STOP_FOREGROUND_DETACH = 1<<1; 322 323 /** @hide */ 324 @IntDef(flag = true, prefix = { "STOP_FOREGROUND_" }, value = { 325 STOP_FOREGROUND_REMOVE, 326 STOP_FOREGROUND_DETACH 327 }) 328 @Retention(RetentionPolicy.SOURCE) 329 public @interface StopForegroundFlags {} 330 Service()331 public Service() { 332 super(null); 333 } 334 335 /** Return the application that owns this service. */ getApplication()336 public final Application getApplication() { 337 return mApplication; 338 } 339 340 /** 341 * Called by the system when the service is first created. Do not call this method directly. 342 */ onCreate()343 public void onCreate() { 344 } 345 346 /** 347 * @deprecated Implement {@link #onStartCommand(Intent, int, int)} instead. 348 */ 349 @Deprecated onStart(Intent intent, int startId)350 public void onStart(Intent intent, int startId) { 351 } 352 353 /** 354 * Bits returned by {@link #onStartCommand} describing how to continue 355 * the service if it is killed. May be {@link #START_STICKY}, 356 * {@link #START_NOT_STICKY}, {@link #START_REDELIVER_INTENT}, 357 * or {@link #START_STICKY_COMPATIBILITY}. 358 */ 359 public static final int START_CONTINUATION_MASK = 0xf; 360 361 /** 362 * Constant to return from {@link #onStartCommand}: compatibility 363 * version of {@link #START_STICKY} that does not guarantee that 364 * {@link #onStartCommand} will be called again after being killed. 365 */ 366 public static final int START_STICKY_COMPATIBILITY = 0; 367 368 /** 369 * Constant to return from {@link #onStartCommand}: if this service's 370 * process is killed while it is started (after returning from 371 * {@link #onStartCommand}), then leave it in the started state but 372 * don't retain this delivered intent. Later the system will try to 373 * re-create the service. Because it is in the started state, it will 374 * guarantee to call {@link #onStartCommand} after creating the new 375 * service instance; if there are not any pending start commands to be 376 * delivered to the service, it will be called with a null intent 377 * object, so you must take care to check for this. 378 * 379 * <p>This mode makes sense for things that will be explicitly started 380 * and stopped to run for arbitrary periods of time, such as a service 381 * performing background music playback. 382 */ 383 public static final int START_STICKY = 1; 384 385 /** 386 * Constant to return from {@link #onStartCommand}: if this service's 387 * process is killed while it is started (after returning from 388 * {@link #onStartCommand}), and there are no new start intents to 389 * deliver to it, then take the service out of the started state and 390 * don't recreate until a future explicit call to 391 * {@link Context#startService Context.startService(Intent)}. The 392 * service will not receive a {@link #onStartCommand(Intent, int, int)} 393 * call with a null Intent because it will not be re-started if there 394 * are no pending Intents to deliver. 395 * 396 * <p>This mode makes sense for things that want to do some work as a 397 * result of being started, but can be stopped when under memory pressure 398 * and will explicit start themselves again later to do more work. An 399 * example of such a service would be one that polls for data from 400 * a server: it could schedule an alarm to poll every N minutes by having 401 * the alarm start its service. When its {@link #onStartCommand} is 402 * called from the alarm, it schedules a new alarm for N minutes later, 403 * and spawns a thread to do its networking. If its process is killed 404 * while doing that check, the service will not be restarted until the 405 * alarm goes off. 406 */ 407 public static final int START_NOT_STICKY = 2; 408 409 /** 410 * Constant to return from {@link #onStartCommand}: if this service's 411 * process is killed while it is started (after returning from 412 * {@link #onStartCommand}), then it will be scheduled for a restart 413 * and the last delivered Intent re-delivered to it again via 414 * {@link #onStartCommand}. This Intent will remain scheduled for 415 * redelivery until the service calls {@link #stopSelf(int)} with the 416 * start ID provided to {@link #onStartCommand}. The 417 * service will not receive a {@link #onStartCommand(Intent, int, int)} 418 * call with a null Intent because it will will only be re-started if 419 * it is not finished processing all Intents sent to it (and any such 420 * pending events will be delivered at the point of restart). 421 */ 422 public static final int START_REDELIVER_INTENT = 3; 423 424 /** @hide */ 425 @IntDef(flag = false, prefix = { "START_" }, value = { 426 START_STICKY_COMPATIBILITY, 427 START_STICKY, 428 START_NOT_STICKY, 429 START_REDELIVER_INTENT, 430 }) 431 @Retention(RetentionPolicy.SOURCE) 432 public @interface StartResult {} 433 434 /** 435 * Special constant for reporting that we are done processing 436 * {@link #onTaskRemoved(Intent)}. 