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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 static android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_MANIFEST;
20 
21 import android.annotation.IntDef;
22 import android.annotation.NonNull;
23 import android.annotation.Nullable;
24 import android.compat.annotation.UnsupportedAppUsage;
25 import android.content.ComponentCallbacks2;
26 import android.content.ComponentName;
27 import android.content.Context;
28 import android.content.ContextWrapper;
29 import android.content.Intent;
30 import android.content.pm.ServiceInfo;
31 import android.content.pm.ServiceInfo.ForegroundServiceType;
32 import android.content.res.Configuration;
33 import android.os.Build;
34 import android.os.IBinder;
35 import android.os.RemoteException;
36 import android.util.Log;
37 import android.view.contentcapture.ContentCaptureManager;
38 
39 import java.io.FileDescriptor;
40 import java.io.PrintWriter;
41 import java.lang.annotation.Retention;
42 import java.lang.annotation.RetentionPolicy;
43 
44 /**
45  * A Service is an application component representing either an application's desire
46  * to perform a longer-running operation while not interacting with the user
47  * or to supply functionality for other applications to use.  Each service
48  * class must have a corresponding
49  * {@link android.R.styleable#AndroidManifestService <service>}
50  * declaration in its package's <code>AndroidManifest.xml</code>.  Services
51  * can be started with
52  * {@link android.content.Context#startService Context.startService()} and
53  * {@link android.content.Context#bindService Context.bindService()}.
54  *
55  * <p>Note that services, like other application objects, run in the main
56  * thread of their hosting process.  This means that, if your service is going
57  * to do any CPU intensive (such as MP3 playback) or blocking (such as
58  * networking) operations, it should spawn its own thread in which to do that
59  * work.  More information on this can be found in
60  * <a href="{@docRoot}guide/topics/fundamentals/processes-and-threads.html">Processes and
61  * Threads</a>.  The {@link androidx.core.app.JobIntentService} class is available
62  * as a standard implementation of Service that has its own thread where it
63  * schedules its work to be done.</p>
64  *
65  * <p>Topics covered here:
66  * <ol>
67  * <li><a href="#WhatIsAService">What is a Service?</a>
68  * <li><a href="#ServiceLifecycle">Service Lifecycle</a>
69  * <li><a href="#Permissions">Permissions</a>
70  * <li><a href="#ProcessLifecycle">Process Lifecycle</a>
71  * <li><a href="#LocalServiceSample">Local Service Sample</a>
72  * <li><a href="#RemoteMessengerServiceSample">Remote Messenger Service Sample</a>
73  * </ol>
74  *
75  * <div class="special reference">
76  * <h3>Developer Guides</h3>
77  * <p>For a detailed discussion about how to create services, read the
78  * <a href="{@docRoot}guide/topics/fundamentals/services.html">Services</a> developer guide.</p>
79  * </div>
80  *
81  * <a name="WhatIsAService"></a>
82  * <h3>What is a Service?</h3>
83  *
84  * <p>Most confusion about the Service class actually revolves around what
85  * it is <em>not</em>:</p>
86  *
87  * <ul>
88  * <li> A Service is <b>not</b> a separate process.  The Service object itself
89  * does not imply it is running in its own process; unless otherwise specified,
90  * it runs in the same process as the application it is part of.
91  * <li> A Service is <b>not</b> a thread.  It is not a means itself to do work off
92  * of the main thread (to avoid Application Not Responding errors).
93  * </ul>
94  *
95  * <p>Thus a Service itself is actually very simple, providing two main features:</p>
96  *
97  * <ul>
98  * <li>A facility for the application to tell the system <em>about</em>
99  * something it wants to be doing in the background (even when the user is not
100  * directly interacting with the application).  This corresponds to calls to
101  * {@link android.content.Context#startService Context.startService()}, which
102  * ask the system to schedule work for the service, to be run until the service
103  * or someone else explicitly stop it.
104  * <li>A facility for an application to expose some of its functionality to
105  * other applications.  This corresponds to calls to
106  * {@link android.content.Context#bindService Context.bindService()}, which
107  * allows a long-standing connection to be made to the service in order to
108  * interact with it.
109  * </ul>
110  *
111  * <p>When a Service component is actually created, for either of these reasons,
112  * all that the system actually does is instantiate the component
113  * and call its {@link #onCreate} and any other appropriate callbacks on the
114  * main thread.  It is up to the Service to implement these with the appropriate
115  * behavior, such as creating a secondary thread in which it does its work.</p>
116  *
117  * <p>Note that because Service itself is so simple, you can make your
118  * interaction with it as simple or complicated as you want: from treating it
119  * as a local Java object that you make direct method calls on (as illustrated
120  * by <a href="#LocalServiceSample">Local Service Sample</a>), to providing
121  * a full remoteable interface using AIDL.</p>
122  *
123  * <a name="ServiceLifecycle"></a>
124  * <h3>Service Lifecycle</h3>
125  *
126  * <p>There are two reasons that a service can be run by the system.  If someone
127  * calls {@link android.content.Context#startService Context.startService()} then the system will
128  * retrieve the service (creating it and calling its {@link #onCreate} method
129  * if needed) and then call its {@link #onStartCommand} method with the
130  * arguments supplied by the client.  The service will at this point continue
131  * running until {@link android.content.Context#stopService Context.stopService()} or
132  * {@link #stopSelf()} is called.  Note that multiple calls to
133  * Context.startService() do not nest (though they do result in multiple corresponding
134  * calls to onStartCommand()), so no matter how many times it is started a service
135  * will be stopped once Context.stopService() or stopSelf() is called; however,
136  * services can use their {@link #stopSelf(int)} method to ensure the service is
137  * not stopped until started intents have been processed.
