The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 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.content; |
| 18 | |
| 19 | import android.app.ActivityManagerNative; |
| 20 | import android.app.IActivityManager; |
| 21 | import android.os.Bundle; |
| 22 | import android.os.IBinder; |
| 23 | import android.os.RemoteException; |
| 24 | import android.util.Log; |
| 25 | |
| 26 | /** |
| 27 | * Base class for code that will receive intents sent by sendBroadcast(). |
| 28 | * You can either dynamically register an instance of this class with |
| 29 | * {@link Context#registerReceiver Context.registerReceiver()} |
| 30 | * or statically publish an implementation through the |
| 31 | * {@link android.R.styleable#AndroidManifestReceiver <receiver>} |
| 32 | * tag in your <code>AndroidManifest.xml</code>. <em><strong>Note:</strong></em> |
| 33 | * If registering a receiver in your |
| 34 | * {@link android.app.Activity#onResume() Activity.onResume()} |
| 35 | * implementation, you should unregister it in |
| 36 | * {@link android.app.Activity#onPause() Activity.onPause()}. |
| 37 | * (You won't receive intents when paused, |
| 38 | * and this will cut down on unnecessary system overhead). Do not unregister in |
| 39 | * {@link android.app.Activity#onSaveInstanceState(android.os.Bundle) Activity.onSaveInstanceState()}, |
| 40 | * because this won't be called if the user moves back in the history |
| 41 | * stack. |
| 42 | * |
| 43 | * <p>There are two major classes of broadcasts that can be received:</p> |
| 44 | * <ul> |
| 45 | * <li> <b>Normal broadcasts</b> (sent with {@link Context#sendBroadcast(Intent) |
| 46 | * Context.sendBroadcast}) are completely asynchronous. All receivers of the |
Chris Tate | a34df8a2 | 2009-04-02 23:15:58 -0700 | [diff] [blame] | 47 | * broadcast are run in an undefined order, often at the same time. This is |
| 48 | * more efficient, but means that receivers cannot use the result or abort |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 49 | * APIs included here. |
| 50 | * <li> <b>Ordered broadcasts</b> (sent with {@link Context#sendOrderedBroadcast(Intent, String) |
| 51 | * Context.sendOrderedBroadcast}) are delivered to one receiver at a time. |
| 52 | * As each receiver executes in turn, it can propagate a result to the next |
| 53 | * receiver, or it can completely abort the broadcast so that it won't be passed |
Chris Tate | a34df8a2 | 2009-04-02 23:15:58 -0700 | [diff] [blame] | 54 | * to other receivers. The order receivers run in can be controlled with the |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 55 | * {@link android.R.styleable#AndroidManifestIntentFilter_priority |
| 56 | * android:priority} attribute of the matching intent-filter; receivers with |
| 57 | * the same priority will be run in an arbitrary order. |
| 58 | * </ul> |
| 59 | * |
| 60 | * <p>Even in the case of normal broadcasts, the system may in some |
| 61 | * situations revert to delivering the broadcast one receiver at a time. In |
| 62 | * particular, for receivers that may require the creation of a process, only |
| 63 | * one will be run at a time to avoid overloading the system with new processes. |
Chris Tate | a34df8a2 | 2009-04-02 23:15:58 -0700 | [diff] [blame] | 64 | * In this situation, however, the non-ordered semantics hold: these receivers still |
| 65 | * cannot return results or abort their broadcast.</p> |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 66 | * |
| 67 | * <p>Note that, although the Intent class is used for sending and receiving |
| 68 | * these broadcasts, the Intent broadcast mechanism here is completely separate |
| 69 | * from Intents that are used to start Activities with |
| 70 | * {@link Context#startActivity Context.startActivity()}. |
The Android Open Source Project | 1059253 | 2009-03-18 17:39:46 -0700 | [diff] [blame] | 71 | * There is no way for a BroadcastReceiver |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 72 | * to see or capture Intents used with startActivity(); likewise, when |
| 73 | * you broadcast an Intent, you will never find or start an Activity. |
| 74 | * These two operations are semantically very different: starting an |
| 75 | * Activity with an Intent is a foreground operation that modifies what the |
| 76 | * user is currently interacting with; broadcasting an Intent is a background |
| 77 | * operation that the user is not normally aware of. |