437 * @hide 438 */ 439 public static final int START_TASK_REMOVED_COMPLETE = 1000; 440 441 /** 442 * This flag is set in {@link #onStartCommand} if the Intent is a 443 * re-delivery of a previously delivered intent, because the service 444 * had previously returned {@link #START_REDELIVER_INTENT} but had been 445 * killed before calling {@link #stopSelf(int)} for that Intent. 446 */ 447 public static final int START_FLAG_REDELIVERY = 0x0001; 448 449 /** 450 * This flag is set in {@link #onStartCommand} if the Intent is a 451 * retry because the original attempt never got to or returned from 452 * {@link #onStartCommand(Intent, int, int)}. 453 */ 454 public static final int START_FLAG_RETRY = 0x0002; 455 456 /** @hide */ 457 @IntDef(flag = true, prefix = { "START_FLAG_" }, value = { 458 START_FLAG_REDELIVERY, 459 START_FLAG_RETRY, 460 }) 461 @Retention(RetentionPolicy.SOURCE) 462 public @interface StartArgFlags {} 463 464 465 /** 466 * Called by the system every time a client explicitly starts the service by calling 467 * {@link android.content.Context#startService}, providing the arguments it supplied and a 468 * unique integer token representing the start request. Do not call this method directly. 469 * 470 * <p>For backwards compatibility, the default implementation calls 471 * {@link #onStart} and returns either {@link #START_STICKY} 472 * or {@link #START_STICKY_COMPATIBILITY}. 473 * 474 * <p>If you need your application to run on platform versions prior to API 475 * level 5, you can use the following model to handle the older {@link #onStart} 476 * callback in that case. The <code>handleCommand</code> method is implemented by 477 * you as appropriate: 478 * 479 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/ForegroundService.java 480 * start_compatibility} 481 * 482 * <p class="caution">Note that the system calls this on your 483 * service's main thread. A service's main thread is the same 484 * thread where UI operations take place for Activities running in the 485 * same process. You should always avoid stalling the main 486 * thread's event loop. When doing long-running operations, 487 * network calls, or heavy disk I/O, you should kick off a new 488 * thread, or use {@link android.os.AsyncTask}.</p> 489 * 490 * @param intent The Intent supplied to {@link android.content.Context#startService}, 491 * as given. This may be null if the service is being restarted after 492 * its process has gone away, and it had previously returned anything 493 * except {@link #START_STICKY_COMPATIBILITY}. 494 * @param flags Additional data about this start request. 495 * @param startId A unique integer representing this specific request to 496 * start. Use with {@link #stopSelfResult(int)}. 497 * 498 * @return The return value indicates what semantics the system should 499 * use for the service's current started state. It may be one of the 500 * constants associated with the {@link #START_CONTINUATION_MASK} bits. 501 * 502 * @see #stopSelfResult(int) 503 */ onStartCommand(Intent intent, @StartArgFlags int flags, int startId)504 public @StartResult int onStartCommand(Intent intent, @StartArgFlags int flags, int startId) { 505 onStart(intent, startId); 506 return mStartCompatibility ? START_STICKY_COMPATIBILITY : START_STICKY; 507 } 508 509 /** 510 * Called by the system to notify a Service that it is no longer used and is being removed. The 511 * service should clean up any resources it holds (threads, registered 512 * receivers, etc) at this point. Upon return, there will be no more calls 513 * in to this Service object and it is effectively dead. Do not call this method directly. 514 */ onDestroy()515 public void onDestroy() { 516 } 517 onConfigurationChanged(Configuration newConfig)518 public void onConfigurationChanged(Configuration newConfig) { 519 } 520 onLowMemory()521 public void onLowMemory() { 522 } 523 onTrimMemory(int level)524 public void onTrimMemory(int level) { 525 } 526 527 /** 528 * Return the communication channel to the service. May return null if 529 * clients can not bind to the service. The returned 530 * {@link android.os.IBinder} is usually for a complex interface 531 * that has been <a href="{@docRoot}guide/components/aidl.html">described using 532 * aidl</a>. 533 * 534 * <p><em>Note that unlike other application components, calls on to the 535 * IBinder interface returned here may not happen on the main thread 536 * of the process</em>. More information about the main thread can be found in 537 * <a href="{@docRoot}guide/topics/fundamentals/processes-and-threads.html">Processes and 538 * Threads</a>.</p> 539 * 540 * @param intent The Intent that was used to bind to this service, 541 * as given to {@link android.content.Context#bindService 542 * Context.bindService}. Note that any extras that were included with 543 * the Intent at that point will <em>not</em> be seen here. 544 * 545 * @return Return an IBinder through which clients can call on to the 546 * service. 