PowerManager.java revision a1f1a3c573acd91024fda0ceb3b921c73b186963
1/* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.os; 18 19import android.content.Context; 20import android.util.Log; 21 22/** 23 * This class gives you control of the power state of the device. 24 * 25 * <p> 26 * <b>Device battery life will be significantly affected by the use of this API.</b> 27 * Do not acquire {@link WakeLock}s unless you really need them, use the minimum levels 28 * possible, and be sure to release them as soon as possible. 29 * </p><p> 30 * You can obtain an instance of this class by calling 31 * {@link android.content.Context#getSystemService(java.lang.String) Context.getSystemService()}. 32 * </p><p> 33 * The primary API you'll use is {@link #newWakeLock(int, String) newWakeLock()}. 34 * This will create a {@link PowerManager.WakeLock} object. You can then use methods 35 * on the wake lock object to control the power state of the device. 36 * </p><p> 37 * In practice it's quite simple: 38 * {@samplecode 39 * PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE); 40 * PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "My Tag"); 41 * wl.acquire(); 42 * ..screen will stay on during this section.. 43 * wl.release(); 44 * } 45 * </p><p> 46 * The following wake lock levels are defined, with varying effects on system power. 47 * <i>These levels are mutually exclusive - you may only specify one of them.</i> 48 * 49 * <table> 50 * <tr><th>Flag Value</th> 51 * <th>CPU</th> <th>Screen</th> <th>Keyboard</th></tr> 52 * 53 * <tr><td>{@link #PARTIAL_WAKE_LOCK}</td> 54 * <td>On*</td> <td>Off</td> <td>Off</td> 55 * </tr> 56 * 57 * <tr><td>{@link #SCREEN_DIM_WAKE_LOCK}</td> 58 * <td>On</td> <td>Dim</td> <td>Off</td> 59 * </tr> 60 * 61 * <tr><td>{@link #SCREEN_BRIGHT_WAKE_LOCK}</td> 62 * <td>On</td> <td>Bright</td> <td>Off</td> 63 * </tr> 64 * 65 * <tr><td>{@link #FULL_WAKE_LOCK}</td> 66 * <td>On</td> <td>Bright</td> <td>Bright</td> 67 * </tr> 68 * </table> 69 * </p><p> 70 * *<i>If you hold a partial wake lock, the CPU will continue to run, regardless of any 71 * display timeouts or the state of the screen and even after the user presses the power button. 72 * In all other wake locks, the CPU will run, but the user can still put the device to sleep 73 * using the power button.</i> 74 * </p><p> 75 * In addition, you can add two more flags, which affect behavior of the screen only. 76 * <i>These flags have no effect when combined with a {@link #PARTIAL_WAKE_LOCK}.</i></p> 77 * 78 * <table> 79 * <tr><th>Flag Value</th> <th>Description</th></tr> 80 * 81 * <tr><td>{@link #ACQUIRE_CAUSES_WAKEUP}</td> 82 * <td>Normal wake locks don't actually turn on the illumination. Instead, they cause 83 * the illumination to remain on once it turns on (e.g. from user activity). This flag 84 * will force the screen and/or keyboard to turn on immediately, when the WakeLock is 85 * acquired. A typical use would be for notifications which are important for the user to 86 * see immediately.</td> 87 * </tr> 88 * 89 * <tr><td>{@link #ON_AFTER_RELEASE}</td> 90 * <td>If this flag is set, the user activity timer will be reset when the WakeLock is 91 * released, causing the illumination to remain on a bit longer. This can be used to 92 * reduce flicker if you are cycling between wake lock conditions.</td> 93 * </tr> 94 * </table> 95 * <p> 96 * Any application using a WakeLock must request the {@code android.permission.WAKE_LOCK} 97 * permission in an {@code <uses-permission>} element of the application's manifest. 