Develop Reference

turn on screen from service

I have Android 7 (API 24). I launch my app which launches started service. Then timeout causes screen to turn off. The service does something in background and eventually wants to turn the screen back on. How can I turn the screen on from service?
I already tried:
PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "MyApp::MyWakelockTag");
wl.acquire();
The permission for WAKE_LOCK was set. I also wanted to use FULL_WAKE_LOCK flag, but this is deprecated. Anyway, this doesn't work.
I also tried to launch my activity from service and implement this in OnResume of my activity:
getWindow().addFlags(WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
This also doesn't work (i.e. it doesn't turn the screen on).
Thank you for your help.

How to keep Android awake in background when screen is off

I runs web server in my rooted Android Tablet. I setup it for web development. I created a home network by this Android server. but when the screen of the tab turns off, the server also stop working & again start working when i turn on the screen. but its not possible to turn on the screen for long time. I can be harmful for my tablet. Is there any way to keep awake my tablet when the screen is turn off so that my server can work properly in Background.
please help

You can run a service in the background and acquire lock like this :
PowerManager powerManager = (PowerManager) getSystemService(POWER_SERVICE);
WakeLock wakeLock = powerManager.newWakeLock(PowerManager.FULL_WAKE_LOCK,
"MyWakelockTag");
wakeLock.acquire();
and return onStartCommand START_STICKY. To release the wake lock, call wakelock.release().
Do not forget to put the permission in the manifest file :
<uses-permission android:name="android.permission.WAKE_LOCK" />
Or you can use this app to prevent phone from sleeping :
https://play.google.com/store/apps/details?id=nl.syntaxa.caffeine

Detect phone movement when screen is off

I am developing an application which should detect user movement and when he stops for more than 5 minutes it should sound an alarm. I was able to detect movement with accelerometer but the problem is it doesnt work when the screen is off. I have also tried using partial wakeLock. Re-registering accelerometer doesnt work either (this should be workaround for motorola devices).
Maybe I can do this using GPS and sound an alarm when GPS speed is less than 1m/s for more than 5 minutes but I am not sure if I will receive GPS updates when screen is off.
So I need a solution that will detect user movement even is screen is off on most devices. Any ideas on how to acomplish this?
Thanks in forward

You should acquire a partial wake lock for this kind of operation. Use the PowerManager class.
Something like this:
PowerManager pm = (PowerManager)getSystemService(POWER_SERVICE);
PowerManager.WakeLock lock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "SensorRead");
lock.acquire();
You need also this permission in the AndroidManifest.xml:
<uses-permission android:name="android.permission.WAKE_LOCK" />
Is recommendable using lock.release(); when you're done your work.
EDIT:
Also, this article could be useful for you.

partial wake lock this is what you need to access while your screen is off.
private PowerManager.WakeLock mWakeLock;
PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
mWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "My Tag");
mWakeLock.acquire();
And after you're done, just release the lock:
mWakeLock.release();
If you obtain accelerometer data in a Service, you could simply acquire lock in it's onCreate() and release in onDestroy().

How to avoid user turn off the screen which result in the wifi turned off during downloading

In my application, I use AsyncTask to download large files (300M+). I noticed that when the user turns off their screen (locks their device), the wifi will disconnect and the download will hang.
I wonder if it is possible to avoid this?

You required to implement WakeLock in your application. Wakelock will wake up the CPU incase of screen is off and performs the operations in normal ways.
Write down following code before starting the AsyncTask,
PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK|PowerManager.ACQUIRE_CAUSES_WAKEUP, "bbbb");
wl.acquire();
You need to write wl.release(); on PostExecution() method. And you need to define permission in AndroidManifest.xml as follows,
<uses-permission android:name="android.permission.WAKE_LOCK" />

The common practice in this case is to take a WakeLock to keep the CPU awake, and take a WifiLock to keep the wifi connected, so that your app keeps running even if the screen is turned off.
Don't forget to release the locks when you're done!

