Android: 如何以编程方式打开和关闭屏幕？

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Are you sure you requested the proper permission in your Manifest file?

<uses-permission android:name="android.permission.WAKE_LOCK" />

You can use the AlarmManager1 class to fire off an intent that starts your activity and acquires the wake lock. This will turn on the screen and keep it on. Releasing the wakelock will allow the device to go to sleep on its own.

You can also take a look at using the PowerManager to set the device to sleep: http://developer.android.com/reference/android/os/PowerManager.html#goToSleep(long)

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I wouldn't have hope of "waking the screen" in the activity. If the screen is off the activity is probably in a paused state and shouldn't be running any code.

When waking up, there is the issue of the lockscreen. I don't know how any app can automatically bypass the lockscreen.

You should consider running your background tasks in a service, and then using the notification manager to send a notification when whatever is detected. The notification should provide some sort of device alert (screen wake up, notification icon, notification led, etc). When clicking the notification it can launch the intent to start your activity.

You could also attempt to start the activity direct from the service, but I really don't know if that will turn the screen on or bypass the lockscreen.

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I am going to assume you only want this to be in effect while your application is in the foreground.

This code:

params.flags |= LayoutParams.FLAG_KEEP_SCREEN_ON;
params.screenBrightness = 0;
getWindow().setAttributes(params);

Does not turn the screen off in the traditional sense. It makes the screen as dim as possible. In the standard platform there is a limit to how dim it can be; if your device is actually allowing the screen to turn completely off, then it is some peculiarity of the implementation of that device and not a behavior you can count on across devices.

In fact using this in conjunction with FLAG_KEEP_SCREEN_ON means that you will never allow the screen to go off (and thus the device to go into low-power mode) even if the particular device is allowing you to set the screen brightness to full-off. Keep this very strongly in mind. You will be using much more power than you would if the screen was really off.

Now for turning the screen back to regular brightness, just setting the brightness value should do it:

WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = -1;
getWindow().setAttributes(params);

I can't explain why this wouldn't replace the 0 value you had previously set. As a test, you could try putting a forced full brightness in there to force to that specific brightness:

WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = 1;
getWindow().setAttributes(params);

This definitely works. For example, Google's Books apps uses this to allow you to set the screen brightness to dim while using a book and then return to regular brightness when turning that off.

To help debug, you can use "adb shell dumpsys window" to see the current state of your window. In the data for your window, it will tell you the current LayoutParams that have been set for it. Ensure the value you think is actually there.

And again, FLAG_KEEP_SCREEN_ON is a separate concept; it and the brightness have no direct impact on each other. (And there would be no reason to set the flag again when undoing the brightness, if you had already set it when putting the brightness to 0. The flag will stay set until you change it.)

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I had written this method to turn on the screen after screen lock. It works perfectly for me. Try it-

    private void unlockScreen() {
Window window = this.getWindow();
window.addFlags(WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
window.addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED);
window.addFlags(WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
}

And call this method from onResume().

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I would suggest this one:

PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "tag");
wl.acquire();

The flag ACQUIRE_CAUSES_WAKEUP is explained like that:

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.

Also, make sure you have the following permission in the AndroidManifewst.xml file:

<uses-permission android:name="android.permission.WAKE_LOCK" />

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Here is a successful example of an implementation of the same thing, on a device which supported lower screen brightness values (I tested on an Allwinner Chinese 7" tablet running API15).

WindowManager.LayoutParams params = this.getWindow().getAttributes();


/** Turn off: */
params.flags = WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
//TODO Store original brightness value
params.screenBrightness = 0.1f;
this.getWindow().setAttributes(params);


/** Turn on: */
params.flags = WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
//TODO restoring from original value
params.screenBrightness = 0.9f;
this.getWindow().setAttributes(params);

If someone else tries this out, pls comment below if it worked/didn't work and the device, Android API.