98 * </p> 99 */ 100public final class PowerManager { 101 private static final String TAG = "PowerManager"; 102 103 /* NOTE: Wake lock levels were previously defined as a bit field, except that only a few 104 * combinations were actually supported so the bit field was removed. This explains 105 * why the numbering scheme is so odd. If adding a new wake lock level, any unused 106 * value can be used. 107 */ 108 109 /** 110 * Wake lock level: Ensures that the CPU is running; the screen and keyboard 111 * backlight will be allowed to go off. 112 * <p> 113 * If the user presses the power button, then the screen will be turned off 114 * but the CPU will be kept on until all partial wake locks have been released. 115 * </p> 116 */ 117 public static final int PARTIAL_WAKE_LOCK = 0x00000001; 118 119 /** 120 * Wake lock level: Ensures that the screen is on (but may be dimmed); 121 * the keyboard backlight will be allowed to go off. 122 * <p> 123 * If the user presses the power button, then the {@link #SCREEN_DIM_WAKE_LOCK} will be 124 * implicitly released by the system, causing both the screen and the CPU to be turned off. 125 * Contrast with {@link #PARTIAL_WAKE_LOCK}. 126 * </p> 127 * 128 * @deprecated Most applications should use 129 * {@link android.view.WindowManager.LayoutParams#FLAG_KEEP_SCREEN_ON} instead 130 * of this type of wake lock, as it will be correctly managed by the platform 131 * as the user moves between applications and doesn't require a special permission. 132 */ 133 @Deprecated 134 public static final int SCREEN_DIM_WAKE_LOCK = 0x00000006; 135 136 /** 137 * Wake lock level: Ensures that the screen is on at full brightness; 138 * the keyboard backlight will be allowed to go off. 139 * <p> 140 * If the user presses the power button, then the {@link #SCREEN_BRIGHT_WAKE_LOCK} will be 141 * implicitly released by the system, causing both the screen and the CPU to be turned off. 142 * Contrast with {@link #PARTIAL_WAKE_LOCK}. 143 * </p> 144 * 145 * @deprecated Most applications should use 146 * {@link android.view.WindowManager.LayoutParams#FLAG_KEEP_SCREEN_ON} instead 147 * of this type of wake lock, as it will be correctly managed by the platform 148 * as the user moves between applications and doesn't require a special permission. 149 */ 150 @Deprecated 151 public static final int SCREEN_BRIGHT_WAKE_LOCK = 0x0000000a; 152 153 /** 154 * Wake lock level: Ensures that the screen and keyboard backlight are on at 155 * full brightness. 156 * <p> 157 * If the user presses the power button, then the {@link #FULL_WAKE_LOCK} will be 158 * implicitly released by the system, causing both the screen and the CPU to be turned off. 159 * Contrast with {@link #PARTIAL_WAKE_LOCK}. 160 * </p> 161 * 162 * @deprecated Most applications should use 163 * {@link android.view.WindowManager.LayoutParams#FLAG_KEEP_SCREEN_ON} instead 164 * of this type of wake lock, as it will be correctly managed by the platform 165 * as the user moves between applications and doesn't require a special permission. 166 */ 167 @Deprecated 168 public static final int FULL_WAKE_LOCK = 0x0000001a; 169 170 /** 171 * Wake lock level: Turns the screen off when the proximity sensor activates. 172 * <p> 173 * If the proximity sensor detects that an object is nearby, the screen turns off 174 * immediately. Shortly after the object moves away, the screen turns on again. 175 * </p><p> 176 * A proximity wake lock does not prevent the device from falling asleep 177 * unlike {@link #FULL_WAKE_LOCK}, {@link #SCREEN_BRIGHT_WAKE_LOCK} and 178 * {@link #SCREEN_DIM_WAKE_LOCK}. If there is no user activity and no other 179 * wake locks are held, then the device will fall asleep (and lock) as usual. 180 * However, the device will not fall asleep while the screen has been turned off 181 * by the proximity sensor because it effectively counts as ongoing user activity. 