public class ScanGunKeyEventHelper {
 
    private final static long MESSAGE_DELAY = 500;             //延遲500ms，判斷掃碼是否完成。
    private StringBuffer mStringBufferResult;                  //掃碼內容
    private boolean mCaps;                                     //大小寫區(qū)分
    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 = BluetoothAdapter.getDefaultAdapter();
        mStringBufferResult = new StringBuffer();
        mHandler = new Handler();
        mScanningFishedRunnable = new Runnable() {
            @Override
            public void run() {
                performScanSuccess();
            }
        };
    }
 
 
    /**
     * 返回掃碼成功后的結果
     */
    private void performScanSuccess() {
        String barcode = mStringBufferResult.toString();
        if (mOnScanSuccessListener != null)
            mOnScanSuccessListener.onScanSuccess(barcode);
        mStringBufferResult.setLength(0);
    }
 
 
    /**
     * 掃碼槍事件解析
     * @param event
     */
    public void analysisKeyEvent(KeyEvent event) {
 
        int keyCode = event.getKeyCode();
 
        //字母大小寫判斷
        checkLetterStatus(event);
 
        if (event.getAction() == KeyEvent.ACTION_DOWN) {
 
            char aChar = getInputCode(event);;
 
            if (aChar != 0) {
                mStringBufferResult.append(aChar);
            }
 
            if (keyCode == KeyEvent.KEYCODE_ENTER) {
                //若為回車鍵，直接返回
                mHandler.removeCallbacks(mScanningFishedRunnable);
                mHandler.post(mScanningFishedRunnable);
            } else {
                //延遲post，若500ms內，有其他事件
                mHandler.removeCallbacks(mScanningFishedRunnable);
                mHandler.postDelayed(mScanningFishedRunnable, MESSAGE_DELAY);
            }
 
        }
    }
    //檢查shift鍵
    private void checkLetterStatus(KeyEvent event) {
        int keyCode = event.getKeyCode();
        if (keyCode == KeyEvent.KEYCODE_SHIFT_RIGHT || keyCode == KeyEvent.KEYCODE_SHIFT_LEFT) {
            if (event.getAction() == KeyEvent.ACTION_DOWN) {
                //按著shift鍵，表示大寫
                mCaps = true;
            } else {
                //松開shift鍵，表示小寫
                mCaps = false;
            }
        }
    }
 
    //獲取掃描內容
    private char getInputCode(KeyEvent event) {
 
        int keyCode = event.getKeyCode();
 
        char aChar;
 
        if (keyCode >= KeyEvent.KEYCODE_A && keyCode <= KeyEvent.KEYCODE_Z) {
            //字母
            aChar = (char) ((mCaps ? 'A' : 'a') + keyCode - KeyEvent.KEYCODE_A);
        } else if (keyCode >= KeyEvent.KEYCODE_0 && keyCode <= KeyEvent.KEYCODE_9) {
            //數(shù)字
            aChar = (char) ('0' + keyCode - KeyEvent.KEYCODE_0);
        } else {
            //其他符號
            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() {
        mHandler.removeCallbacks(mScanningFishedRunnable);
        mOnScanSuccessListener = null;
    }
 
 
    //部分手機如三星，無法使用該方法
//    private void hasScanGun() {
//        Configuration cfg = getResources().getConfiguration();
//        return cfg.keyboard != Configuration.KEYBOARD_NOKEYS;
//    }
 
//    /**
//     * 掃描槍是否連接
//     * @return
//     */
//    public boolean hasScanGun() {
//
//        if (mBluetoothAdapter == null) {
//            return false;
//        }
//
//        Set<BluetoothDevice> blueDevices = mBluetoothAdapter.getBondedDevices();
//
//        if (blueDevices == null || blueDevices.size() <= 0) {
//            return false;
//        }
//
//        for (Iterator<BluetoothDevice> iterator = blueDevices.iterator(); iterator.hasNext(); ) {
//            BluetoothDevice bluetoothDevice = iterator.next();
//
//            if (bluetoothDevice.getBluetoothClass().getMajorDeviceClass() == BluetoothClass.Device.Major.PERIPHERAL) {
//                mDeviceName = bluetoothDevice.getName();
//                return isInputDeviceExist(mDeviceName);
//            }
//
//        }
//
//        return false;
//
//    }
 
    /**
     * 輸入設備是否存在
     * @param deviceName
     * @return
     */
    private boolean isInputDeviceExist(String deviceName) {
        int[] deviceIds = InputDevice.getDeviceIds();
 
        for (int id : deviceIds) {
            if (InputDevice.getDevice(id).getName().equals(deviceName)) {
                return true;
            }
        }
        return false;
    }
 
    /**
     * 是否為掃碼槍事件(部分機型KeyEvent獲取的名字錯誤)
     * @param event
     * @return
     */
    @Deprecated
    public boolean isScanGunEvent(KeyEvent event) {
        return event.getDevice().getName().equals(mDeviceName);
    }
 
}

 //實現(xiàn)上述類接口‘
public class MainActivity extends AppCompatActivity implements
        ScanGunKeyEventHelper.OnScanSuccessListener
//重寫掃碼槍識別返回數(shù)據(jù)
@Override
       public void onScanSuccess(String barcode) {
 
        barCode = barcode;
        if (barcode != null && recordPrice > 0 && payString.equals
                ("readyPay")) {
            payDishs();
        }
    }
 
//重寫捕捉到掃碼槍事件
    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
 
    mScanGunKeyEventHelper.analysisKeyEvent(event);
        return true;
    }