138  *
139  * <p>For started services, there are two additional major modes of operation
140  * they can decide to run in, depending on the value they return from
141  * onStartCommand(): {@link #START_STICKY} is used for services that are
142  * explicitly started and stopped as needed, while {@link #START_NOT_STICKY}
143  * or {@link #START_REDELIVER_INTENT} are used for services that should only
144  * remain running while processing any commands sent to them.  See the linked
145  * documentation for more detail on the semantics.
146  *
147  * <p>Clients can also use {@link android.content.Context#bindService Context.bindService()} to
148  * obtain a persistent connection to a service.  This likewise creates the
149  * service if it is not already running (calling {@link #onCreate} while
150  * doing so), but does not call onStartCommand().  The client will receive the
151  * {@link android.os.IBinder} object that the service returns from its
152  * {@link #onBind} method, allowing the client to then make calls back
153  * to the service.  The service will remain running as long as the connection
154  * is established (whether or not the client retains a reference on the
155  * service's IBinder).  Usually the IBinder returned is for a complex
156  * interface that has been <a href="{@docRoot}guide/components/aidl.html">written
157  * in aidl</a>.
158  *
159  * <p>A service can be both started and have connections bound to it.  In such
160  * a case, the system will keep the service running as long as either it is
161  * started <em>or</em> there are one or more connections to it with the
162  * {@link android.content.Context#BIND_AUTO_CREATE Context.BIND_AUTO_CREATE}
163  * flag.  Once neither
164  * of these situations hold, the service's {@link #onDestroy} method is called
165  * and the service is effectively terminated.  All cleanup (stopping threads,
166  * unregistering receivers) should be complete upon returning from onDestroy().
167  *
168  * <a name="Permissions"></a>
169  * <h3>Permissions</h3>
170  *
171  * <p>Global access to a service can be enforced when it is declared in its
172  * manifest's {@link android.R.styleable#AndroidManifestService &lt;service&gt;}
173  * tag.  By doing so, other applications will need to declare a corresponding
174  * {@link android.R.styleable#AndroidManifestUsesPermission &lt;uses-permission&gt;}
175  * element in their own manifest to be able to start, stop, or bind to
176  * the service.
177  *
178  * <p>As of {@link android.os.Build.VERSION_CODES#GINGERBREAD}, when using
179  * {@link Context#startService(Intent) Context.startService(Intent)}, you can
180  * also set {@link Intent#FLAG_GRANT_READ_URI_PERMISSION
181  * Intent.FLAG_GRANT_READ_URI_PERMISSION} and/or {@link Intent#FLAG_GRANT_WRITE_URI_PERMISSION
182  * Intent.FLAG_GRANT_WRITE_URI_PERMISSION} on the Intent.  This will grant the
183  * Service temporary access to the specific URIs in the Intent.  Access will
184  * remain until the Service has called {@link #stopSelf(int)} for that start
185  * command or a later one, or until the Service has been completely stopped.
186  * This works for granting access to the other apps that have not requested
187  * the permission protecting the Service, or even when the Service is not
188  * exported at all.
189  *
190  * <p>In addition, a service can protect individual IPC calls into it with
191  * permissions, by calling the
192  * {@link #checkCallingPermission}
193  * method before executing the implementation of that call.
194  *
195  * <p>See the <a href="{@docRoot}guide/topics/security/security.html">Security and Permissions</a>
196  * document for more information on permissions and security in general.
197  *
198  * <a name="ProcessLifecycle"></a>
199  * <h3>Process Lifecycle</h3>
200  *
201  * <p>The Android system will attempt to keep the process hosting a service
202  * around as long as the service has been started or has clients bound to it.
203  * When running low on memory and needing to kill existing processes, the
204  * priority of a process hosting the service will be the higher of the
205  * following possibilities:
206  *
207  * <ul>
208  * <li><p>If the service is currently executing code in its
209  * {@link #onCreate onCreate()}, {@link #onStartCommand onStartCommand()},
210  * or {@link #onDestroy onDestroy()} methods, then the hosting process will
211  * be a foreground process to ensure this code can execute without
212  * being killed.
213  * <li><p>If the service has been started, then its hosting process is considered
214  * to be less important than any processes that are currently visible to the
215  * user on-screen, but more important than any process not visible.  Because
216  * only a few processes are generally visible to the user, this means that
217  * the service should not be killed except in low memory conditions.  However, since
218  * the user is not directly aware of a background service, in that state it <em>is</em>
219  * considered a valid candidate to kill, and you should be prepared for this to
220  * happen.  In particular, long-running services will be increasingly likely to
221  * kill and are guaranteed to be killed (and restarted if appropriate) if they
222  * remain started long enough.