547 */ 548 @Nullable onBind(Intent intent)549 public abstract IBinder onBind(Intent intent); 550 551 /** 552 * Called when all clients have disconnected from a particular interface 553 * published by the service. The default implementation does nothing and 554 * returns false. 555 * 556 * @param intent The Intent that was used to bind to this service, 557 * as given to {@link android.content.Context#bindService 558 * Context.bindService}. Note that any extras that were included with 559 * the Intent at that point will <em>not</em> be seen here. 560 * 561 * @return Return true if you would like to have the service's 562 * {@link #onRebind} method later called when new clients bind to it. 563 */ onUnbind(Intent intent)564 public boolean onUnbind(Intent intent) { 565 return false; 566 } 567 568 /** 569 * Called when new clients have connected to the service, after it had 570 * previously been notified that all had disconnected in its 571 * {@link #onUnbind}. This will only be called if the implementation 572 * of {@link #onUnbind} was overridden to return true. 573 * 574 * @param intent The Intent that was used to bind to this service, 575 * as given to {@link android.content.Context#bindService 576 * Context.bindService}. Note that any extras that were included with 577 * the Intent at that point will <em>not</em> be seen here. 578 */ onRebind(Intent intent)579 public void onRebind(Intent intent) { 580 } 581 582 /** 583 * This is called if the service is currently running and the user has 584 * removed a task that comes from the service's application. If you have 585 * set {@link android.content.pm.ServiceInfo#FLAG_STOP_WITH_TASK ServiceInfo.FLAG_STOP_WITH_TASK} 586 * then you will not receive this callback; instead, the service will simply 587 * be stopped. 588 * 589 * @param rootIntent The original root Intent that was used to launch 590 * the task that is being removed. 591 */ onTaskRemoved(Intent rootIntent)592 public void onTaskRemoved(Intent rootIntent) { 593 } 594 595 /** 596 * Stop the service, if it was previously started. This is the same as 597 * calling {@link android.content.Context#stopService} for this particular service. 598 * 599 * @see #stopSelfResult(int) 600 */ stopSelf()601 public final void stopSelf() { 602 stopSelf(-1); 603 } 604 605 /** 606 * Old version of {@link #stopSelfResult} that doesn't return a result. 607 * 608 * @see #stopSelfResult 609 */ stopSelf(int startId)610 public final void stopSelf(int startId) { 611 if (mActivityManager == null) { 612 return; 613 } 614 try { 615 mActivityManager.stopServiceToken( 616 new ComponentName(this, mClassName), mToken, startId); 617 } catch (RemoteException ex) { 618 } 619 } 620 621 /** 622 * Stop the service if the most recent time it was started was 623 * <var>startId</var>. This is the same as calling {@link 624 * android.content.Context#stopService} for this particular service but allows you to 625 * safely avoid stopping if there is a start request from a client that you 626 * haven't yet seen in {@link #onStart}. 627 * 628 * <p><em>Be careful about ordering of your calls to this function.</em>. 629 * If you call this function with the most-recently received ID before 630 * you have called it for previously received IDs, the service will be 631 * immediately stopped anyway. If you may end up processing IDs out 632 * of order (such as by dispatching them on separate threads), then you 633 * are responsible for stopping them in the same order you received them.</p> 634 * 635 * @param startId The most recent start identifier received in {@link 636 * #onStart}. 637 * @return Returns true if the startId matches the last start request 638 * and the service will be stopped, else false. 639 * 640 * @see #stopSelf() 641 */ stopSelfResult(int startId)642 public final boolean stopSelfResult(int startId) { 643 if (mActivityManager == null) { 644 return false; 645 } 646 try { 647 return mActivityManager.stopServiceToken( 648 new ComponentName(this, mClassName), mToken, startId); 649 } catch (RemoteException ex) { 650 } 651 return false; 652 } 653 654 /** 655 * @deprecated This is a now a no-op, use 656 * {@link #startForeground(int, Notification)} instead. This method 657 * has been turned into a no-op rather than simply being deprecated 658 * because analysis of numerous poorly behaving devices has shown that 659 * increasingly often the trouble is being caused in part by applications 660 * that are abusing it. Thus, given a choice between introducing 661 * problems in existing applications using this API (by allowing them to 662 * be killed when they would like to avoid it), vs allowing the performance 663 * of the entire system to be decreased, this method was deemed less 664 * important. 665 * 666 * @hide 667 */ 668 @Deprecated setForeground(boolean isForeground)669 public final void setForeground(boolean isForeground) { 670 Log.w(TAG, "setForeground: ignoring old API call on " + getClass().getName()); 671 } 672 673 /** 674 * If your service is started (running through {@link Context#startService(Intent)}), then 675 * also make this service run in the foreground, supplying the ongoing 676 * notification to be shown to the user while in this state. 