Android merchant scans the code gun to read the QR code of mobile phone

public class ScanGunKeyEventHelper {
 
    private final static long MESSAGE_DELAY = 500;             //Depend 500ms, determine whether the scanning code is completed.    private StringBuffer mStringBufferResult;                  //Scan the QR code content    private boolean mCaps;                                     //Case difference    private final Handler mHandler;
    private final BluetoothAdapter mBluetoothAdapter;
    private final Runnable mScanningFishedRunnable;
    private OnScanSuccessListener mOnScanSuccessListener;
    private String mDeviceName;
 
    public ScanGunKeyEventHelper(OnScanSuccessListener onScanSuccessListener) {
        mOnScanSuccessListener = onScanSuccessListener ;
        mBluetoothAdapter = ();
        mStringBufferResult = new StringBuffer();
        mHandler = new Handler();
        mScanningFishedRunnable = new Runnable() {
            @Override
            public void run() {
                performScanSuccess();
            }
        };
    }
 
 
    /**
      * Return the result after the code is successfully scanned
      */
    private void performScanSuccess() {
        String barcode = ();
        if (mOnScanSuccessListener != null)
            (barcode);
        (0);
    }
 
 
    /**
      * Analysis of QR code scan gun incident
      * @param event
      */
    public void analysisKeyEvent(KeyEvent event) {
 
        int keyCode = ();
 
        //Case judgment of letters        checkLetterStatus(event);
 
        if (() == KeyEvent.ACTION_DOWN) {
 
            char aChar = getInputCode(event);;
 
            if (aChar != 0) {
                (aChar);
            }
 
            if (keyCode == KeyEvent.KEYCODE_ENTER) {
                //If it is the Enter key, return directly                (mScanningFishedRunnable);
                (mScanningFishedRunnable);
            } else {
                //Delay post, if there are other events within 500ms                (mScanningFishedRunnable);
                (mScanningFishedRunnable, MESSAGE_DELAY);
            }
 
        }
    }
    //Check shift key    private void checkLetterStatus(KeyEvent event) {
        int keyCode = ();
        if (keyCode == KeyEvent.KEYCODE_SHIFT_RIGHT || keyCode == KeyEvent.KEYCODE_SHIFT_LEFT) {
            if (() == KeyEvent.ACTION_DOWN) {
                //Press shift key to indicate capitalization                mCaps = true;
            } else {
                //Release shift key to lowercase                mCaps = false;
            }
        }
    }
 
    //Get scanned content    private char getInputCode(KeyEvent event) {
 
        int keyCode = ();
 
        char aChar;
 
        if (keyCode >= KeyEvent.KEYCODE_A && keyCode <= KeyEvent.KEYCODE_Z) {
            //letter            aChar = (char) ((mCaps ? 'A' : 'a') + keyCode - KeyEvent.KEYCODE_A);
        } else if (keyCode >= KeyEvent.KEYCODE_0 && keyCode <= KeyEvent.KEYCODE_9) {
            //number            aChar = (char) ('0' + keyCode - KeyEvent.KEYCODE_0);
        } else {
            //Other symbols            switch (keyCode) {
                case KeyEvent.KEYCODE_PERIOD:
                    aChar = '.';
                    break;
                case KeyEvent.KEYCODE_MINUS:
                    aChar = mCaps ? '_' : '-';
                    break;
                case KeyEvent.KEYCODE_SLASH:
                    aChar = '/';
                    break;
                case KeyEvent.KEYCODE_BACKSLASH:
                    aChar = mCaps ? '|' : '\\';
                    break;
                default:
                    aChar = 0;
                    break;
            }
        }
 
        return aChar;
 
    }
 
    public interface OnScanSuccessListener {
        void onScanSuccess(String barcode);
    }
 
 
    public void onDestroy() {
        (mScanningFishedRunnable);
        mOnScanSuccessListener = null;
    }
 
 
    // Some mobile phones such as Samsung cannot use this method//    private void hasScanGun() {
//        Configuration cfg = getResources().getConfiguration();
//        return  != Configuration.KEYBOARD_NOKEYS;
//    }
 
//    /**
 // * Is the scanner connected?
 // * @return
 // */
//    public boolean hasScanGun() {
//
//        if (mBluetoothAdapter == null) {
//            return false;
//        }
//
//        Set<BluetoothDevice> blueDevices = ();
//
//        if (blueDevices == null || () <= 0) {
//            return false;
//        }
//
//        for (Iterator<BluetoothDevice> iterator = (); (); ) {
//            BluetoothDevice bluetoothDevice = ();
//
//            if (().getMajorDeviceClass() == ) {
//                mDeviceName = ();
//                return isInputDeviceExist(mDeviceName);
//            }
//
//        }
//
//        return false;
//
//    }
 
    /**
      * Whether the input device exists
      * @param deviceName
      * @return
      */
    private boolean isInputDeviceExist(String deviceName) {
        int[] deviceIds = ();
 
        for (int id : deviceIds) {
            if ((id).getName().equals(deviceName)) {
                return true;
            }
        }
        return false;
    }
 
    /**
      * Is it a QR code scan gun event (the name obtained by some models KeyEvent is incorrect)
      * @param event
      * @return
      */
    @Deprecated
    public boolean isScanGunEvent(KeyEvent event) {
        return ().getName().equals(mDeviceName);
    }
 
}

 //Implement the above-mentioned interface'public class MainActivity extends AppCompatActivity implements
        
//Rewrite the code scan gun to recognize and return data@Override
       public void onScanSuccess(String barcode) {
 
        barCode = barcode;
        if (barcode != null && recordPrice > 0 && 
                ("readyPay")) {
            payDishs();
        }
    }
 
//Rewrite and capture the scan gun incident    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
 
    (event);
        return true;
    }