223  * <li><p>If there are clients bound to the service, then the service's hosting
224  * process is never less important than the most important client.  That is,
225  * if one of its clients is visible to the user, then the service itself is
226  * considered to be visible.  The way a client's importance impacts the service's
227  * importance can be adjusted through {@link Context#BIND_ABOVE_CLIENT},
228  * {@link Context#BIND_ALLOW_OOM_MANAGEMENT}, {@link Context#BIND_WAIVE_PRIORITY},
229  * {@link Context#BIND_IMPORTANT}, and {@link Context#BIND_ADJUST_WITH_ACTIVITY}.
230  * <li><p>A started service can use the {@link #startForeground(int, Notification)}
231  * API to put the service in a foreground state, where the system considers
232  * it to be something the user is actively aware of and thus not a candidate
233  * for killing when low on memory.  (It is still theoretically possible for
234  * the service to be killed under extreme memory pressure from the current
235  * foreground application, but in practice this should not be a concern.)
236  * </ul>
237  *
238  * <p>Note this means that most of the time your service is running, it may
239  * be killed by the system if it is under heavy memory pressure.  If this
240  * happens, the system will later try to restart the service.  An important
241  * consequence of this is that if you implement {@link #onStartCommand onStartCommand()}
242  * to schedule work to be done asynchronously or in another thread, then you
243  * may want to use {@link #START_FLAG_REDELIVERY} to have the system
244  * re-deliver an Intent for you so that it does not get lost if your service
245  * is killed while processing it.
246  *
247  * <p>Other application components running in the same process as the service
248  * (such as an {@link android.app.Activity}) can, of course, increase the
249  * importance of the overall
250  * process beyond just the importance of the service itself.
251  *
252  * <a name="LocalServiceSample"></a>
253  * <h3>Local Service Sample</h3>
254  *
255  * <p>One of the most common uses of a Service is as a secondary component
256  * running alongside other parts of an application, in the same process as
257  * the rest of the components.  All components of an .apk run in the same
258  * process unless explicitly stated otherwise, so this is a typical situation.
259  *
260  * <p>When used in this way, by assuming the
261  * components are in the same process, you can greatly simplify the interaction
262  * between them: clients of the service can simply cast the IBinder they
263  * receive from it to a concrete class published by the service.
264  *
265  * <p>An example of this use of a Service is shown here.  First is the Service
266  * itself, publishing a custom class when bound:
267  *
268  * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/LocalService.java
269  *      service}
270  *
271  * <p>With that done, one can now write client code that directly accesses the
272  * running service, such as:
273  *
274  * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/LocalServiceActivities.java
275  *      bind}
276  *
277  * <a name="RemoteMessengerServiceSample"></a>
278  * <h3>Remote Messenger Service Sample</h3>
279  *
280  * <p>If you need to be able to write a Service that can perform complicated
281  * communication with clients in remote processes (beyond simply the use of
282  * {@link Context#startService(Intent) Context.startService} to send
283  * commands to it), then you can use the {@link android.os.Messenger} class
284  * instead of writing full AIDL files.
285  *
286  * <p>An example of a Service that uses Messenger as its client interface
287  * is shown here.  First is the Service itself, publishing a Messenger to
288  * an internal Handler when bound:
289  *
290  * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/MessengerService.java
291  *      service}
292  *
293  * <p>If we want to make this service run in a remote process (instead of the
294  * standard one for its .apk), we can use <code>android:process</code> in its
295  * manifest tag to specify one:
296  *
297  * {@sample development/samples/ApiDemos/AndroidManifest.xml remote_service_declaration}
298  *
299  * <p>Note that the name "remote" chosen here is arbitrary, and you can use
300  * other names if you want additional processes.  The ':' prefix appends the
301  * name to your package's standard process name.
302  *
303  * <p>With that done, clients can now bind to the service and send messages
304  * to it.  Note that this allows clients to register with it to receive
305  * messages back as well:
306  *
307  * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/MessengerServiceActivities.java
308  *      bind}
309  */
310 public abstract class Service extends ContextWrapper implements ComponentCallbacks2,
311         ContentCaptureManager.ContentCaptureClient {
312     private static final String TAG = "Service";
313 
314     /**
315      * Flag for {@link #stopForeground(int)}: if set, the notification previously provided
316      * to {@link #startForeground} will be removed.  Otherwise it will remain
317      * until a later call (to {@link #startForeground(int, Notification)} or
318      * {@link #stopForeground(int)} removes it, or the service is destroyed.
319      */
320     public static final int STOP_FOREGROUND_REMOVE = 1<<0;
321 
322     /**
323      * Flag for {@link #stopForeground(int)}: if set, the notification previously provided
324      * to {@link #startForeground} will be detached from the service.  Only makes sense
325      * when {@link #STOP_FOREGROUND_REMOVE} is <b>not</b> set -- in this case, the notification
326      * will remain shown, but be completely detached from the service and so no longer changed
327      * except through direct calls to the notification manager.