182 * </p><p> 183 * Since not all devices have proximity sensors, use {@link #isWakeLockLevelSupported} 184 * to determine whether this wake lock level is supported. 185 * </p><p> 186 * Cannot be used with {@link #ACQUIRE_CAUSES_WAKEUP}. 187 * </p> 188 * 189 * {@hide} 190 */ 191 public static final int PROXIMITY_SCREEN_OFF_WAKE_LOCK = 0x00000020; 192 193 /** 194 * Wake lock level: Put the screen in a low power state and allow the CPU to suspend 195 * if no other wake locks are held. 196 * <p> 197 * This is used by the dream manager to implement doze mode. It currently 198 * has no effect unless the power manager is in the dozing state. 199 * </p> 200 * 201 * {@hide} 202 */ 203 public static final int DOZE_WAKE_LOCK = 0x00000040; 204 205 /** 206 * Mask for the wake lock level component of a combined wake lock level and flags integer. 207 * 208 * @hide 209 */ 210 public static final int WAKE_LOCK_LEVEL_MASK = 0x0000ffff; 211 212 /** 213 * Wake lock flag: Turn the screen on when the wake lock is acquired. 214 * <p> 215 * Normally wake locks don't actually wake the device, they just cause 216 * the screen to remain on once it's already on. Think of the video player 217 * application as the normal behavior. Notifications that pop up and want 218 * the device to be on are the exception; use this flag to be like them. 219 * </p><p> 220 * Cannot be used with {@link #PARTIAL_WAKE_LOCK}. 221 * </p> 222 */ 223 public static final int ACQUIRE_CAUSES_WAKEUP = 0x10000000; 224 225 /** 226 * Wake lock flag: When this wake lock is released, poke the user activity timer 227 * so the screen stays on for a little longer. 228 * <p> 229 * Will not turn the screen on if it is not already on. 230 * See {@link #ACQUIRE_CAUSES_WAKEUP} if you want that. 231 * </p><p> 232 * Cannot be used with {@link #PARTIAL_WAKE_LOCK}. 233 * </p> 234 */ 235 public static final int ON_AFTER_RELEASE = 0x20000000; 236 237 /** 238 * Wake lock flag: This wake lock is not important for logging events. If a later 239 * wake lock is acquired that is important, it will be considered the one to log. 240 * @hide 241 */ 242 public static final int UNIMPORTANT_FOR_LOGGING = 0x40000000; 243 244 /** 245 * Flag for {@link WakeLock#release release(int)} to defer releasing a 246 * {@link #PROXIMITY_SCREEN_OFF_WAKE_LOCK} wake lock until the proximity sensor returns 247 * a negative value. 248 * 249 * {@hide} 250 */ 251 public static final int WAIT_FOR_PROXIMITY_NEGATIVE = 1; 252 253 /** 254 * Brightness value for fully on. 255 * @hide 256 */ 257 public static final int BRIGHTNESS_ON = 255; 258 259 /** 260 * Brightness value for fully off. 261 * @hide 262 */ 263 public static final int BRIGHTNESS_OFF = 0; 264 265 // Note: Be sure to update android.os.BatteryStats and PowerManager.h 266 // if adding or modifying user activity event constants. 267 268 /** 269 * User activity event type: Unspecified event type. 270 * @hide 271 */ 272 public static final int USER_ACTIVITY_EVENT_OTHER = 0; 273 274 /** 275 * User activity event type: Button or key pressed or released. 276 * @hide 277 */ 278 public static final int USER_ACTIVITY_EVENT_BUTTON = 1; 279 280 /** 281 * User activity event type: Touch down, move or up. 282 * @hide 283 */ 284 public static final int USER_ACTIVITY_EVENT_TOUCH = 2; 285 286 /** 287 * User activity flag: Do not restart the user activity timeout or brighten 288 * the display in response to user activity if it is already dimmed. 289 * @hide 290 */ 291 public static final int USER_ACTIVITY_FLAG_NO_CHANGE_LIGHTS = 1 << 0; 292 293 /** 294 * Go to sleep reason code: Going to sleep due by user request. 295 * @hide 296 */ 297 public static final int GO_TO_SLEEP_REASON_USER = 0; 298 299 /** 300 * Go to sleep reason code: Going to sleep due by request of the 301 * device administration policy. 