我正在使用以下代码通过连接到我的三星打印机的 USB 数据线通过 android 设备进行打印。

当使用 startPrinting 方法时，它在调试日志中给出了以下验证:

1. 打印机命令发送成功
2. 已获得打印机许可。

打印机甚至开始发出哔哔声，但我提供的数据没有打印出来。我被困在这个阶段，也没有找到谷歌或 stackoverflow 的帮助。

注意:没有崩溃也没有报错

我正在 Android Jelly bean 4.3 操作系统上测试这段代码

如有任何帮助，我们将不胜感激。

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;

int protocol;

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

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

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

        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";

                protocol = usbDevice1.getDeviceProtocol();

                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();
            }

        print.setOnClickListener(new View.OnClickListener()
            {
                @Override
                public void onClick(View view)
                    {
                        mPermissionIntent = PendingIntent.getBroadcast(MainActivity.this, 0, new Intent(ACTION_USB_PERMISSION), 0);
                        IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
                        registerReceiver(mUsbReceiver, filter);
                        if (mDevice != null)
                            mUsbManager.requestPermission(mDevice, mPermissionIntent);
                        // else
                        // Toast.makeText(this, "USB ", Toast.LENGTH_SHORT).show();

                        // 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);

                                                Log.i("Info", "Device permission granted");
                                                startPrinting(device);

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

public void startPrinting(final UsbDevice printerDevice)
    {
        Handler handler = new Handler();
        handler.post(new Runnable()
            {
                UsbDeviceConnection conn;
                UsbInterface usbInterface;

                @Override
                public void run()
                    {
                        try
                            {
                                Log.i("Info", "Bulk transfer started");
                                // usbInterface = printerDevice.getInterface(0);

                                for (int i = 0; i < printerDevice.getInterfaceCount(); i++)
                                    {
                                        usbInterface = printerDevice.getInterface(i);

                                        if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_PRINTER)
                                            {
                                                // usbInterface = mDevice;
                                            }
                                    }

                                UsbEndpoint endPoint = usbInterface.getEndpoint(0);
                                conn = mUsbManager.openDevice(mDevice);
                                conn.claimInterface(usbInterface, true);

                                String myStringData = "TEXT";
                                myStringData += "\n";
                                byte[] array = myStringData.getBytes();
                                ByteBuffer output_buffer = ByteBuffer.allocate(array.length);
                                UsbRequest request = new UsbRequest();
                                request.initialize(conn, endPoint);
                                request.queue(output_buffer, array.length);
                                if (conn.requestWait() == request)
                                    {
                                        Log.i("Info", output_buffer.getChar(0) + "");
                                        Message m = new Message();
                                        m.obj = output_buffer.array();
                                        output_buffer.clear();
                                    }
                                else
                                    {
                                        Log.i("Info", "No request recieved");
                                    }
                                int transfered = conn.bulkTransfer(endPoint, myStringData.getBytes(), myStringData.getBytes().length, 5000);
                                Log.i("Info", "Amount of data transferred : " + transfered);

                            }
                        catch (Exception e)
                            {
                                Log.e("Exception", "Unable to transfer bulk data");
                                e.printStackTrace();
                            }
                        finally
                            {
                                try
                                    {
                                        conn.releaseInterface(usbInterface);
                                        Log.i("Info", "Interface released");
                                        conn.close();
                                        Log.i("Info", "Usb connection closed");
                                        unregisterReceiver(mUsbReceiver);
                                        Log.i("Info", "Brodcast reciever unregistered");
                                    }
                                catch (Exception e)
                                    {
                                        Log.e("Exception", "Unable to release resources because : " + e.getMessage());
                                        e.printStackTrace();
                                    }
                            }

                    }
            });
    }

private void print(UsbDeviceConnection connection, UsbInterface intrface)
    {
        String test = "THIS IS A PRINT TEST";
        // String text = "#move " + protocol + ";" + "#print" + test;
        // Log.e("text", text);
        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);

        connection.close();
    }

最佳答案

当打印机制造商在 USB 总线上使用专有(且未公开 :-( ) 协议(protocol)时，我在其他操作系统中遇到过这种确切的行为。具体来说，我想到了 HP Laserjet P1060 系列。两者都使用 GNU/Linux 和 Mac OS-X，操作系统可以很好地发现打印机，并尝试使用通用驱动程序(例如 HP Laserjet II)进行打印。打印机的 LED 开始闪烁 - 但什么也没有出来。这感觉有点像一些命令缺少使打印机实际打印页面的功能。

在这些情况下，需要下载专有固件 blob 才能正常运行。不幸的是，可能很难找到适用于家庭/小型企业打印机型号的 Android 驱动程序。我在三星移动打印应用程序 ( http://www.samsung.com/us/mobile-print-app/ ) 和 departamental 网络激光打印机 (ML 3471-ND 等) 方面运气不错。这是通过 Wifi + 以太网实现的。

HTH.

关于java - 使用 USB 电缆打印问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30507749/