通过USB从Android设备向热敏打印机发送数据

我正在处理从我的应用程序向热敏打印机发送数据 . 我已经让它在网络上正常工作，我的数据打印正确 . 现在有一个额外的要求，我们也必须能够通过USB打印 .

这是我尝试过的：

private UsbManager mUsbManager;
    private UsbDevice mDevice;
    private UsbDeviceConnection mConnection;
    private UsbInterface mInterface;
    private UsbEndpoint mEndPoint;
    private PendingIntent mPermissionIntent;
    private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
    private static Boolean forceCLaim = true;

    HashMap<String, UsbDevice> mDeviceList;
    Iterator<UsbDevice> mDeviceIterator;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);

        mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
        mDeviceList = mUsbManager.getDeviceList();    
        mDeviceIterator = mDeviceList.values().iterator();

        Button print = (Button)findViewById(R.id.print);

        Toast.makeText(this, "Device List Size: " + String.valueOf(mDeviceList.size()), Toast.LENGTH_SHORT).show();
        TextView textView = (TextView) findViewById(R.id.usbDevice);
        String usbDevice = "";
        //This is just testing what devices are connected
        while (mDeviceIterator.hasNext()) {
            UsbDevice usbDevice1 = mDeviceIterator.next();
            usbDevice += "\n" +
                    "DeviceID: " + usbDevice1.getDeviceId() + "\n" +
                    "DeviceName: " + usbDevice1.getDeviceName() + "\n" +
                    "DeviceClass: " + usbDevice1.getDeviceClass() + " - " + translateDeviceClass(usbDevice1.getDeviceClass()) + "\n" +
                    "DeviceSubClass: " + usbDevice1.getDeviceSubclass() + "\n" +
                    "VendorID: " + usbDevice1.getVendorId() + "\n" +
                    "ProductID: " + usbDevice1.getProductId() + "\n";

            int interfaceCount = usbDevice1.getInterfaceCount();
            Toast.makeText(this, "INTERFACE COUNT: " + String.valueOf(interfaceCount), Toast.LENGTH_SHORT).show();

            mDevice = usbDevice1;

            if (mDevice == null) {
                Toast.makeText(this, "mDevice is null", Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(this, "mDevice is not null", Toast.LENGTH_SHORT).show();
            }
            textView.setText(usbDevice);
        }

        if (mDevice == null) {
            Toast.makeText(this, "mDevice is null", Toast.LENGTH_SHORT).show();
        }else{
            Toast.makeText(this, "mDevice is not null", Toast.LENGTH_SHORT).show();
        }

        mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
        IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
        registerReceiver(mUsbReceiver, filter);
        mUsbManager.requestPermission(mDevice, mPermissionIntent);

  print.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //setup();
                print(mConnection, mInterface);
            }
        });
}

   private String translateDeviceClass(int deviceClass){
        switch(deviceClass){
            case UsbConstants.USB_CLASS_APP_SPEC:
                return "Application specific USB class";
            case UsbConstants.USB_CLASS_AUDIO:
                return "USB class for audio devices";
            case UsbConstants.USB_CLASS_CDC_DATA:
                return "USB class for CDC devices (communications device class)";
            case UsbConstants.USB_CLASS_COMM:
                return "USB class for communication devices";
            case UsbConstants.USB_CLASS_CONTENT_SEC:
                return "USB class for content security devices";
            case UsbConstants.USB_CLASS_CSCID:
                return "USB class for content smart card devices";
            case UsbConstants.USB_CLASS_HID:
                return "USB class for human interface devices (for example, mice and keyboards)";
            case UsbConstants.USB_CLASS_HUB:
                return "USB class for USB hubs";
            case UsbConstants.USB_CLASS_MASS_STORAGE:
                return "USB class for mass storage devices";
            case UsbConstants.USB_CLASS_MISC:
                return "USB class for wireless miscellaneous devices";
            case UsbConstants.USB_CLASS_PER_INTERFACE:
                return "USB class indicating that the class is determined on a per-interface basis";
            case UsbConstants.USB_CLASS_PHYSICA:
                return "USB class for physical devices";
            case UsbConstants.USB_CLASS_PRINTER:
                return "USB class for printers";
            case UsbConstants.USB_CLASS_STILL_IMAGE:
                return "USB class for still image devices (digital cameras)";
            case UsbConstants.USB_CLASS_VENDOR_SPEC:
                return "Vendor specific USB class";
            case UsbConstants.USB_CLASS_VIDEO:
                return "USB class for video devices";
            case UsbConstants.USB_CLASS_WIRELESS_CONTROLLER:
                return "USB class for wireless controller devices";
            default: return "Unknown USB class!";
        }
//Broadcast receiver to obtain permission from user for connection
 private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {

        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (ACTION_USB_PERMISSION.equals(action)) {
                synchronized (this) {
                    UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);

                    if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
                        if(device != null){
                            //call method to set up device communication
                            mInterface = device.getInterface(0);
                            mEndPoint = mInterface.getEndpoint(0);
                            mConnection = mUsbManager.openDevice(device);

                            //setup();
                        }
                    }
                    else {
                        //Log.d("SUB", "permission denied for device " + device);
                        Toast.makeText(context, "PERMISSION DENIED FOR THIS DEVICE", Toast.LENGTH_SHORT).show();
                    }
                }
            }
        }
    };

 private void print(UsbDeviceConnection connection, UsbInterface intrface){

        String test = "THIS IS A PRINT TEST";
        byte [] testBytes = test.getBytes();

        if(intrface==null){
            Toast.makeText(this, "INTERFACE IS NULL", Toast.LENGTH_SHORT).show();
        }
        if(connection==null){
            Toast.makeText(this, "CONNECTION IS NULL", Toast.LENGTH_SHORT).show();
        }

        if(forceCLaim==null){
            Toast.makeText(this, "FORCE CLAIM IS NULL", Toast.LENGTH_SHORT).show();
        }   

        connection.claimInterface(intrface, forceCLaim);
        connection.bulkTransfer(mEndPoint, testBytes, testBytes.length, 0);

    }

所以设备连接到usb设备，但是当我尝试批量传输没有任何反应时，有人可以解释这个吗？ Usb连接对我来说是一个新领域，所以任何提示都值得赞赏

EDIT

So it turns out there were issues with endpoints and no returns from the bulktransfer, however, now those issues are resolved and it returns that the bulk transfer is successful, however, it still doesn't print. Does anyone have any ideas on this please??