328      */
329     public static final int STOP_FOREGROUND_DETACH = 1<<1;
330 
331     /** @hide */
332     @IntDef(flag = true, prefix = { "STOP_FOREGROUND_" }, value = {
333             STOP_FOREGROUND_REMOVE,
334             STOP_FOREGROUND_DETACH
335     })
336     @Retention(RetentionPolicy.SOURCE)
337     public @interface StopForegroundFlags {}
338 
Service()339     public Service() {
340         super(null);
341     }
342 
343     /** Return the application that owns this service. */
getApplication()344     public final Application getApplication() {
345         return mApplication;
346     }
347 
348     /**
349      * Called by the system when the service is first created.  Do not call this method directly.
350      */
onCreate()351     public void onCreate() {
352     }
353 
354     /**
355      * @deprecated Implement {@link #onStartCommand(Intent, int, int)} instead.
356      */
357     @Deprecated
onStart(Intent intent, int startId)358     public void onStart(Intent intent, int startId) {
359     }
360 
361     /**
362      * Bits returned by {@link #onStartCommand} describing how to continue
363      * the service if it is killed.  May be {@link #START_STICKY},
364      * {@link #START_NOT_STICKY}, {@link #START_REDELIVER_INTENT},
365      * or {@link #START_STICKY_COMPATIBILITY}.
366      */
367     public static final int START_CONTINUATION_MASK = 0xf;
368 
369     /**
370      * Constant to return from {@link #onStartCommand}: compatibility
371      * version of {@link #START_STICKY} that does not guarantee that
372      * {@link #onStartCommand} will be called again after being killed.
373      */
374     public static final int START_STICKY_COMPATIBILITY = 0;
375 
376     /**
377      * Constant to return from {@link #onStartCommand}: if this service's
378      * process is killed while it is started (after returning from
379      * {@link #onStartCommand}), then leave it in the started state but
380      * don't retain this delivered intent.  Later the system will try to
381      * re-create the service.  Because it is in the started state, it will
382      * guarantee to call {@link #onStartCommand} after creating the new
383      * service instance; if there are not any pending start commands to be
384      * delivered to the service, it will be called with a null intent
385      * object, so you must take care to check for this.
386      *
387      * <p>This mode makes sense for things that will be explicitly started
388      * and stopped to run for arbitrary periods of time, such as a service
389      * performing background music playback.
390      *
391      * <p>Since Android version {@link Build.VERSION_CODES#S}, apps
392      * targeting {@link Build.VERSION_CODES#S} or above are disallowed
393      * to start a foreground service from the background, but the restriction
394      * doesn't impact <em>restarts</em> of a sticky foreground service. However,
395      * when apps start a sticky foreground service from the background,
396      * the same restriction still applies.
397      */
398     public static final int START_STICKY = 1;
399 
400     /**
401      * Constant to return from {@link #onStartCommand}: if this service's
402      * process is killed while it is started (after returning from
403      * {@link #onStartCommand}), and there are no new start intents to
404      * deliver to it, then take the service out of the started state and
405      * don't recreate until a future explicit call to
406      * {@link Context#startService Context.startService(Intent)}.  The
407      * service will not receive a {@link #onStartCommand(Intent, int, int)}
408      * call with a null Intent because it will not be restarted if there
409      * are no pending Intents to deliver.
410      *
411      * <p>This mode makes sense for things that want to do some work as a
412      * result of being started, but can be stopped when under memory pressure
413      * and will explicit start themselves again later to do more work.  An
414      * example of such a service would be one that polls for data from
415      * a server: it could schedule an alarm to poll every N minutes by having
416      * the alarm start its service.  When its {@link #onStartCommand} is
417      * called from the alarm, it schedules a new alarm for N minutes later,
418      * and spawns a thread to do its networking.  If its process is killed
419      * while doing that check, the service will not be restarted until the
420      * alarm goes off.
421      */
422     public static final int START_NOT_STICKY = 2;
423 
424     /**
425      * Constant to return from {@link #onStartCommand}: if this service's
426      * process is killed while it is started (after returning from
427      * {@link #onStartCommand}), then it will be scheduled for a restart
428      * and the last delivered Intent re-delivered to it again via
429      * {@link #onStartCommand}.  This Intent will remain scheduled for
430      * redelivery until the service calls {@link #stopSelf(int)} with the
431      * start ID provided to {@link #onStartCommand}.  The
432      * service will not receive a {@link #onStartCommand(Intent, int, int)}
433      * call with a null Intent because it will only be restarted if
434      * it is not finished processing all Intents sent to it (and any such
435      * pending events will be delivered at the point of restart).
436      */
437     public static final int START_REDELIVER_INTENT = 3;
438 
439     /** @hide */
440     @IntDef(flag = false, prefix = { "START_" }, value = {
441             START_STICKY_COMPATIBILITY,
442             START_STICKY,
443             START_NOT_STICKY,
444             START_REDELIVER_INTENT,
445     })
446     @Retention(RetentionPolicy.SOURCE)
447     public @interface StartResult {}
448 
449     /**
450      * Special constant for reporting that we are done processing
451      * {@link #onTaskRemoved(Intent)}.