| 78 | * |
| 79 | * <p>The BroadcastReceiver class (when launched as a component through |
| 80 | * a manifest's {@link android.R.styleable#AndroidManifestReceiver <receiver>} |
| 81 | * tag) is an important part of an |
| 82 | * <a href="{@docRoot}guide/topics/fundamentals.html#lcycles">application's overall lifecycle</a>.</p> |
| 83 | * |
| 84 | * <p>Topics covered here: |
| 85 | * <ol> |
| 86 | * <li><a href="#ReceiverLifecycle">Receiver Lifecycle</a> |
| 87 | * <li><a href="#Permissions">Permissions</a> |
| 88 | * <li><a href="#ProcessLifecycle">Process Lifecycle</a> |
| 89 | * </ol> |
| 90 | * |
| 91 | * <a name="ReceiverLifecycle"></a> |
| 92 | * <h3>Receiver Lifecycle</h3> |
| 93 | * |
| 94 | * <p>A BroadcastReceiver object is only valid for the duration of the call |
| 95 | * to {@link #onReceive}. Once your code returns from this function, |
| 96 | * the system considers the object to be finished and no longer active. |
| 97 | * |
| 98 | * <p>This has important repercussions to what you can do in an |
| 99 | * {@link #onReceive} implementation: anything that requires asynchronous |
| 100 | * operation is not available, because you will need to return from the |
| 101 | * function to handle the asynchronous operation, but at that point the |
| 102 | * BroadcastReceiver is no longer active and thus the system is free to kill |
| 103 | * its process before the asynchronous operation completes. |
| 104 | * |
| 105 | * <p>In particular, you may <i>not</i> show a dialog or bind to a service from |
The Android Open Source Project | 1059253 | 2009-03-18 17:39:46 -0700 | [diff] [blame] | 106 | * within a BroadcastReceiver. For the former, you should instead use the |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 107 | * {@link android.app.NotificationManager} API. For the latter, you can |
| 108 | * use {@link android.content.Context#startService Context.startService()} to |
| 109 | * send a command to the service. |
| 110 | * |
| 111 | * <a name="Permissions"></a> |
| 112 | * <h3>Permissions</h3> |
| 113 | * |
| 114 | * <p>Access permissions can be enforced by either the sender or receiver |
| 115 | * of an Intent. |
| 116 | * |
| 117 | * <p>To enforce a permission when sending, you supply a non-null |
| 118 | * <var>permission</var> argument to |
| 119 | * {@link Context#sendBroadcast(Intent, String)} or |
| 120 | * {@link Context#sendOrderedBroadcast(Intent, String, BroadcastReceiver, android.os.Handler, int, String, Bundle)}. |
| 121 | * Only receivers who have been granted this permission |
| 122 | * (by requesting it with the |
| 123 | * {@link android.R.styleable#AndroidManifestUsesPermission <uses-permission>} |
| 124 | * tag in their <code>AndroidManifest.xml</code>) will be able to receive |
| 125 | * the broadcast. |
| 126 | * |
| 127 | * <p>To enforce a permission when receiving, you supply a non-null |
| 128 | * <var>permission</var> when registering your receiver -- either when calling |
| 129 | * {@link Context#registerReceiver(BroadcastReceiver, IntentFilter, String, android.os.Handler)} |
| 130 | * or in the static |
| 131 | * {@link android.R.styleable#AndroidManifestReceiver <receiver>} |
| 132 | * tag in your <code>AndroidManifest.xml</code>. Only broadcasters who have |
| 133 | * been granted this permission (by requesting it with the |
| 134 | * {@link android.R.styleable#AndroidManifestUsesPermission <uses-permission>} |
| 135 | * tag in their <code>AndroidManifest.xml</code>) will be able to send an |
| 136 | * Intent to the receiver. |
| 137 | * |
| 138 | * <p>See the <a href="{@docRoot}guide/topics/security/security.html">Security and Permissions</a> |
| 139 | * document for more information on permissions and security in general. |
| 140 | * |
| 141 | * <a name="ProcessLifecycle"></a> |
| 142 | * <h3>Process Lifecycle</h3> |
| 143 | * |
The Android Open Source Project | 1059253 | 2009-03-18 17:39:46 -0700 | [diff] [blame] | 144 | * <p>A process that is currently executing a BroadcastReceiver (that is, |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 145 | * currently running the code in its {@link #onReceive} method) is |
| 146 | * considered to be a foreground process and will be kept running by the |
| 147 | * system except under cases of extreme memory pressure. |
| 148 | * |
| 149 | * <p>Once you return from onReceive(), the BroadcastReceiver is no longer |