302 * @hide 303 */ 304 public static final int GO_TO_SLEEP_REASON_DEVICE_ADMIN = 1; 305 306 /** 307 * Go to sleep reason code: Going to sleep due to a screen timeout. 308 * @hide 309 */ 310 public static final int GO_TO_SLEEP_REASON_TIMEOUT = 2; 311 312 /** 313 * The value to pass as the 'reason' argument to reboot() to 314 * reboot into recovery mode (for applying system updates, doing 315 * factory resets, etc.). 316 * <p> 317 * Requires the {@link android.Manifest.permission#RECOVERY} 318 * permission (in addition to 319 * {@link android.Manifest.permission#REBOOT}). 320 * </p> 321 */ 322 public static final String REBOOT_RECOVERY = "recovery"; 323 324 final Context mContext; 325 final IPowerManager mService; 326 final Handler mHandler; 327 328 /** 329 * {@hide} 330 */ 331 public PowerManager(Context context, IPowerManager service, Handler handler) { 332 mContext = context; 333 mService = service; 334 mHandler = handler; 335 } 336 337 /** 338 * Gets the minimum supported screen brightness setting. 339 * The screen may be allowed to become dimmer than this value but 340 * this is the minimum value that can be set by the user. 341 * @hide 342 */ 343 public int getMinimumScreenBrightnessSetting() { 344 return mContext.getResources().getInteger( 345 com.android.internal.R.integer.config_screenBrightnessSettingMinimum); 346 } 347 348 /** 349 * Gets the maximum supported screen brightness setting. 350 * The screen may be allowed to become dimmer than this value but 351 * this is the maximum value that can be set by the user. 352 * @hide 353 */ 354 public int getMaximumScreenBrightnessSetting() { 355 return mContext.getResources().getInteger( 356 com.android.internal.R.integer.config_screenBrightnessSettingMaximum); 357 } 358 359 /** 360 * Gets the default screen brightness setting. 361 * @hide 362 */ 363 public int getDefaultScreenBrightnessSetting() { 364 return mContext.getResources().getInteger( 365 com.android.internal.R.integer.config_screenBrightnessSettingDefault); 366 } 367 368 /** 369 * Returns true if the screen auto-brightness adjustment setting should 370 * be available in the UI. This setting is experimental and disabled by default. 371 * @hide 372 */ 373 public static boolean useScreenAutoBrightnessAdjustmentFeature() { 374 return SystemProperties.getBoolean("persist.power.useautobrightadj", false); 375 } 376 377 /** 378 * Returns true if the twilight service should be used to adjust screen brightness 379 * policy. This setting is experimental and disabled by default. 380 * @hide 381 */ 382 public static boolean useTwilightAdjustmentFeature() { 383 return SystemProperties.getBoolean("persist.power.usetwilightadj", false); 384 } 385 386 /** 387 * Creates a new wake lock with the specified level and flags. 388 * <p> 389 * The {@code levelAndFlags} parameter specifies a wake lock level and optional flags 390 * combined using the logical OR operator. 391 * </p><p> 392 * The wake lock levels are: {@link #PARTIAL_WAKE_LOCK}, 393 * {@link #FULL_WAKE_LOCK}, {@link #SCREEN_DIM_WAKE_LOCK} 394 * and {@link #SCREEN_BRIGHT_WAKE_LOCK}. Exactly one wake lock level must be 395 * specified as part of the {@code levelAndFlags} parameter. 396 * </p><p> 397 * The wake lock flags are: {@link #ACQUIRE_CAUSES_WAKEUP} 398 * and {@link #ON_AFTER_RELEASE}. Multiple flags can be combined as part of the 399 * {@code levelAndFlags} parameters. 