批量传输和 Android USB API

我有一个程序，我尝试通过 USB 将我的 Android 设备连接到网络摄像头。我在一些事情上遇到了麻烦，即正确传输数据。我尝试过使用bulkTransfer，但似乎无法识别它的使用情况。我一直在尝试寻找可能对我有帮助的例子，例如here https://stackoverflow.com/questions/13982264/usb-bulktransfer-between-android-tablet-and-camera但没有人能帮助我 - 他们的结构似乎比我的更好，但每当我切换时，我的程序就会在加载时崩溃。

我相当有信心我的字节声明也是不正确的，我应该以某种方式将我的数据转发到那里，但我不确定如何。任何有关如何数据传输和如何构建我的代码方面的帮助将不胜感激。

一些声明：

private byte[] bytes = {1,2};
private static int TIMEOUT = 0;
private boolean forceClaim = true;

在创建时：

UsbDevice device = (UsbDevice) getIntent().getParcelableExtra(UsbManager.EXTRA_DEVICE);
    UsbManager mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
    HashMap<String, UsbDevice> deviceList = mUsbManager.getDeviceList();
    Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
    while(deviceIterator.hasNext()) {
        device = deviceIterator.next();
        PendingIntent mPermissionIntent = PendingIntent.getBroadcast(this,0,new Intent(ACTION_USB_PERMISSION), 0);
        IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
        registerReceiver(mUsbReceiver, filter);
        mUsbManager.requestPermission(device, mPermissionIntent);
        UsbDeviceConnection connection = mUsbManager.openDevice(device);
        Log.d("CAM Connection", " " + connection);
        Log.d("CAM UsbManager", " " + mUsbManager);
        Log.d("CAM Device", " " + device);



        UsbInterface intf = device.getInterface(0);
        Log.d("CAM_INTF Interface!!!!", " " +  intf );
        UsbEndpoint endpoint = intf.getEndpoint(0);
        Log.d("CAM_END Endpoint", " " +  endpoint );

        connection.claimInterface(intf, forceClaim);
        StringBuilder sb = new StringBuilder();
        if(connection.bulkTransfer(endpoint,bytes,bytes.length,TIMEOUT) < 2)
            Log.d("test", "");
       //Log.d("BULK", ""+ connection.bulkTransfer(endpoint, bytes, bytes.length, TIMEOUT)); //do in another thread
    }

附加相关代码：

 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(EXTRA_PERMISSION_GRANTED, false)) {
                    if(device != null){



                        //call method to set up device communication
                    }
                }
                else {
                    Log.d("Deny:", "permission denied for device " + device);
                }
            }
        }
    }
};

你的问题之一是寻找端点。 endpoint0 用于控制任务，您应该在代码中找到适当的 IN 和 OUT 端点。

 UsbInterface usbInterfaceTemp = null;
        usbInterface = null;
        endpointIN = null;
        endpointOUT = null;
        for (int i = 0; i < usbGotPermiDVC.getInterfaceCount(); i++) {

            usbInterfaceTemp = usbGotPermiDVC.getInterface(i);
            if (usbInterfaceTemp.getEndpointCount() >= 2) {

                for (int j = 0; j < usbInterfaceTemp.getEndpointCount(); j++) {

                    UsbEndpoint usbEndpointTemp = usbInterfaceTemp.getEndpoint(j);

                    if (usbEndpointTemp.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK) {

                        if (usbEndpointTemp.getDirection() == UsbConstants.USB_DIR_IN) {

                            endpointIN = usbEndpointTemp;

                        } else if (usbEndpointTemp.getDirection() == UsbConstants.USB_DIR_OUT) {

                            endpointOUT = usbEndpointTemp;

                        }
                    }
                }
            }
        }

        if (endpointIN != null && endpointOUT != null) {
            usbInterface = usbInterfaceTemp;
        }

        if (usbInterface == null) {
            return;
        }


        usbDeviceConnection = usbManager.openDevice(usbSelectedDevice);

        if (!(usbDeviceConnection != null && usbDeviceConnection.claimInterface(usbInterface, true))) {
            usbDeviceConnection = null;
            return;
        }

        usbDeviceConnection.controlTransfer(0x21, 34, 0, 0, null, 0, 0);
        usbDeviceConnection.controlTransfer(0x21, 32, 0, 0, new byte[]{(byte) 0x80,
                0x25, 0x00, 0x00, 0x00, 0x00, 0x08}, 7, 0);

        Toast.makeText(getApplicationContext(), "Device opened and Interface claimed!", Toast.LENGTH_SHORT).show();

其中usbGotPermiDVC为获得USB访问权限的设备。