| 150 | * active, and its hosting process is only as important as any other application |
| 151 | * components that are running in it. This is especially important because if |
| 152 | * that process was only hosting the BroadcastReceiver (a common case for |
| 153 | * applications that the user has never or not recently interacted with), then |
| 154 | * upon returning from onReceive() the system will consider its process |
| 155 | * to be empty and aggressively kill it so that resources are available for other |
| 156 | * more important processes. |
| 157 | * |
| 158 | * <p>This means that for longer-running operations you will often use |
Chris Tate | a34df8a2 | 2009-04-02 23:15:58 -0700 | [diff] [blame] | 159 | * a {@link android.app.Service} in conjunction with a BroadcastReceiver to keep |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 160 | * the containing process active for the entire time of your operation. |
| 161 | */ |
| 162 | public abstract class BroadcastReceiver { |
| 163 | public BroadcastReceiver() { |
| 164 | } |
| 165 | |
| 166 | /** |
| 167 | * This method is called when the BroadcastReceiver is receiving an Intent |
| 168 | * broadcast. During this time you can use the other methods on |
| 169 | * BroadcastReceiver to view/modify the current result values. The function |
Chris Tate | a34df8a2 | 2009-04-02 23:15:58 -0700 | [diff] [blame] | 170 | * is normally called within the main thread of its process, so you should |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 171 | * never perform long-running operations in it (there is a timeout of |
| 172 | * 10 seconds that the system allows before considering the receiver to |
| 173 | * be blocked and a candidate to be killed). You cannot launch a popup dialog |
| 174 | * in your implementation of onReceive(). |
| 175 | * |
| 176 | * <p><b>If this BroadcastReceiver was launched through a <receiver> tag, |
| 177 | * then the object is no longer alive after returning from this |
| 178 | * function.</b> This means you should not perform any operations that |
| 179 | * return a result to you asynchronously -- in particular, for interacting |
| 180 | * with services, you should use |
| 181 | * {@link Context#startService(Intent)} instead of |
| 182 | * {@link Context#bindService(Intent, ServiceConnection, int)}. If you wish |
| 183 | * to interact with a service that is already running, you can use |
| 184 | * {@link #peekService}. |
| 185 | * |
Chris Tate | a34df8a2 | 2009-04-02 23:15:58 -0700 | [diff] [blame] | 186 | * <p>The Intent filters used in {@link android.content.Context#registerReceiver} |
| 187 | * and in application manifests are <em>not</em> guaranteed to be exclusive. They |
| 188 | * are hints to the operating system about how to find suitable recipients. It is |
| 189 | * possible for senders to force delivery to specific recipients, bypassing filter |
| 190 | * resolution. For this reason, {@link #onReceive(Context, Intent) onReceive()} |
| 191 | * implementations should respond only to known actions, ignoring any unexpected |
| 192 | * Intents that they may receive. |
| 193 | * |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 194 | * @param context The Context in which the receiver is running. |
| 195 | * @param intent The Intent being received. |
| 196 | */ |
| 197 | public abstract void onReceive(Context context, Intent intent); |
| 198 | |
| 199 | /** |
| 200 | * Provide a binder to an already-running service. This method is synchronous |
| 201 | * and will not start the target service if it is not present, so it is safe |
| 202 | * to call from {@link #onReceive}. |
| 203 | * |
| 204 | * @param myContext The Context that had been passed to {@link #onReceive(Context, Intent)} |
| 205 | * @param service The Intent indicating the service you wish to use. See {@link |
| 206 | * Context#startService(Intent)} for more information. |
| 207 | */ |
| 208 | public IBinder peekService(Context myContext, Intent service) { |
| 209 | IActivityManager am = ActivityManagerNative.getDefault(); |
| 210 | IBinder binder = null; |
| 211 | try { |
| 212 | binder = am.peekService(service, service.resolveTypeIfNeeded( |
| 213 | myContext.getContentResolver())); |
| 214 | } catch (RemoteException e) { |
| 215 | } |
| 216 | return binder; |
| 217 | } |
| 218 | |
| 219 | /** |
| 220 | * Change the current result code of this broadcast; only works with |