400 * </p><p> 401 * Call {@link WakeLock#acquire() acquire()} on the object to acquire the 402 * wake lock, and {@link WakeLock#release release()} when you are done. 403 * </p><p> 404 * {@samplecode 405 * PowerManager pm = (PowerManager)mContext.getSystemService( 406 * Context.POWER_SERVICE); 407 * PowerManager.WakeLock wl = pm.newWakeLock( 408 * PowerManager.SCREEN_DIM_WAKE_LOCK 409 * | PowerManager.ON_AFTER_RELEASE, 410 * TAG); 411 * wl.acquire(); 412 * // ... do work... 413 * wl.release(); 414 * } 415 * </p><p> 416 * Although a wake lock can be created without special permissions, 417 * the {@link android.Manifest.permission#WAKE_LOCK} permission is 418 * required to actually acquire or release the wake lock that is returned. 419 * </p><p class="note"> 420 * If using this to keep the screen on, you should strongly consider using 421 * {@link android.view.WindowManager.LayoutParams#FLAG_KEEP_SCREEN_ON} instead. 422 * This window flag will be correctly managed by the platform 423 * as the user moves between applications and doesn't require a special permission. 424 * </p> 425 * 426 * @param levelAndFlags Combination of wake lock level and flag values defining 427 * the requested behavior of the WakeLock. 428 * @param tag Your class name (or other tag) for debugging purposes. 429 * 430 * @see WakeLock#acquire() 431 * @see WakeLock#release() 432 * @see #PARTIAL_WAKE_LOCK 433 * @see #FULL_WAKE_LOCK 434 * @see #SCREEN_DIM_WAKE_LOCK 435 * @see #SCREEN_BRIGHT_WAKE_LOCK 436 * @see #ACQUIRE_CAUSES_WAKEUP 437 * @see #ON_AFTER_RELEASE 438 */ 439 public WakeLock newWakeLock(int levelAndFlags, String tag) { 440 validateWakeLockParameters(levelAndFlags, tag); 441 return new WakeLock(levelAndFlags, tag, mContext.getOpPackageName()); 442 } 443 444 /** @hide */ 445 public static void validateWakeLockParameters(int levelAndFlags, String tag) { 446 switch (levelAndFlags & WAKE_LOCK_LEVEL_MASK) { 447 case PARTIAL_WAKE_LOCK: 448 case SCREEN_DIM_WAKE_LOCK: 449 case SCREEN_BRIGHT_WAKE_LOCK: 450 case FULL_WAKE_LOCK: 451 case PROXIMITY_SCREEN_OFF_WAKE_LOCK: 452 case DOZE_WAKE_LOCK: 453 break; 454 default: 455 throw new IllegalArgumentException("Must specify a valid wake lock level."); 456 } 457 if (tag == null) { 458 throw new IllegalArgumentException("The tag must not be null."); 459 } 460 } 461 462 /** 463 * Notifies the power manager that user activity happened. 464 * <p> 465 * Resets the auto-off timer and brightens the screen if the device 466 * is not asleep. This is what happens normally when a key or the touch 467 * screen is pressed or when some other user activity occurs. 468 * This method does not wake up the device if it has been put to sleep. 469 * </p><p> 470 * Requires the {@link android.Manifest.permission#DEVICE_POWER} permission. 471 * </p> 472 * 473 * @param when The time of the user activity, in the {@link SystemClock#uptimeMillis()} 474 * time base. This timestamp is used to correctly order the user activity request with 475 * other power management functions. It should be set 476 * to the timestamp of the input event that caused the user activity. 477 * @param noChangeLights If true, does not cause the keyboard backlight to turn on 478 * because of this event. This is set when the power key is pressed. 479 * We want the device to stay on while the button is down, but we're about 480 * to turn off the screen so we don't want the keyboard backlight to turn on again. 481 * Otherwise the lights flash on and then off and it looks weird. 482 * 483 * @see #wakeUp 484 * @see #goToSleep 485 */ 486 public void userActivity(long when, boolean noChangeLights) { 487 try { 488 mService.userActivity(when, USER_ACTIVITY_EVENT_OTHER, 489 noChangeLights ? USER_ACTIVITY_FLAG_NO_CHANGE_LIGHTS : 0); 490 } catch (RemoteException e) { 491 } 492 } 493 494 /** 495 * Forces the device to go to sleep. 496 * <p> 497 * Overrides all the wake locks that are held. 498 * This is what happens when the power key is pressed to turn off the screen. 