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Hi I hope this will help:

 private PowerManager mPowerManager;
private PowerManager.WakeLock mWakeLock;


public void turnOnScreen(){
// turn on screen
Log.v("ProximityActivity", "ON!");
mWakeLock = mPowerManager.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "tag");
mWakeLock.acquire();
}


@TargetApi(21) //Suppress lint error for PROXIMITY_SCREEN_OFF_WAKE_LOCK
public void turnOffScreen(){
// turn off screen
Log.v("ProximityActivity", "OFF!");
mWakeLock = mPowerManager.newWakeLock(PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK, "tag");
mWakeLock.acquire();
}

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     WakeLock screenLock =    ((PowerManager)getSystemService(POWER_SERVICE)).newWakeLock(
PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "TAG");
screenLock.acquire();


//later
screenLock.release();

//User Manifest file

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Regarding to Android documentation it can be achieve by using following code line:

getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

I have added this in my onCreate method and it works fine.

On the link you will find different ways to achieve this and general explanation as well.

Link to the documenation: https://developer.android.com/training/scheduling/wakelock.html

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The best way to do it ( using rooted devices) :

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
.
.
.


int flags = WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD | WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON;
getWindow().addFlags(flags); // this is how your app will wake up the screen
//you will call this activity later


.
.
.
}

Now we have this two functions:

private void turnOffScreen(){


try{
Class c = Class.forName("android.os.PowerManager");
PowerManager  mPowerManager = (PowerManager) this.getSystemService(Context.POWER_SERVICE);
for(Method m : c.getDeclaredMethods()){
if(m.getName().equals("goToSleep")){
m.setAccessible(true);
if(m.getParameterTypes().length == 1){
m.invoke(mPowerManager,SystemClock.uptimeMillis()-2);
}
}
}
} catch (Exception e){
}
}

And this:

public void turnOnScreen(){
Intent i = new Intent(this,YOURACTIVITYWITHFLAGS.class);
startActivity(i);
}

Sorry for my bad english.

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To keep screen on:

getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

Back to screen default mode: just clear the flag FLAG_KEEP_SCREEN_ON

getWindow().clearFlags(android.view.WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

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This is worked on Marshmallow

private final String TAG = "OnOffScreen";
private PowerManager _powerManager;
private PowerManager.WakeLock _screenOffWakeLock;


public void turnOnScreen() {
if (_screenOffWakeLock != null) {
_screenOffWakeLock.release();
}
}


public void turnOffScreen() {
try {
_powerManager = (PowerManager) this.getSystemService(POWER_SERVICE);
if (_powerManager != null) {
_screenOffWakeLock = _powerManager.newWakeLock(PROXIMITY_SCREEN_OFF_WAKE_LOCK, TAG);
if (_screenOffWakeLock != null) {
_screenOffWakeLock.acquire();
}
}
} catch (Exception ex) {
ex.printStackTrace();
}
}

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If your app is a system app,you can use PowerManager.goToSleep() to turn screen off,you requires a special permission

before you use goToSleep(), you need use reflection just like:

public static void goToSleep(Context context) {
PowerManager powerManager= (PowerManager)context.getSystemService(Context.POWER_SERVICE);
try {
powerManager.getClass().getMethod("goToSleep", new Class[]{long.class}).invoke(powerManager, SystemClock.uptimeMillis());
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
} catch (NoSuchMethodException e) {
e.printStackTrace();
}
}

Now,you can use goToSleep() to turn screen off.

This is what happens when the power key is pressed to turn off the screen.

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Simply add

android:keepScreenOn="true"

or call

setKeepScreenOn(true)

on parent view.

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As per Android API 28 and above you need to do the following to turn on the screen

setShowWhenLocked(true);
setTurnScreenOn(true);
KeyguardManager keyguardManager = (KeyguardManager)
getSystemService(Context.KEYGUARD_SERVICE);
keyguardManager.requestDismissKeyguard(this, null);

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I have tried all above solution but none worked for me. so I googled and found below solutions. I tried and it worked.

https://www.tutorialspoint.com/how-to-turn-android-device-screen-on-and-off-programmatically

if there is any suggestion then please give