[英]getting drive name from usb device
我有一个wpf applicatin,它将检测USB棒的添加和删除,并给我驱动器名称。 目前,我有这个:
protected override void OnSourceInitialized(EventArgs e)
{
base.OnSourceInitialized(e);
// Adds the windows message processing hook and registers USB device add/removal notification.
HwndSource source = HwndSource.FromHwnd(new WindowInteropHelper(this).Handle);
if (source != null)
{
IntPtr windowHandle = source.Handle;
source.AddHook(HwndHandler);
UsbNotification.RegisterUsbDeviceNotification(windowHandle);
}
}
// Convert to the Drive name (”D:”, “F:”, etc)
private string ToDriveName(int mask)
{
char letter;
string drives = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
// 1 = A
// 2 = B
// 4 = C...
int cnt = 0;
int pom = mask / 2;
while (pom != 0)
{
// while there is any bit set in the mask
// shift it to the righ...
pom = pom / 2;
cnt++;
}
if (cnt < drives.Length)
letter = drives[cnt];
else
letter = '?';
string strReturn;
strReturn= letter + ":\\";
return strReturn;
}
/// <summary>
/// Method that receives window messages.
/// </summary>
private IntPtr HwndHandler(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam, ref bool handled)
{
if (msg == UsbNotification.WmDevicechange)
{
switch ((int)wparam)
{
case UsbNotification.DbtDeviceremovecomplete:
Usb_DeviceRemoved(); // this is where you do your magic
break;
case UsbNotification.DbtDevicearrival:
DEV_BROADCAST_VOLUME volume = (DEV_BROADCAST_VOLUME)Marshal.PtrToStructure(lparam, typeof(DEV_BROADCAST_VOLUME));
Usb_DeviceAdded(ToDriveName(volume.dbcv_unitmask)); // this is where you do your magic
break;
}
}
handled = false;
return IntPtr.Zero;
}
// Contains information about a logical volume.
[StructLayout(LayoutKind.Sequential)]
private struct DEV_BROADCAST_VOLUME
{
public int dbcv_size;
public int dbcv_devicetype;
public int dbcv_reserved;
public int dbcv_unitmask;
}
private void Usb_DeviceRemoved()
{
//todo something
}
private void Usb_DeviceAdded(string strDrive)
{
//todo something
}
到目前为止,这可以正常工作,至少可以检测到USB插入和移除。
但是插入棒后,我需要知道驱动器名称,以便可以将文件复制到USB棒上。
不幸的是,ToDriveName返回并显示“?” 作为驱动器号。
我也试过这个:
private string ToDriveName(int Mask)
{
int i = 0;
for (i = 0; i < 26; ++i)
{
if ((Mask & 0x1) == 0x1) break;
Mask = Mask >> 1;
}
char cLetter= (char)(Convert.ToChar(i) + 'A');
string strReturn;
strReturn= cLetter + ":\\";
return strReturn;
}
然后我得到一个E:\\而不是G:\\ G:是我的USB记忆棒,E是我的DVD驱动器
在调试器中,我的卷中包含以下值:dbch_Size 0x000000d2
dbch_Devicetype 0x00000005
dbch_Unitmask 0xa5dcbf10
dbch_Reserved 0x00000000
铸造到DEV_BROADCAST_VOLUME
时候才有意义dbch_Devicetype
是DBT_DEVTYP_VOLUME
(2)。
你需要
if (volume.dbch_Devicetype == 2) Usb_DeviceAdded(ToDriveName(volume.dbcv_unitmask));
严格来说,您应该首先使用DEV_BROADCAST_HDR
测试设备类型,并且只有在设备类型为2时才使用DEV_BROADCAST_VOLUME
。
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