499 * </p><p> 500 * Requires the {@link android.Manifest.permission#DEVICE_POWER} permission. 501 * </p> 502 * 503 * @param time The time when the request to go to sleep was issued, in the 504 * {@link SystemClock#uptimeMillis()} time base. This timestamp is used to correctly 505 * order the go to sleep request with other power management functions. It should be set 506 * to the timestamp of the input event that caused the request to go to sleep. 507 * 508 * @see #userActivity 509 * @see #wakeUp 510 */ 511 public void goToSleep(long time) { 512 try { 513 mService.goToSleep(time, GO_TO_SLEEP_REASON_USER); 514 } catch (RemoteException e) { 515 } 516 } 517 518 /** 519 * Forces the device to wake up from sleep. 520 * <p> 521 * If the device is currently asleep, wakes it up, otherwise does nothing. 522 * This is what happens when the power key is pressed to turn on the screen. 523 * </p><p> 524 * Requires the {@link android.Manifest.permission#DEVICE_POWER} permission. 525 * </p> 526 * 527 * @param time The time when the request to wake up was issued, in the 528 * {@link SystemClock#uptimeMillis()} time base. This timestamp is used to correctly 529 * order the wake up request with other power management functions. It should be set 530 * to the timestamp of the input event that caused the request to wake up. 531 * 532 * @see #userActivity 533 * @see #goToSleep 534 */ 535 public void wakeUp(long time) { 536 try { 537 mService.wakeUp(time); 538 } catch (RemoteException e) { 539 } 540 } 541 542 /** 543 * Forces the device to start napping. 544 * <p> 545 * If the device is currently awake, starts dreaming, otherwise does nothing. 546 * When the dream ends or if the dream cannot be started, the device will 547 * either wake up or go to sleep depending on whether there has been recent 548 * user activity. 549 * </p><p> 550 * Requires the {@link android.Manifest.permission#DEVICE_POWER} permission. 551 * </p> 552 * 553 * @param time The time when the request to nap was issued, in the 554 * {@link SystemClock#uptimeMillis()} time base. This timestamp is used to correctly 555 * order the nap request with other power management functions. It should be set 556 * to the timestamp of the input event that caused the request to nap. 557 * 558 * @see #wakeUp 559 * @see #goToSleep 560 * 561 * @hide 562 */ 563 public void nap(long time) { 564 try { 565 mService.nap(time); 566 } catch (RemoteException e) { 567 } 568 } 569 570 /** 571 * Sets the brightness of the backlights (screen, keyboard, button). 572 * <p> 573 * Requires the {@link android.Manifest.permission#DEVICE_POWER} permission. 574 * </p> 575 * 576 * @param brightness The brightness value from 0 to 255. 577 * 578 * {@hide} 579 */ 580 public void setBacklightBrightness(int brightness) { 581 try { 582 mService.setTemporaryScreenBrightnessSettingOverride(brightness); 583 } catch (RemoteException e) { 584 } 585 } 586 587 /** 588 * Returns true if the specified wake lock level is supported. 589 * 590 * @param level The wake lock level to check. 591 * @return True if the specified wake lock level is supported. 592 * 593 * {@hide} 594 */ 595 public boolean isWakeLockLevelSupported(int level) { 596 try { 597 return mService.isWakeLockLevelSupported(level); 598 } catch (RemoteException e) { 599 return false; 600 } 601 } 602 603 /** 604 * Returns whether the screen is currently on. 605 * <p> 606 * Only indicates whether the screen is on. The screen could be either bright or dim. 607 * </p><p> 608 * {@samplecode 609 * PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE); 610 * boolean isScreenOn = pm.isScreenOn(); 611 * } 612 * </p> 613 * 614 * @return whether the screen is on (bright or dim). 