452      * @hide
453      */
454     public static final int START_TASK_REMOVED_COMPLETE = 1000;
455 
456     /**
457      * This flag is set in {@link #onStartCommand} if the Intent is a
458      * re-delivery of a previously delivered intent, because the service
459      * had previously returned {@link #START_REDELIVER_INTENT} but had been
460      * killed before calling {@link #stopSelf(int)} for that Intent.
461      */
462     public static final int START_FLAG_REDELIVERY = 0x0001;
463 
464     /**
465      * This flag is set in {@link #onStartCommand} if the Intent is a
466      * retry because the original attempt never got to or returned from
467      * {@link #onStartCommand(Intent, int, int)}.
468      */
469     public static final int START_FLAG_RETRY = 0x0002;
470 
471     /** @hide */
472     @IntDef(flag = true, prefix = { "START_FLAG_" }, value = {
473             START_FLAG_REDELIVERY,
474             START_FLAG_RETRY,
475     })
476     @Retention(RetentionPolicy.SOURCE)
477     public @interface StartArgFlags {}
478 
479 
480     /**
481      * Called by the system every time a client explicitly starts the service by calling
482      * {@link android.content.Context#startService}, providing the arguments it supplied and a
483      * unique integer token representing the start request.  Do not call this method directly.
484      *
485      * <p>For backwards compatibility, the default implementation calls
486      * {@link #onStart} and returns either {@link #START_STICKY}
487      * or {@link #START_STICKY_COMPATIBILITY}.
488      *
489      * <p class="caution">Note that the system calls this on your
490      * service's main thread.  A service's main thread is the same
491      * thread where UI operations take place for Activities running in the
492      * same process.  You should always avoid stalling the main
493      * thread's event loop.  When doing long-running operations,
494      * network calls, or heavy disk I/O, you should kick off a new
495      * thread, or use {@link android.os.AsyncTask}.</p>
496      *
497      * @param intent The Intent supplied to {@link android.content.Context#startService},
498      * as given.  This may be null if the service is being restarted after
499      * its process has gone away, and it had previously returned anything
500      * except {@link #START_STICKY_COMPATIBILITY}.
501      * @param flags Additional data about this start request.
502      * @param startId A unique integer representing this specific request to
503      * start.  Use with {@link #stopSelfResult(int)}.
504      *
505      * @return The return value indicates what semantics the system should
506      * use for the service's current started state.  It may be one of the
507      * constants associated with the {@link #START_CONTINUATION_MASK} bits.
508      *
509      * @see #stopSelfResult(int)
510      */
onStartCommand(Intent intent, @StartArgFlags int flags, int startId)511     public @StartResult int onStartCommand(Intent intent, @StartArgFlags int flags, int startId) {
512         onStart(intent, startId);
513         return mStartCompatibility ? START_STICKY_COMPATIBILITY : START_STICKY;
514     }
515 
516     /**
517      * Called by the system to notify a Service that it is no longer used and is being removed.  The
518      * service should clean up any resources it holds (threads, registered
519      * receivers, etc) at this point.  Upon return, there will be no more calls
520      * in to this Service object and it is effectively dead.  Do not call this method directly.
521      */
onDestroy()522     public void onDestroy() {
523     }
524 
onConfigurationChanged(Configuration newConfig)525     public void onConfigurationChanged(Configuration newConfig) {
526     }
527 
onLowMemory()528     public void onLowMemory() {
529     }
530 
onTrimMemory(int level)531     public void onTrimMemory(int level) {
532     }
533 
534     /**
535      * Return the communication channel to the service.  May return null if
536      * clients can not bind to the service.  The returned
537      * {@link android.os.IBinder} is usually for a complex interface
538      * that has been <a href="{@docRoot}guide/components/aidl.html">described using
539      * aidl</a>.
540      *
541      * <p><em>Note that unlike other application components, calls on to the
542      * IBinder interface returned here may not happen on the main thread
543      * of the process</em>.  More information about the main thread can be found in
544      * <a href="{@docRoot}guide/topics/fundamentals/processes-and-threads.html">Processes and
545      * Threads</a>.</p>
546      *
547      * @param intent The Intent that was used to bind to this service,
548      * as given to {@link android.content.Context#bindService
549      * Context.bindService}.  Note that any extras that were included with
550      * the Intent at that point will <em>not</em> be seen here.
551      *
552      * @return Return an IBinder through which clients can call on to the
553      *         service.
554      */
555     @Nullable
onBind(Intent intent)556     public abstract IBinder onBind(Intent intent);
557 
558     /**
559      * Called when all clients have disconnected from a particular interface
560      * published by the service.  The default implementation does nothing and
561      * returns false.
562      *
563      * @param intent The Intent that was used to bind to this service,
564      * as given to {@link android.content.Context#bindService
565      * Context.bindService}.  Note that any extras that were included with
566      * the Intent at that point will <em>not</em> be seen here.
567      *
568      * @return Return true if you would like to have the service's
569      * {@link #onRebind} method later called when new clients bind to it.
