Android开发人员选项->保持清醒== FLAG_KEEP_SCREEN_ON或WAKE_LOCK？

Question

I am building an app on an Android Nexus 10 tablet and it will serve as a kiosk, so I would like the screen to be on 100% of the time. I've been currently using Developer Options > Stay Awake (screen will ever sleep while charging).

Per this documentation: https://developer.android.com/training/scheduling/wakelock

When this setting is enabled, is it equivalent to WAKE_LOCK or merely FLAG_KEEP_SCREEN_ON?

Thanks!

Answer 1

No, it's more low-level than that. The "Stay Awake" toggle puts a value in Settings.Global, which is then read by the PowerManagerService. That value is a combination of the different plug-types that could be charging the phone (the switch uses AC, USB and WIRELESS by default).

If the stored value isn't 0 , and the device is plugged into one of the plug types specified by that value, the PowerManagerService just never sets the device to the ASLEEP state.

It's similar to a wakelock, but it has its own special process.

StayAwakePreferenceController PowerManagerService

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By the way, FLAG_KEEP_SCREEN_ON actually uses a wakelock behind the scenes. You just don't need to hold the WAKELOCK permission to use it.

You can see that here and here .

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For a kiosk-type thing, you should probably use FLAG_KEEP_SCREEN_ON. This wakelock prevents the screen from dimming, while the "Stay Awake" toggle doesn't.