615 */ 616 public boolean isScreenOn() { 617 try { 618 return mService.isScreenOn(); 619 } catch (RemoteException e) { 620 return false; 621 } 622 } 623 624 /** 625 * Reboot the device. Will not return if the reboot is successful. 626 * <p> 627 * Requires the {@link android.Manifest.permission#REBOOT} permission. 628 * </p> 629 * 630 * @param reason code to pass to the kernel (e.g., "recovery") to 631 * request special boot modes, or null. 632 */ 633 public void reboot(String reason) { 634 try { 635 mService.reboot(false, reason, true); 636 } catch (RemoteException e) { 637 } 638 } 639 640 /** 641 * A wake lock is a mechanism to indicate that your application needs 642 * to have the device stay on. 643 * <p> 644 * Any application using a WakeLock must request the {@code android.permission.WAKE_LOCK} 645 * permission in an {@code <uses-permission>} element of the application's manifest. 646 * Obtain a wake lock by calling {@link PowerManager#newWakeLock(int, String)}. 647 * </p><p> 648 * Call {@link #acquire()} to acquire the wake lock and force the device to stay 649 * on at the level that was requested when the wake lock was created. 650 * </p><p> 651 * Call {@link #release()} when you are done and don't need the lock anymore. 652 * It is very important to do this as soon as possible to avoid running down the 653 * device's battery excessively. 654 * </p> 655 */ 656 public final class WakeLock { 657 private int mFlags; 658 private String mTag; 659 private final String mPackageName; 660 private final IBinder mToken; 661 private int mCount; 662 private boolean mRefCounted = true; 663 private boolean mHeld; 664 private WorkSource mWorkSource; 665 private String mHistoryTag; 666 667 private final Runnable mReleaser = new Runnable() { 668 public void run() { 669 release(); 670 } 671 }; 672 673 WakeLock(int flags, String tag, String packageName) { 674 mFlags = flags; 675 mTag = tag; 676 mPackageName = packageName; 677 mToken = new Binder(); 678 } 679 680 @Override 681 protected void finalize() throws Throwable { 682 synchronized (mToken) { 683 if (mHeld) { 684 Log.wtf(TAG, "WakeLock finalized while still held: " + mTag); 685 try { 686 mService.releaseWakeLock(mToken, 0); 687 } catch (RemoteException e) { 688 } 689 } 690 } 691 } 692 693 /** 694 * Sets whether this WakeLock is reference counted. 695 * <p> 696 * Wake locks are reference counted by default. If a wake lock is 697 * reference counted, then each call to {@link #acquire()} must be 698 * balanced by an equal number of calls to {@link #release()}. If a wake 699 * lock is not reference counted, then one call to {@link #release()} is 700 * sufficient to undo the effect of all previous calls to {@link #acquire()}. 701 * </p> 702 * 703 * @param value True to make the wake lock reference counted, false to 704 * make the wake lock non-reference counted. 705 */ 706 public void setReferenceCounted(boolean value) { 707 synchronized (mToken) { 708 mRefCounted = value; 709 } 710 } 711 712 /** 713 * Acquires the wake lock. 714 * <p> 715 * Ensures that the device is on at the level requested when 716 * the wake lock was created. 717 * </p> 718 */ 719 public void acquire() { 720 synchronized (mToken) { 721 acquireLocked(); 722 } 723 } 724 725 /** 726 * Acquires the wake lock with a timeout. 727 * <p> 728 * Ensures that the device is on at the level requested when 729 * the wake lock was created. The lock will be released after the given timeout 730 * expires. 731 * </p> 732 * 733 * @param timeout The timeout after which to release the wake lock, in milliseconds. 734 */ 735 public void acquire(long timeout) { 736 synchronized (mToken) { 737 acquireLocked(); 738 mHandler.postDelayed(mReleaser, timeout); 739 } 740 } 741 742 private void acquireLocked() { 743 if (!mRefCounted || mCount++ == 0) { 744 // Do this even if the wake lock is already thought to be held (mHeld == true) 745 // because non-reference counted wake locks are not always properly released. 