570      */
onUnbind(Intent intent)571     public boolean onUnbind(Intent intent) {
572         return false;
573     }
574 
575     /**
576      * Called when new clients have connected to the service, after it had
577      * previously been notified that all had disconnected in its
578      * {@link #onUnbind}.  This will only be called if the implementation
579      * of {@link #onUnbind} was overridden to return true.
580      *
581      * @param intent The Intent that was used to bind to this service,
582      * as given to {@link android.content.Context#bindService
583      * Context.bindService}.  Note that any extras that were included with
584      * the Intent at that point will <em>not</em> be seen here.
585      */
onRebind(Intent intent)586     public void onRebind(Intent intent) {
587     }
588 
589     /**
590      * This is called if the service is currently running and the user has
591      * removed a task that comes from the service's application.  If you have
592      * set {@link android.content.pm.ServiceInfo#FLAG_STOP_WITH_TASK ServiceInfo.FLAG_STOP_WITH_TASK}
593      * then you will not receive this callback; instead, the service will simply
594      * be stopped.
595      *
596      * @param rootIntent The original root Intent that was used to launch
597      * the task that is being removed.
598      */
onTaskRemoved(Intent rootIntent)599     public void onTaskRemoved(Intent rootIntent) {
600     }
601 
602     /**
603      * Stop the service, if it was previously started.  This is the same as
604      * calling {@link android.content.Context#stopService} for this particular service.
605      *
606      * @see #stopSelfResult(int)
607      */
stopSelf()608     public final void stopSelf() {
609         stopSelf(-1);
610     }
611 
612     /**
613      * Old version of {@link #stopSelfResult} that doesn't return a result.
614      *
615      * @see #stopSelfResult
616      */
stopSelf(int startId)617     public final void stopSelf(int startId) {
618         if (mActivityManager == null) {
619             return;
620         }
621         try {
622             mActivityManager.stopServiceToken(
623                     new ComponentName(this, mClassName), mToken, startId);
624         } catch (RemoteException ex) {
625         }
626     }
627 
628     /**
629      * Stop the service if the most recent time it was started was
630      * <var>startId</var>.  This is the same as calling {@link
631      * android.content.Context#stopService} for this particular service but allows you to
632      * safely avoid stopping if there is a start request from a client that you
633      * haven't yet seen in {@link #onStart}.
634      *
635      * <p><em>Be careful about ordering of your calls to this function.</em>.
636      * If you call this function with the most-recently received ID before
637      * you have called it for previously received IDs, the service will be
638      * immediately stopped anyway.  If you may end up processing IDs out
639      * of order (such as by dispatching them on separate threads), then you
640      * are responsible for stopping them in the same order you received them.</p>
641      *
642      * @param startId The most recent start identifier received in {@link
643      *                #onStart}.
644      * @return Returns true if the startId matches the last start request
645      * and the service will be stopped, else false.
646      *
647      * @see #stopSelf()
648      */
stopSelfResult(int startId)649     public final boolean stopSelfResult(int startId) {
650         if (mActivityManager == null) {
651             return false;
652         }
653         try {
654             return mActivityManager.stopServiceToken(
655                     new ComponentName(this, mClassName), mToken, startId);
656         } catch (RemoteException ex) {
657         }
658         return false;
659     }
660 
661     /**
662      * @deprecated This is a now a no-op, use
663      * {@link #startForeground(int, Notification)} instead.  This method
664      * has been turned into a no-op rather than simply being deprecated
665      * because analysis of numerous poorly behaving devices has shown that
666      * increasingly often the trouble is being caused in part by applications
667      * that are abusing it.  Thus, given a choice between introducing
668      * problems in existing applications using this API (by allowing them to
669      * be killed when they would like to avoid it), vs allowing the performance
670      * of the entire system to be decreased, this method was deemed less
671      * important.
672      *
673      * @hide
674      */
675     @Deprecated
676     @UnsupportedAppUsage
setForeground(boolean isForeground)677     public final void setForeground(boolean isForeground) {
678         Log.w(TAG, "setForeground: ignoring old API call on " + getClass().getName());
679     }
680 
681     /**
682      * If your service is started (running through {@link Context#startService(Intent)}), then
683      * also make this service run in the foreground, supplying the ongoing
684      * notification to be shown to the user while in this state.
685      * By default started services are background, meaning that their process won't be given
686      * foreground CPU scheduling (unless something else in that process is foreground) and,
687      * if the system needs to kill them to reclaim more memory (such as to display a large page in a
688      * web browser), they can be killed without too much harm.  You use
689      * {@link #startForeground} if killing your service would be disruptive to the user, such as
690      * if your service is performing background music playback, so the user
691      * would notice if their music stopped playing.
