android屏幕唤醒锁定时如何通过音量按钮打开闪光灯？

Question

hi guys i am developing an app in which i want to open the camera flash light through volume button when phone in wake lock screen state or display is off. i am also do this through service class and broadcast receiver but not right output. i think anyone understand my problem. is Anybody have solution so please help me. Thanks in Advances. i am using this code app work properly but i want to do this when phone in wake-lock state or display is off.

public boolean dispatchKeyEvent(KeyEvent event) {
    int action = event.getAction();
    int keyCode = event.getKeyCode();

        switch (keyCode) {
        case KeyEvent.KEYCODE_VOLUME_UP:
            if (action == KeyEvent.ACTION_DOWN) {
                count++;
                if(count==2){

                    Parameters p = camera.getParameters();
                    p.setFlashMode(Parameters.FLASH_MODE_TORCH);
                    camera.setParameters(p);
                    camera.startPreview();
                    isFlashOn = true;
                    count=0;
                    Log.e("error", "App is crashed here");  
                }

            }
           return  isFlashOn;
        case KeyEvent.KEYCODE_VOLUME_DOWN:
            if (action == KeyEvent.ACTION_DOWN) {
                counter--;
                if(counter==0){

                    Parameters p = camera.getParameters();
                    p.setFlashMode(Parameters.FLASH_MODE_OFF);
                    camera.setParameters(p);
                    camera.stopPreview();
                    isFlashOn = false;
                    counter=2;
                }

            }
            return isFlashOn = false ;
        default:
           return super.dispatchKeyEvent(event);
        }
    }

Answer 1

When screen is off, volume buttons are only active when there's music playing, otherwise there no method to know if they are pressed. So you can play a silent song when screen is off and use whatever method you can find (onKeyDown, dispatchKeyEvent, or use broadcast receiver) but the battery will drain faster.