Is it possible to determine whether an Android device is plugged into a computer or just power?

I was wondering if it was possible to specifically determine if an Android device was plugged into a computer or just power.

The main reason is I'd like for my phone to "Stay Awake" when it's plugged into a computer while I'm developing, but not when it's plugged into a power outlet a night.

I was thinking that if I could tell what I'm connect开发者_如何学JAVAed to, I could use ACTION_POWER_CONNECTED to start up a service and check what USB I'm connected to.

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First you need to register a receiver to listen to Intent.ACTION_BATTERY_CHANGED and check for the BatteryManager.BATTERY_PLUGGED_USB. Below is the code to do so:

BroadcastReceiver receiver = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        int plugged = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
        if (plugged == BatteryManager.BATTERY_PLUGGED_USB) {
            Toast.makeText(getApplicationContext(), "Connected to USB, Stay Awake", Toast.LENGTH_LONG).show();
            PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
            PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK, "WakeLock");
            wl.acquire();
        } 
    }
};

// register the receiver to listen to battery change
IntentFilter filter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
registerReceiver(receiver, filter);

You also need the permission in your AndroidManifest.xml to enable staying awake

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

One other note, at some point you will need to unregister the receiver. You could provide that via settings page to call unregisterReceiver

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I actually found the exact way to choose whether to keep the screen on when plugged into AC, USB or either by looking into the source at http://google.com/codesearch#409TP6F96yI/src/com/android/settings/DevelopmentSettings.java&l=95

Requires permission: android.permission.WRITE_SETTINGS

Settings.System.putInt(getContentResolver(), Settings.System.STAY_ON_WHILE_PLUGGED_IN,
                mKeepScreenOn.isChecked() ?
                (BatteryManager.BATTERY_PLUGGED_AC | BatteryManager.BATTERY_PLUGGED_USB) : 0);

For AC: BatteryManager.BATTERY_PLUGGED_AC

For USB: BatteryManager.BATTERY_PLUGGED_USB

For Either: (BatteryManager.BATTERY_PLUGGED_AC | BatteryManager.BATTERY_PLUGGED_USB)

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Well, if it's connected to the power supply and you want it to go to sleep just short press the POWER button.