1.使用者需要擷取usb 裝置名,來判斷是不是我方的列印機
2.代碼
public String getProductName(){
byte[] rawDescs = mUsbDeviceConnection.getRawDescriptors();
String manufacturer = "", product = "";
try
{
byte[] buffer = new byte[255];
int idxMan = rawDescs[14];
int idxPrd = rawDescs[15];
Logger.i("index",idxMan);
int rdo = mUsbDeviceConnection.controlTransfer(UsbConstants.USB_DIR_IN
| UsbConstants.USB_TYPE_STANDARD, STD_USB_REQUEST_GET_DESCRIPTOR,
(LIBUSB_DT_STRING << 8) | idxMan, 0, buffer, 0xFF, 0);
manufacturer = new String(buffer, 2, rdo - 2, "UTF-16LE");
rdo = mUsbDeviceConnection.controlTransfer(UsbConstants.USB_DIR_IN
| UsbConstants.USB_TYPE_STANDARD, STD_USB_REQUEST_GET_DESCRIPTOR,
(LIBUSB_DT_STRING << 8) | idxPrd, 0, buffer, 0xFF, 0);
product = new String(buffer, 2, rdo - 2, "UTF-16LE");
} catch (Exception e)
{
e.printStackTrace();
Logger.e(e.getMessage());
}
Logger.i("","Manufacturer:" + manufacturer + "\n");
Logger.i("","Product:" + product + "\n");
Logger.i("","Serial#:" + mUsbDeviceConnection.getSerial() + "\n");
return product.trim()+manufacturer.trim();
}
3.參數含義
第一 參數常用的就是向裝置寫資料:0xxxxxxx,向裝置讀資料1xxxxxxx.第二是操作哪個結構資料,第三和第四請求不同有不同含義,
第五 資料存放,第六要讀或者寫的資料長度..
https://blog.csdn.net/obanaganastar/article/details/72866260
4.跟蹤這個方法時 跟到這裡就斷了 是以上面3這個參數我是猜的
int usb_device_control_transfer(struct usb_device *device,
575 int requestType,
576 int request,
577 int value,
578 int index,
579 void* buffer,
580 int length,
581 unsigned int timeout)
582{
583 struct usbdevfs_ctrltransfer ctrl;
584
585 // this usually requires read/write permission
586 if (!usb_device_reopen_writeable(device))
587 return -1;
588
589 memset(&ctrl, 0, sizeof(ctrl));
590 ctrl.bRequestType = requestType;
591 ctrl.bRequest = request;
592 ctrl.wValue = value;
593 ctrl.wIndex = index;
594 ctrl.wLength = length;
595 ctrl.data = buffer;
596 ctrl.timeout = timeout;
597 return ioctl(device->fd, USBDEVFS_CONTROL, &ctrl);
598}
然後調用核心方法
#define USBDEVFS_CONTROL _IOWR('U', 0, struct usbdevfs_ctrltransfer)
5.結果
ps:因為列印機底層的軟體大多是參考愛普生寫,所用可以product 相同 需要用三個拼接在一起比較 .19版本以上才能用UsbDevice 擷取這些資訊. 如果想了解更全可以去下載下傳usb 開發大全 看第四章和第五章.