我需要与 Android 上的 HID 设备进行交互。问题是我使用的是 Qt Android，而我没有使用 Java UsbManager 类。
是否有任何 C 库可供我链接，以便与 Android 上的 HID 设备进行通信，而无需使用 Java API？
我找到了这个：
http://source.android.com/devices/reference/bt__hh_8h_source.html
这似乎是定义 HID 通信的标头，但我找不到关联的库。有什么想法吗？
提前致谢
【问题讨论】：
标签： android qt android-ndk usb hid
我找到了一种方法。就我而言，我正在为设备开发一个控制面板，我需要它在没有设备根的情况下在每台设备上工作。
基本上我使用 UsbManager 来查找和抓取设备。然后我打开设备并从 UsbDeviceConnection 调用 getFileDescriptor() 方法。然后我将此 int 传递给本机代码端。从那里我可以使用任何类型的请求轻松地从设备获取数据，而无需将数据从本机代码传递到 java，反之亦然，通过 JNI，这是缓慢而缓慢的工作。
最棘手的部分实际上是执行需要具有特殊格式的 ioctl 调用。
这些代码的一部分已经在 libusb 源代码中得到了很好的例证，因为这是他们实现对 linux 内核的 libsub 调用的方式。
如果有人知道这个问题的更好解决方案，请告诉我。
带有 USBManager 挂钩的 Android 活动代码：
public class MyActivity extends QtActivity
{
private static MyActivity m_instance;
private UsbAccessory accessory;
private String TAG = "TAG";
private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
private PendingIntent mPermissionIntent;
private UsbManager manager;
private UsbDeviceConnection connection;
private HashMap<Integer, Integer> connectedDevices;
public MyActivity()
{
m_instance = this;
connectedDevices = new HashMap<Integer, Integer>();
}
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
manager = (UsbManager) getSystemService(Context.USB_SERVICE);
registerReceiver(usbManagerBroadcastReceiver, new IntentFilter(UsbManager.ACTION_USB_DEVICE_ATTACHED));
registerReceiver(usbManagerBroadcastReceiver, new IntentFilter(UsbManager.ACTION_USB_DEVICE_DETACHED));
registerReceiver(usbManagerBroadcastReceiver, new IntentFilter(ACTION_USB_PERMISSION));
mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
final Handler handler = new Handler();
handler.postDelayed(new Runnable()
{
@Override
public void run()
{
checkForDevices();
}
}, 1000);
}
@Override
public void onDestroy()
{
super.onDestroy();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
super.onActivityResult(requestCode, resultCode, data);
}
private static native void notifyDeviceAttached(int fd);
private static native void notifyDeviceDetached(int fd);
private final BroadcastReceiver usbManagerBroadcastReceiver = new BroadcastReceiver()
{
public void onReceive(Context context, Intent intent)
{
try
{
String action = intent.getAction();
Log.d(TAG, "INTENT ACTION: " + action);
if (ACTION_USB_PERMISSION.equals(action))
{
Log.d(TAG, "onUsbPermission");
synchronized (this)
{
UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false))
{
if(device != null)
{
int fd = connectToDevice(device);
Log.d(TAG,"device file descriptor: " + fd);
notifyDeviceAttached(fd);
}
}
else
{
Log.d(TAG, "permission denied for device " + device);
}
}
}
if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action))
{
Log.d(TAG, "onDeviceConnected");
synchronized(this)
{
UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (device != null)
{
manager.requestPermission(device, mPermissionIntent);
}
}
}
if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action))
{
Log.d(TAG, "onDeviceDisconnected");
synchronized(this)
{
UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
int fd = connectedDevices.get(device.getDeviceId());
Log.d(TAG, "device: " + device.getDeviceId() + " disconnected. fd: " + fd);
notifyDeviceDetached(fd);
connectedDevices.remove(device.getDeviceId());
}
}
}
catch(Exception e)
{
Log.d(TAG, "Exception: " + e);
}
}
};
private int connectToDevice(UsbDevice device)
{
connection = manager.openDevice(device);
// if we make this, kernel driver will be disconnected
connection.claimInterface(device.getInterface(0), true);
Log.d(TAG, "inserting device with id: " + device.getDeviceId() + " and file descriptor: " + connection.getFileDescriptor());
connectedDevices.put(device.getDeviceId(), connection.getFileDescriptor());
return connection.getFileDescriptor();
}
private void checkForDevices()
{
HashMap<String, UsbDevice> deviceList = manager.getDeviceList();
Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
while(deviceIterator.hasNext())
{
UsbDevice device = deviceIterator.next();
if (device.getVendorId()==VID && device.getProductId()==PID)
{
Log.d(TAG, "Found a device: " + device);
manager.requestPermission(device, mPermissionIntent);
}
}
}
}
当具有希望的 VID 和 PID 的设备连接或断开连接时，本机调用 notifyDeviceAttached(int fd) 和 notifyDeviceDetached(int fd) 被调用，将设备的文件描述符发送到本机端。在我的例子中，我实例化了一个设备类型的类。此时设备已经打开，您可以开始对其进行调用。在 Linux 中，您可以像 libusb 一样进行 ioctl 调用。您可以查看下面的 getFeature 和 setFeature 代码。如果您需要除此之外的任何其他内容，可以查看 libusb 源代码。
C++ 原生端代码：
#include <sys/ioctl.h>
#include <unistd.h>
#include <errno.h>
#include <QDebug>
#include <QElapsedTimer>
static inline uint16_t cpu_to_le16(const uint16_t x)
{
union
{
uint8_t b8[2];
uint16_t b16;
} _tmp;
_tmp.b8[1] = (uint8_t) (x >> 8);
_tmp.b8[0] = (uint8_t) (x & 0xff);
return _tmp.b16;
}
struct usbdevfs_ctrltransfer
{
unsigned char bRequestType;
unsigned char bRequest;
unsigned short wValue;
unsigned short wIndex;
unsigned short wLength;
unsigned int timeout;
void *data;
};
Device::Device(int fileDescriptor, QObject *parent) :
fd(fileDescriptor)
{
}
int Device::getFeature(unsigned char reportId, unsigned char *buffer, int length)
{
struct usbdevfs_ctrltransfer data;
data.bRequestType = (0x01 << 5)|0x01|0x80;
data.bRequest = 0x01;
data.wValue = cpu_to_le16((3 << 8) | reportId);
data.wIndex = cpu_to_le16(0);
data.wLength = cpu_to_le16(length);
data.data = buffer;
data.timeout = 1000;
int res = ioctl(fd, _IOWR('U', 0, struct usbdevfs_ctrltransfer), &data);
if (res<0)
{
qDebug() << "error: " << strerror(errno);
}
return res;
}
int Device::setFeature(unsigned char reportId, unsigned char *buffer, int length)
{
struct usbdevfs_ctrltransfer data;
data.bRequestType = (0x01 << 5)|0x01|0x00;
data.bRequest = 0x09;
data.wValue = cpu_to_le16((3 << 8) | reportId);
data.wIndex = cpu_to_le16(0);
data.wLength = cpu_to_le16(length);
data.data = buffer;
data.timeout = 1000;
int res = ioctl(fd, _IOWR('U', 0, struct usbdevfs_ctrltransfer), &data);
if (res<0)
{
qDebug() << "error: " << strerror(errno);
}
return res;
}
问候，
努诺桑托斯
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