如何使用PowerManager和PARTIAL_WAKE_LOCK

Question

I develop a small app, this one have to run always over all when the device is sleep or deep sleep (press right button to turn off the screen) I read many posts about it, and all tell me that the way is use PowerManager, and my question is if I use fine this command, my structure is> myActivity.class, ReceiverBoot.class and ServiceBoot.class, I use the POwerManager class on myActivity.class like this:

PowerManager mgr = (PowerManager)this.getSystemService(Context.POWER_SERVICE);
PowerManager wakeLock = mgr.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP , "MyWakeLock");

on onCreateMethod after of this one put

wakeLock.acquire();

and after of this one I have a

super.onCreate(savedInstanceState);
this.mTimer.scheduleAtFixedRate(
                new TimerTask(){
                    @Override
                    public void run(){doTask();}
                } , 0, 1000);

wakeLock.release();

on Manifest XML code I have

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

and on layout XML code have

android:keepScreenOn="true"

but after to 10seg the creen es OFF always but the app is running, jut with wifi.

the app work very fine with wifi conn, but when change to 3G conn, the app is gone, I use fine this command?? the problem is the kind of conn to Internet??? thanks a lot!

Answer 1

I'm not 100% clear on your issue. Whether its the data issue, or the screen issue. (Or if the screen issue is what you are doing to try and fix the data issue?).

For the screen

You are not using the right lock to keep the screen on. PARTIAL_WAKE_LOCK only requests that you can use the processor. To keep the screen on your app use one of SCREEN_DIM_WAKE_LOCK , SCREEN_BRIGHT_WAKE_LOCK or FULL_WAKE_LOCK depending on what you want. This lock should be held for as long as you need the lock. Currently you are releasing it in onCreate(). Keep in mind that if the user presses the power button though that your lock is released (with PARTIAL being the exception to this).

If your intent is just to keep the screen on when a view is active then it's better not to use the lock at all. The wake lock needs an extra permission. You can do it by adding this to your onCreate override:

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

This is the same effect as using android:keepScreenOn="true" , which you already seem to be doing. I can't however tell why that isn't working from your snippets. Make sure you are inflating the right layout.

For your data

The device will likely be switching off 3G data when the screen is not active (and no lock is present). Again, don't release your lock if you need it (Though don't keep it forever either, that's just going to suck up phone battery).