Android - Wake Up and Unlock Device

Application description:
The application is intended as a safety program for a specific client (not to be deployed publicly). When the application has not detected movement for a certain period of time, the application should sound an alarm and bring itself to the foreground if it is in the background or the device is asleep.
The problem:
In the event the device is asleep and locked, we need to wake up and unlock the device. Using various techniques found here on SO and other places, we've been able to (partially) wake and unlock the device, however this ONLY behaves properly when the device is physically plugged in to a computer. If the device is sitting by itself unplugged, and we test the wake-unlock, nothing happens; the device seems to remain asleep, and the application seems to do nothing at all (no alarm).
I have used this post about using PowerManager and KeyguardManager, and this post using window flags.
Here is the code presently used to wake the device:
public void wakeDevice() {
PowerManager powerManager = (PowerManager) getSystemService(Context.POWER_SERVICE);
wakeLock = powerManager.newWakeLock((PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.FULL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP), "TAG");
wakeLock.acquire();
KeyguardManager keyguardManager = (KeyguardManager) getSystemService(Context.KEYGUARD_SERVICE);
KeyguardLock keyguardLock = keyguardManager.newKeyguardLock("TAG");
keyguardLock.disableKeyguard();
runOnUiThread(new Runnable(){
public void run(){
getWindow().addFlags(
WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED
| WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON
| WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
| WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
}
});
}
From the comments and posts on some of the other SO questions I've seen / used, it seems as though the PowerManager / KeyguardManager code should have done the trick. Again, as I said before, it does technically work while the device is plugged in via USB to the dev machine, but does absolutely nothing while the device is separated.
Also note this is our first Android application, and so are fully aware we might be completely off on what we are trying to do. Any suggestions are welcome.
So in short, given the code above, why does the device behave so differently based on whether it is plugged in, and what should we change in order to wake and unlock the device as described? Thank you in advance for your assistance!

I solved the issue. The reason we observed different behaviour when the device was plugged in via USB was because the device's CPU was not going to sleep. I assume this is either a result of the debug mode setting, or simply how it behaves when plugged in to a computer since the power-saving feature of CPU-sleeping would be irrelevant. Obviously, when the device is not plugged in, the CPU would happily take a nap, and while we did observe the application randomly running (it would wake itself up at random times), the timing would be inconsistent. I further assume this is because the few CPU cycles that occurred are allocated sparingly, and our application would be given very few cycles at "random" times.
So our solution was to grab a partial wake lock when the device goes into the background (which is done in the onPause method), and release the lock in the onResume method. This seems to prevent the CPU from sleeping. We continue to use the full wake lock and keyguard disable to wake the device when we need to. Using the partial wake lock seems to keep the CPU from sleeping, and the device does appear to wake up properly when expected. Here is our updated code, in case anyone comes across this issue:
// Called from onCreate
protected void createWakeLocks(){
PowerManager powerManager = (PowerManager) getSystemService(Context.POWER_SERVICE);
fullWakeLock = powerManager.newWakeLock((PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.FULL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP), "Loneworker - FULL WAKE LOCK");
partialWakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "Loneworker - PARTIAL WAKE LOCK");
}
// Called implicitly when device is about to sleep or application is backgrounded
protected void onPause(){
super.onPause();
partialWakeLock.acquire();
}
// Called implicitly when device is about to wake up or foregrounded
protected void onResume(){
super.onResume();
if(fullWakeLock.isHeld()){
fullWakeLock.release();
}
if(partialWakeLock.isHeld()){
partialWakeLock.release();
}
}
// Called whenever we need to wake up the device
public void wakeDevice() {
fullWakeLock.acquire();
KeyguardManager keyguardManager = (KeyguardManager) getSystemService(Context.KEYGUARD_SERVICE);
KeyguardLock keyguardLock = keyguardManager.newKeyguardLock("TAG");
keyguardLock.disableKeyguard();
}