677 * By default started services are background, meaning that their process won't be given 678 * foreground CPU scheduling (unless something else in that process is foreground) and, 679 * if the system needs to kill them to reclaim more memory (such as to display a large page in a 680 * web browser), they can be killed without too much harm. You use 681 * {@link #startForeground} if killing your service would be disruptive to the user, such as 682 * if your service is performing background music playback, so the user 683 * would notice if their music stopped playing. 684 * 685 * <p>Note that calling this method does <em>not</em> put the service in the started state 686 * itself, even though the name sounds like it. You must always call 687 * {@link #startService(Intent)} first to tell the system it should keep the service running, 688 * and then use this method to tell it to keep it running harder.</p> 689 * 690 * @param id The identifier for this notification as per 691 * {@link NotificationManager#notify(int, Notification) 692 * NotificationManager.notify(int, Notification)}; must not be 0. 693 * @param notification The Notification to be displayed. 694 * 695 * @see #stopForeground(boolean) 696 */ startForeground(int id, Notification notification)697 public final void startForeground(int id, Notification notification) { 698 try { 699 mActivityManager.setServiceForeground( 700 new ComponentName(this, mClassName), mToken, id, 701 notification, 0); 702 } catch (RemoteException ex) { 703 } 704 } 705 706 /** 707 * Synonym for {@link #stopForeground(int)}. 708 * @param removeNotification If true, the {@link #STOP_FOREGROUND_REMOVE} flag 709 * will be supplied. 710 * @see #stopForeground(int) 711 * @see #startForeground(int, Notification) 712 */ stopForeground(boolean removeNotification)713 public final void stopForeground(boolean removeNotification) { 714 stopForeground(removeNotification ? STOP_FOREGROUND_REMOVE : 0); 715 } 716 717 /** 718 * Remove this service from foreground state, allowing it to be killed if 719 * more memory is needed. This does not stop the service from running (for that 720 * you use {@link #stopSelf()} or related methods), just takes it out of the 721 * foreground state. 722 * 723 * @param flags additional behavior options. 724 * @see #startForeground(int, Notification) 725 */ stopForeground(@topForegroundFlags int flags)726 public final void stopForeground(@StopForegroundFlags int flags) { 727 try { 728 mActivityManager.setServiceForeground( 729 new ComponentName(this, mClassName), mToken, 0, null, flags); 730 } catch (RemoteException ex) { 731 } 732 } 733 734 /** 735 * Print the Service's state into the given stream. This gets invoked if 736 * you run "adb shell dumpsys activity service <yourservicename>" 737 * (note that for this command to work, the service must be running, and 738 * you must specify a fully-qualified service name). 739 * This is distinct from "dumpsys <servicename>", which only works for 740 * named system services and which invokes the {@link IBinder#dump} method 741 * on the {@link IBinder} interface registered with ServiceManager. 742 * 743 * @param fd The raw file descriptor that the dump is being sent to. 744 * @param writer The PrintWriter to which you should dump your state. This will be 745 * closed for you after you return. 746 * @param args additional arguments to the dump request. 747 */ dump(FileDescriptor fd, PrintWriter writer, String[] args)748 protected void dump(FileDescriptor fd, PrintWriter writer, String[] args) { 749 writer.println("nothing to dump"); 750 } 751 752 // ------------------ Internal API ------------------ 753 754 /** 755 * @hide 756 */ attach( Context context, ActivityThread thread, String className, IBinder token, Application application, Object activityManager)757 public final void attach( 758 Context context, 759 ActivityThread thread, String className, IBinder token, 760 Application application, Object activityManager) { 761 attachBaseContext(context); 762 mThread = thread; // NOTE: unused - remove? 763 mClassName = className; 764 mToken = token; 765 mApplication = application; 766 mActivityManager = (IActivityManager)activityManager; 767 mStartCompatibility = getApplicationInfo().targetSdkVersion 768 < Build.VERSION_CODES.ECLAIR; 769 } 770 771 /** 772 * @hide 773 * Clean up any references to avoid leaks. 774 */ 775 public final void detachAndCleanUp() { 776 mToken = null; 777 } 778 779 final String getClassName() { 780 return mClassName; 781 } 782 783 // set by the thread after the constructor and before onCreate(Bundle icicle) is called. 784 private ActivityThread mThread = null; 785 private String mClassName = null; 786 private IBinder mToken = null; 787 private Application mApplication = null; 788 private IActivityManager mActivityManager = null; 789 private boolean mStartCompatibility = false; 790 } 791