| 221 | * broadcasts sent through |
| 222 | * {@link Context#sendOrderedBroadcast(Intent, String) |
| 223 | * Context.sendOrderedBroadcast}. Often uses the |
| 224 | * Activity {@link android.app.Activity#RESULT_CANCELED} and |
| 225 | * {@link android.app.Activity#RESULT_OK} constants, though the |
| 226 | * actual meaning of this value is ultimately up to the broadcaster. |
| 227 | * |
| 228 | * <p><strong>This method does not work with non-ordered broadcasts such |
| 229 | * as those sent with {@link Context#sendBroadcast(Intent) |
| 230 | * Context.sendBroadcast}</strong></p> |
| 231 | * |
| 232 | * @param code The new result code. |
| 233 | * |
| 234 | * @see #setResult(int, String, Bundle) |
| 235 | */ |
| 236 | public final void setResultCode(int code) { |
| 237 | checkSynchronousHint(); |
| 238 | mResultCode = code; |
| 239 | } |
| 240 | |
| 241 | /** |
| 242 | * Retrieve the current result code, as set by the previous receiver. |
| 243 | * |
| 244 | * @return int The current result code. |
| 245 | */ |
| 246 | public final int getResultCode() { |
| 247 | return mResultCode; |
| 248 | } |
| 249 | |
| 250 | /** |
| 251 | * Change the current result data of this broadcast; only works with |
| 252 | * broadcasts sent through |
| 253 | * {@link Context#sendOrderedBroadcast(Intent, String) |
| 254 | * Context.sendOrderedBroadcast}. This is an arbitrary |
| 255 | * string whose interpretation is up to the broadcaster. |
| 256 | * |
| 257 | * <p><strong>This method does not work with non-ordered broadcasts such |
| 258 | * as those sent with {@link Context#sendBroadcast(Intent) |
| 259 | * Context.sendBroadcast}</strong></p> |
| 260 | * |
| 261 | * @param data The new result data; may be null. |
| 262 | * |
| 263 | * @see #setResult(int, String, Bundle) |
| 264 | */ |
| 265 | public final void setResultData(String data) { |
| 266 | checkSynchronousHint(); |
| 267 | mResultData = data; |
| 268 | } |
| 269 | |
| 270 | /** |
| 271 | * Retrieve the current result data, as set by the previous receiver. |
| 272 | * Often this is null. |
| 273 | * |
| 274 | * @return String The current result data; may be null. |
| 275 | */ |
| 276 | public final String getResultData() { |
| 277 | return mResultData; |
| 278 | } |
| 279 | |
| 280 | /** |
| 281 | * Change the current result extras of this broadcast; only works with |
| 282 | * broadcasts sent through |
| 283 | * {@link Context#sendOrderedBroadcast(Intent, String) |
| 284 | * Context.sendOrderedBroadcast}. This is a Bundle |
| 285 | * holding arbitrary data, whose interpretation is up to the |
| 286 | * broadcaster. Can be set to null. Calling this method completely |
| 287 | * replaces the current map (if any). |
| 288 | * |
| 289 | * <p><strong>This method does not work with non-ordered broadcasts such |
| 290 | * as those sent with {@link Context#sendBroadcast(Intent) |
| 291 | * Context.sendBroadcast}</strong></p> |
| 292 | * |
| 293 | * @param extras The new extra data map; may be null. |
| 294 | * |
| 295 | * @see #setResult(int, String, Bundle) |
| 296 | */ |
| 297 | public final void setResultExtras(Bundle extras) { |
| 298 | checkSynchronousHint(); |
| 299 | mResultExtras = extras; |
| 300 | } |
| 301 | |
| 302 | /** |
| 303 | * Retrieve the current result extra data, as set by the previous receiver. |
| 304 | * Any changes you make to the returned Map will be propagated to the next |
| 305 | * receiver. |
| 306 | * |
| 307 | * @param makeMap If true then a new empty Map will be made for you if the |
| 308 | * current Map is null; if false you should be prepared to |
| 309 | * receive a null Map. |
| 310 | * |
| 311 | * @return Map The current extras map. |
| 312 | */ |
| 313 | public final Bundle getResultExtras(boolean makeMap) { |
| 314 | Bundle e = mResultExtras; |
| 315 | if (!makeMap) return e; |
| 316 | if (e == null) mResultExtras = e = new Bundle(); |
| 317 | return e; |
| 318 | } |
| 319 | |
| 320 | /** |
| 321 | * Change all of the result data returned from this broadcasts; only works |
| 322 | * with broadcasts sent through |
| 323 | * {@link Context#sendOrderedBroadcast(Intent, String) |
| 324 | * Context.sendOrderedBroadcast}. All current result data is replaced |
| 325 | * by the value given to this method. |
| 326 | * |
| 327 | * <p><strong>This method does not work with non-ordered broadcasts such |
| 328 | * as those sent with {@link Context#sendBroadcast(Intent) |