692      *
693      * <p>Note that calling this method does <em>not</em> put the service in the started state
694      * itself, even though the name sounds like it.  You must always call
695      * {@link #startService(Intent)} first to tell the system it should keep the service running,
696      * and then use this method to tell it to keep it running harder.</p>
697      *
698      * <p>Apps targeting API {@link android.os.Build.VERSION_CODES#P} or later must request
699      * the permission {@link android.Manifest.permission#FOREGROUND_SERVICE} in order to use
700      * this API.</p>
701      *
702      * <p>Apps built with SDK version {@link android.os.Build.VERSION_CODES#Q} or later can specify
703      * the foreground service types using attribute {@link android.R.attr#foregroundServiceType} in
704      * service element of manifest file. The value of attribute
705      * {@link android.R.attr#foregroundServiceType} can be multiple flags ORed together.</p>
706      *
707      * <div class="caution">
708      * <p><strong>Note:</strong>
709      * Beginning with SDK Version {@link android.os.Build.VERSION_CODES#S},
710      * apps targeting SDK Version {@link android.os.Build.VERSION_CODES#S}
711      * or higher are not allowed to start foreground services from the background.
712      * See
713      * <a href="{@docRoot}/about/versions/12/behavior-changes-12">
714      * Behavior changes: Apps targeting Android 12
715      * </a>
716      * for more details.
717      * </div>
718      *
719      * @throws ForegroundServiceStartNotAllowedException
720      * If the app targeting API is
721      * {@link android.os.Build.VERSION_CODES#S} or later, and the service is restricted from
722      * becoming foreground service due to background restriction.
723      *
724      * @param id The identifier for this notification as per
725      * {@link NotificationManager#notify(int, Notification)
726      * NotificationManager.notify(int, Notification)}; must not be 0.
727      * @param notification The Notification to be displayed.
728      *
729      * @see #stopForeground(boolean)
730      */
startForeground(int id, Notification notification)731     public final void startForeground(int id, Notification notification) {
732         try {
733             mActivityManager.setServiceForeground(
734                     new ComponentName(this, mClassName), mToken, id,
735                     notification, 0, FOREGROUND_SERVICE_TYPE_MANIFEST);
736         } catch (RemoteException ex) {
737         }
738     }
739 
740   /**
741    * An overloaded version of {@link #startForeground(int, Notification)} with additional
742    * foregroundServiceType parameter.
743    *
744    * <p>Apps built with SDK version {@link android.os.Build.VERSION_CODES#Q} or later can specify
745    * the foreground service types using attribute {@link android.R.attr#foregroundServiceType} in
746    * service element of manifest file. The value of attribute
747    * {@link android.R.attr#foregroundServiceType} can be multiple flags ORed together.</p>
748    *
749    * <p>The foregroundServiceType parameter must be a subset flags of what is specified in manifest
750    * attribute {@link android.R.attr#foregroundServiceType}, if not, an IllegalArgumentException is
751    * thrown. Specify foregroundServiceType parameter as
752    * {@link android.content.pm.ServiceInfo#FOREGROUND_SERVICE_TYPE_MANIFEST} to use all flags that
753    * is specified in manifest attribute foregroundServiceType.</p>
754    *
755    * <div class="caution">
756    * <p><strong>Note:</strong>
757    * Beginning with SDK Version {@link android.os.Build.VERSION_CODES#S},
758    * apps targeting SDK Version {@link android.os.Build.VERSION_CODES#S}
759    * or higher are not allowed to start foreground services from the background.
760    * See
761    * <a href="{@docRoot}/about/versions/12/behavior-changes-12">
762    * Behavior changes: Apps targeting Android 12
763    * </a>
764    * for more details.
765    * </div>
766    *
767    * @param id The identifier for this notification as per
768    * {@link NotificationManager#notify(int, Notification)
769    * NotificationManager.notify(int, Notification)}; must not be 0.
770    * @param notification The Notification to be displayed.
771    * @param foregroundServiceType must be a subset flags of manifest attribute
772    * {@link android.R.attr#foregroundServiceType} flags.
773    *
774    * @throws IllegalArgumentException if param foregroundServiceType is not subset of manifest
775    *     attribute {@link android.R.attr#foregroundServiceType}.
776    * @throws ForegroundServiceStartNotAllowedException
777    * If the app targeting API is
778    * {@link android.os.Build.VERSION_CODES#S} or later, and the service is restricted from
779    * becoming foreground service due to background restriction.
780    *
781    * @see android.content.pm.ServiceInfo#FOREGROUND_SERVICE_TYPE_MANIFEST
782    */
startForeground(int id, @NonNull Notification notification, @ForegroundServiceType int foregroundServiceType)783     public final void startForeground(int id, @NonNull Notification notification,
784             @ForegroundServiceType int foregroundServiceType) {
785         try {
786             mActivityManager.setServiceForeground(
787                     new ComponentName(this, mClassName), mToken, id,
788                     notification, 0, foregroundServiceType);
789         } catch (RemoteException ex) {
790         }
791     }
792 
793     /**
794      * Synonym for {@link #stopForeground(int)}.
795      * @param removeNotification If true, the {@link #STOP_FOREGROUND_REMOVE} flag
796      * will be supplied.
797      * @see #stopForeground(int)
798      * @see #startForeground(int, Notification)
799      */
stopForeground(boolean removeNotification)800     public final void stopForeground(boolean removeNotification) {
801         stopForeground(removeNotification ? STOP_FOREGROUND_REMOVE : 0);
802     }
803 
804     /**
805      * Remove this service from foreground state, allowing it to be killed if
806      * more memory is needed.  This does not stop the service from running (for that
807      * you use {@link #stopSelf()} or related methods), just takes it out of the
808      * foreground state.
