protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.button_layuout);

        final IntentFilter filter = new IntentFilter();
        // 螢幕滅屏廣播
        filter.addAction(Intent.ACTION_SCREEN_OFF);
        // 螢幕亮屏廣播
        filter.addAction(Intent.ACTION_SCREEN_ON);
        // 螢幕解鎖廣播
        filter.addAction(Intent.ACTION_USER_PRESENT);
        // 當長按電源鍵彈出“關機”對話或者鎖屏時系統會發出這個廣播
        // example：有時候會用到系統對話方塊，許可權可能很高，會覆蓋在鎖屏介面或者“關機”對話方塊之上，
        // 所以監聽這個廣播，當收到時就隱藏自己的對話，如點選pad右下角部分彈出的對話方塊 
        filter.addAction(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);

        BroadcastReceiver mBatInfoReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(final Context context, final Intent intent) {
                Log.d(TAG, "onReceive");
                String action = intent.getAction();

                if (Intent.ACTION_SCREEN_ON.equals(action)) {
                    Log.d(TAG, "screen on");
                } else if (Intent.ACTION_SCREEN_OFF.equals(action)) {
                    Log.d(TAG, "screen off");
                } else if (Intent.ACTION_USER_PRESENT.equals(action)) {
                    Log.d(TAG, "screen unlock");
                } else if (Intent.ACTION_CLOSE_SYSTEM_DIALOGS.equals(intent.getAction())) {
                    Log.i(TAG, " receive Intent.ACTION_CLOSE_SYSTEM_DIALOGS");
                }
            }
        };
        Log.d(TAG, "registerReceiver");
        registerReceiver(mBatInfoReceiver, filter);
    }