746 // For example, the keyguard's wake lock might be forcibly released by the 747 // power manager without the keyguard knowing. A subsequent call to acquire 748 // should immediately acquire the wake lock once again despite never having 749 // been explicitly released by the keyguard. 750 mHandler.removeCallbacks(mReleaser); 751 try { 752 mService.acquireWakeLock(mToken, mFlags, mTag, mPackageName, mWorkSource, 753 mHistoryTag); 754 } catch (RemoteException e) { 755 } 756 mHeld = true; 757 } 758 } 759 760 /** 761 * Releases the wake lock. 762 * <p> 763 * This method releases your claim to the CPU or screen being on. 764 * The screen may turn off shortly after you release the wake lock, or it may 765 * not if there are other wake locks still held. 766 * </p> 767 */ 768 public void release() { 769 release(0); 770 } 771 772 /** 773 * Releases the wake lock with flags to modify the release behavior. 774 * <p> 775 * This method releases your claim to the CPU or screen being on. 776 * The screen may turn off shortly after you release the wake lock, or it may 777 * not if there are other wake locks still held. 778 * </p> 779 * 780 * @param flags Combination of flag values to modify the release behavior. 781 * Currently only {@link #WAIT_FOR_PROXIMITY_NEGATIVE} is supported. 782 * 783 * {@hide} 784 */ 785 public void release(int flags) { 786 synchronized (mToken) { 787 if (!mRefCounted || --mCount == 0) { 788 mHandler.removeCallbacks(mReleaser); 789 if (mHeld) { 790 try { 791 mService.releaseWakeLock(mToken, flags); 792 } catch (RemoteException e) { 793 } 794 mHeld = false; 795 } 796 } 797 if (mCount < 0) { 798 throw new RuntimeException("WakeLock under-locked " + mTag); 799 } 800 } 801 } 802 803 /** 804 * Returns true if the wake lock has been acquired but not yet released. 805 * 806 * @return True if the wake lock is held. 807 */ 808 public boolean isHeld() { 809 synchronized (mToken) { 810 return mHeld; 811 } 812 } 813 814 /** 815 * Sets the work source associated with the wake lock. 816 * <p> 817 * The work source is used to determine on behalf of which application 818 * the wake lock is being held. This is useful in the case where a 819 * service is performing work on behalf of an application so that the 820 * cost of that work can be accounted to the application. 821 * </p> 822 * 823 * @param ws The work source, or null if none. 824 */ 825 public void setWorkSource(WorkSource ws) { 826 synchronized (mToken) { 827 if (ws != null && ws.size() == 0) { 828 ws = null; 829 } 830 831 final boolean changed; 832 if (ws == null) { 833 changed = mWorkSource != null; 834 mWorkSource = null; 835 } else if (mWorkSource == null) { 836 changed = true; 837 mWorkSource = new WorkSource(ws); 838 } else { 839 changed = mWorkSource.diff(ws); 840 if (changed) { 841 mWorkSource.set(ws); 842 } 843 } 844 845 if (changed && mHeld) { 846 try { 847 mService.updateWakeLockWorkSource(mToken, mWorkSource); 848 } catch (RemoteException e) { 849 } 850 } 851 } 852 } 853 854 /** @hide */ 855 public void setTag(String tag) { 856 mTag = tag; 857 } 858 859 /** @hide */ 860 public void setHistoryTag(String tag) { 861 mHistoryTag = tag; 862 } 863 864 /** @hide */ 865 public void setUnimportantForLogging(boolean state) { 866 if (state) mFlags |= UNIMPORTANT_FOR_LOGGING; 867 else mFlags &= ~UNIMPORTANT_FOR_LOGGING; 868 } 869 870 @Override 871 public String toString() { 872 synchronized (mToken) { 873 return "WakeLock{" 874 + Integer.toHexString(System.identityHashCode(this)) 875 + " held=" + mHeld + ", refCount=" + mCount + "}"; 876 } 877 } 878 } 879} 880