| 329 | * Context.sendBroadcast}</strong></p> |
| 330 | * |
| 331 | * @param code The new result code. Often uses the |
| 332 | * Activity {@link android.app.Activity#RESULT_CANCELED} and |
| 333 | * {@link android.app.Activity#RESULT_OK} constants, though the |
| 334 | * actual meaning of this value is ultimately up to the broadcaster. |
| 335 | * @param data The new result data. This is an arbitrary |
| 336 | * string whose interpretation is up to the broadcaster; may be null. |
| 337 | * @param extras The new extra data map. This is a Bundle |
| 338 | * holding arbitrary data, whose interpretation is up to the |
| 339 | * broadcaster. Can be set to null. This completely |
| 340 | * replaces the current map (if any). |
| 341 | */ |
| 342 | public final void setResult(int code, String data, Bundle extras) { |
| 343 | checkSynchronousHint(); |
| 344 | mResultCode = code; |
| 345 | mResultData = data; |
| 346 | mResultExtras = extras; |
| 347 | } |
| 348 | |
| 349 | /** |
| 350 | * Returns the flag indicating whether or not this receiver should |
| 351 | * abort the current broadcast. |
| 352 | * |
| 353 | * @return True if the broadcast should be aborted. |
| 354 | */ |
| 355 | public final boolean getAbortBroadcast() { |
| 356 | return mAbortBroadcast; |
| 357 | } |
| 358 | |
| 359 | /** |
| 360 | * Sets the flag indicating that this receiver should abort the |
| 361 | * current broadcast; only works with broadcasts sent through |
| 362 | * {@link Context#sendOrderedBroadcast(Intent, String) |
| 363 | * Context.sendOrderedBroadcast}. This will prevent |
| 364 | * any other broadcast receivers from receiving the broadcast. It will still |
| 365 | * call {@link #onReceive} of the BroadcastReceiver that the caller of |
| 366 | * {@link Context#sendOrderedBroadcast(Intent, String) |
| 367 | * Context.sendOrderedBroadcast} passed in. |
| 368 | * |
| 369 | * <p><strong>This method does not work with non-ordered broadcasts such |
| 370 | * as those sent with {@link Context#sendBroadcast(Intent) |
| 371 | * Context.sendBroadcast}</strong></p> |
| 372 | */ |
| 373 | public final void abortBroadcast() { |
| 374 | checkSynchronousHint(); |
| 375 | mAbortBroadcast = true; |
| 376 | } |
| 377 | |
| 378 | /** |
| 379 | * Clears the flag indicating that this receiver should abort the current |
| 380 | * broadcast. |
| 381 | */ |
| 382 | public final void clearAbortBroadcast() { |
| 383 | mAbortBroadcast = false; |
| 384 | } |
| 385 | |
| 386 | /** |
| 387 | * For internal use, sets the hint about whether this BroadcastReceiver is |
| 388 | * running in ordered mode. |
| 389 | */ |
| 390 | public final void setOrderedHint(boolean isOrdered) { |
| 391 | mOrderedHint = isOrdered; |
| 392 | } |
| 393 | |
| 394 | /** |
| 395 | * Control inclusion of debugging help for mismatched |
| 396 | * calls to {@ Context#registerReceiver(BroadcastReceiver, IntentFilter) |
| 397 | * Context.registerReceiver()}. |
| 398 | * If called with true, before given to registerReceiver(), then the |
| 399 | * callstack of the following {@link Context#unregisterReceiver(BroadcastReceiver) |
| 400 | * Context.unregisterReceiver()} call is retained, to be printed if a later |
| 401 | * incorrect unregister call is made. Note that doing this requires retaining |
| 402 | * information about the BroadcastReceiver for the lifetime of the app, |
| 403 | * resulting in a leak -- this should only be used for debugging. |
| 404 | */ |
| 405 | public final void setDebugUnregister(boolean debug) { |
| 406 | mDebugUnregister = debug; |
| 407 | } |
| 408 | |
| 409 | /** |
| 410 | * Return the last value given to {@link #setDebugUnregister}. |
| 411 | */ |
| 412 | public final boolean getDebugUnregister() { |
| 413 | return mDebugUnregister; |
| 414 | } |
| 415 | |
| 416 | void checkSynchronousHint() { |
| 417 | if (mOrderedHint) { |
| 418 | return; |
| 419 | } |
| 420 | RuntimeException e = new RuntimeException( |
| 421 | "BroadcastReceiver trying to return result during a non-ordered broadcast"); |
| 422 | e.fillInStackTrace(); |
| 423 | Log.e("BroadcastReceiver", e.getMessage(), e); |
| 424 | } |
| 425 | |
| 426 | private int mResultCode; |
| 427 | private String mResultData; |
| 428 | private Bundle mResultExtras; |
| 429 | private boolean mAbortBroadcast; |
| 430 | private boolean mDebugUnregister; |
| 431 | private boolean mOrderedHint; |
| 432 | } |
| 433 | |