| This class gives you control of the power state of the device.
Device battery life will be significantly affected by the use of this API. Do not
acquire WakeLocks unless you really need them, use the minimum levels possible, and be sure
to release it as soon as you can.
You can obtain an instance of this class by calling
{@link android.content.Context#getSystemService(java.lang.String) Context.getSystemService()}.
The primary API you'll use is {@link #newWakeLock(int, String) newWakeLock()}. This will
create a {@link PowerManager.WakeLock} object. You can then use methods on this object to
control the power state of the device. In practice it's quite simple:
{@samplecode
PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "My Tag");
wl.acquire();
..screen will stay on during this section..
wl.release();
}
The following flags are defined, with varying effects on system power. These flags are
mutually exclusive - you may only specify one of them.
| Flag Value |
CPU | Screen | Keyboard |
|---|
| {@link #PARTIAL_WAKE_LOCK} |
On* | Off | Off |
|---|
| {@link #SCREEN_DIM_WAKE_LOCK} |
On | Dim | Off |
|---|
| {@link #SCREEN_BRIGHT_WAKE_LOCK} |
On | Bright | Off |
|---|
| {@link #FULL_WAKE_LOCK} |
On | Bright | Bright |
|---|
*If you hold a partial wakelock, the CPU will continue to run, irrespective of any timers
and even after the user presses the power button. In all other wakelocks, the CPU will run, but
the user can still put the device to sleep using the power button.
In addition, you can add two more flags, which affect behavior of the screen only. These
flags have no effect when combined with a {@link #PARTIAL_WAKE_LOCK}.
| Flag Value | Description |
|---|
| {@link #ACQUIRE_CAUSES_WAKEUP} |
Normal wake locks don't actually turn on the illumination. Instead, they cause
the illumination to remain on once it turns on (e.g. from user activity). This flag
will force the screen and/or keyboard to turn on immediately, when the WakeLock is
acquired. A typical use would be for notifications which are important for the user to
see immediately. |
|---|
| {@link #ON_AFTER_RELEASE} |
If this flag is set, the user activity timer will be reset when the WakeLock is
released, causing the illumination to remain on a bit longer. This can be used to
reduce flicker if you are cycling between wake lock conditions. |
|---|
| 