Android中长按Power键默认会弹出对话框让用户选择“飞行模式”，“静音”，“关机”等功能,弹出对话框的代码位于： frameworks\policies\base\phone\com\android\internal\policy\impl\PhoneWindowManager.java

private final Runnable mPowerLongPress = new Runnable() {
    public void run() {
        // The context isn't read
        if (mLongPressOnPowerBehavior < 0) {
            mLongPressOnPowerBehavior = mContext.getResources().getInteger(
                    com.android.internal.R.integer.config_longPressOnPowerBehavior);
        }
        switch (mLongPressOnPowerBehavior) {
        case LONG_PRESS_POWER_NOTHING:
            break;
        case LONG_PRESS_POWER_GLOBAL_ACTIONS:
            mPowerKeyHandled = true;
            performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false);
            sendCloseSystemWindows(SYSTEM_DIALOG_REASON_GLOBAL_ACTIONS);
            showGlobalActionsDialog();
            break;
        case LONG_PRESS_POWER_SHUT_OFF:
            mPowerKeyHandled = true;
            performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false);
            sendCloseSystemWindows(SYSTEM_DIALOG_REASON_GLOBAL_ACTIONS);
            ShutdownThread.shutdown(mContext, true);
            break;
        }
    }
};

void showGlobalActionsDialog() {
    if (mGlobalActions == null) {
        mGlobalActions = new GlobalActions(mContext);
    }
    final boolean keyguardShowing = mKeyguardMediator.isShowingAndNotHidden();
    mGlobalActions.showDialog(keyguardShowing, isDeviceProvisioned());
    if (keyguardShowing) {
        // since it took two seconds of long press to bring this up,
        // poke the wake lock so they have some time to see the dialog.
        mKeyguardMediator.pokeWakelock();
    }
}