809      *
810      * @param flags additional behavior options.
811      * @see #startForeground(int, Notification)
812      */
stopForeground(@topForegroundFlags int flags)813     public final void stopForeground(@StopForegroundFlags int flags) {
814         try {
815             mActivityManager.setServiceForeground(
816                     new ComponentName(this, mClassName), mToken, 0, null,
817                     flags, 0);
818         } catch (RemoteException ex) {
819         }
820     }
821 
822     /**
823      * If the service has become a foreground service by calling
824      * {@link #startForeground(int, Notification)}
825      * or {@link #startForeground(int, Notification, int)}, {@link #getForegroundServiceType()}
826      * returns the current foreground service type.
827      *
828      * <p>If there is no foregroundServiceType specified
829      * in manifest, {@link ServiceInfo#FOREGROUND_SERVICE_TYPE_NONE} is returned. </p>
830      *
831      * <p>If the service is not a foreground service,
832      * {@link ServiceInfo#FOREGROUND_SERVICE_TYPE_NONE} is returned.</p>
833      *
834      * @return current foreground service type flags.
835      */
getForegroundServiceType()836     public final @ForegroundServiceType int getForegroundServiceType() {
837         int ret = ServiceInfo.FOREGROUND_SERVICE_TYPE_NONE;
838         try {
839             ret = mActivityManager.getForegroundServiceType(
840                     new ComponentName(this, mClassName), mToken);
841         } catch (RemoteException ex) {
842         }
843         return ret;
844     }
845 
846     /**
847      * Print the Service's state into the given stream.  This gets invoked if
848      * you run "adb shell dumpsys activity service &lt;yourservicename&gt;"
849      * (note that for this command to work, the service must be running, and
850      * you must specify a fully-qualified service name).
851      * This is distinct from "dumpsys &lt;servicename&gt;", which only works for
852      * named system services and which invokes the {@link IBinder#dump} method
853      * on the {@link IBinder} interface registered with ServiceManager.
854      *
855      * @param fd The raw file descriptor that the dump is being sent to.
856      * @param writer The PrintWriter to which you should dump your state.  This will be
857      * closed for you after you return.
858      * @param args additional arguments to the dump request.
859      */
dump(FileDescriptor fd, PrintWriter writer, String[] args)860     protected void dump(FileDescriptor fd, PrintWriter writer, String[] args) {
861         writer.println("nothing to dump");
862     }
863 
864     @Override
attachBaseContext(Context newBase)865     protected void attachBaseContext(Context newBase) {
866         super.attachBaseContext(newBase);
867         if (newBase != null) {
868             newBase.setContentCaptureOptions(getContentCaptureOptions());
869         }
870     }
871 
872     // ------------------ Internal API ------------------
873 
874     /**
875      * @hide
876      */
877     @UnsupportedAppUsage
attach( Context context, ActivityThread thread, String className, IBinder token, Application application, Object activityManager)878     public final void attach(
879             Context context,
880             ActivityThread thread, String className, IBinder token,
881             Application application, Object activityManager) {
882         attachBaseContext(context);
883         mThread = thread;           // NOTE:  unused - remove?
884         mClassName = className;
885         mToken = token;
886         mApplication = application;
887         mActivityManager = (IActivityManager)activityManager;
888         mStartCompatibility = getApplicationInfo().targetSdkVersion
889                 < Build.VERSION_CODES.ECLAIR;
890 
891         setContentCaptureOptions(application.getContentCaptureOptions());
892     }
893 
894     /**
895      * Creates the base {@link Context} of this {@link Service}.
896      * Users may override this API to create customized base context.
897      *
898      * @see android.window.WindowProviderService WindowProviderService class for example
899      * @see ContextWrapper#attachBaseContext(Context)
900      *
901      * @hide
902      */
903     public Context createServiceBaseContext(ActivityThread mainThread, LoadedApk packageInfo) {
904         return ContextImpl.createAppContext(mainThread, packageInfo);
905     }
906 
907     /**
908      * @hide
909      * Clean up any references to avoid leaks.
910      */
911     public final void detachAndCleanUp() {
912         mToken = null;
913     }
914 
915     final String getClassName() {
916         return mClassName;
917     }
918 
919     /** @hide */
920     @Override
921     public final ContentCaptureManager.ContentCaptureClient getContentCaptureClient() {
922         return this;
923     }
924 
925     /** @hide */
926     @Override
927     public final ComponentName contentCaptureClientGetComponentName() {
928         return new ComponentName(this, mClassName);
929     }
930 
931     // set by the thread after the constructor and before onCreate(Bundle icicle) is called.
932     @UnsupportedAppUsage
933     private ActivityThread mThread = null;
934     @UnsupportedAppUsage
935     private String mClassName = null;
936     @UnsupportedAppUsage
937     private IBinder mToken = null;
938     @UnsupportedAppUsage
939     private Application mApplication = null;
940     @UnsupportedAppUsage
941     private IActivityManager mActivityManager = null;
942     @UnsupportedAppUsage
943     private boolean mStartCompatibility = false;
944 }
945