I am writing an extension for an existing application that needs to handle USB insertion/removal events. I know the VID/PID of the device of interest. However, I don't have access to the window handle, so I don't know if RegisterDeviceNotification will be of much use, unless there is a way to obtain the handle via the WINAPI. What would be the best way to detect USB insertion/removal events with C++?

微软网站上的这个示例代码 显示了如何通过 WMI 接收事件通知:

This sample code on the Microsoft website shows how to receive event notifications via WMI:

如何修改它以接收 USB 插入/移除事件?或者，我还有其他方法可以解决这个问题吗?我使用的是 Visual Studio 2008.谢谢.

How could it be modified to receive USB insertion/removal events? Or, is there another way I should be going about this? I am using Visual Studio 2008. Thanks.

附加信息

这是我目前所拥有的(减去错误处理):

This is what I have so far (minus error-handling):

DEFINE_GUID(GUID_INTERFACE_CP210x, 0x993f7832, 0x6e2d, 0x4a0f, 0xb2, 0x72, 0xe2, 0xc7, 0x8e, 0x74, 0xf9, 0x3e);

MyClass::MyClass()
{
    // Generate message-only window
    _pWndClassEx = (WNDCLASSEX *)malloc( sizeof(WNDCLASSEX) );
    memset( _pWndClassEx, 0, sizeof(WNDCLASSEX) );
    _pWndClassEx->cbSize = sizeof(WNDCLASSEX);
    _pWndClassEx->lpfnWndProc = (WNDPROC)WndProc; // function which will handle messages
    _pWndClassEx->hInstance = GetCurrentModule();
    _pWndClassEx->lpszClassName = pClassName;
    atom = RegisterClassEx( _pWndClassEx );
    _hWnd = CreateWindowEx( 0, pClassName, pWindowName, 0, 0, 0, 0, 0, HWND_MESSAGE, NULL, NULL, NULL );

    // Register the USB device for notification
    _pDevIF = (DEV_BROADCAST_DEVICEINTERFACE *)malloc( sizeof(DEV_BROADCAST_DEVICEINTERFACE) );
    memset( _pDevIF, 0, sizeof(DEV_BROADCAST_DEVICEINTERFACE) );
    _pDevIF->dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE);
    _pDevIF->dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;
    _pDevIF->dbcc_classguid = GUID_INTERFACE_CP210x;
    _hNotifyDevNode = RegisterDeviceNotification( _hWnd, _pDevIF, DEVICE_NOTIFY_WINDOW_HANDLE );
}

static bool OnDeviceChange(UINT nEventType, DWORD dwData)
{
    switch ( nEventType )
    {
    case DBT_DEVICEARRIVAL:
        // A device has been inserted adn is now available.
        break;

    case DBT_DEVICEREMOVECOMPLETE:
        // Device has been removed.
        break;

    default:
        break;
    }

    return true;
}

static LRESULT WndProc( HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam )
{
    switch ( message )
    {
    case WM_DEVICECHANGE:
        OnDeviceChange( wParam, lParam ); // Set breakpoint (never gets here)
        break;

    default:
        break;
    }

    return DefWindowProc(hwnd, message, wParam, lParam);
}

PC 进入 WndProc，但在我移除/插入 USB 设备时不会.PC 似乎从未进入 OnDeviceChange.任何提示将不胜感激.我需要处理 USB 设备的意外插入/移除.如果有所不同，USB 设备将作为 Windows 的虚拟 COM 端口出现.谢谢.

The PC gets into WndProc, but not when I remove/insert my USB device. The PC never seems to get into OnDeviceChange. Any tips would be appreciated. I need to handle unexpected insertions/removals of the USB device. If it makes a difference, the USB device appears as a virtual COM port to Windows. Thanks.

附加信息: 使用 RegisterClassEx 返回的类 atom 调用 CreateWindowEx 失败并显示错误消息，找不到窗口类."

Aditional info: Calling CreateWindowEx using the class atom returned by RegisterClassEx fails with the error message, "Cannot find window class."

_hWnd = CreateWindowEx( 0, (LPCTSTR)&atom, pWindowName, 0, 0, 0, 0, 0, HWND_MESSAGE, NULL, NULL, NULL );

新方法

我也在尝试这种新方法.我正在尝试编写一个仅消息窗口来接收 USB 设备的设备更改通知消息.我正在使用 MFC、C++ 和 Visual Studio 2008.一切都可以编译，并且它在运行时不会崩溃或锁定，但从未触发事件处理程序.感兴趣的设备作为虚拟 COM 端口安装在 Windows 上.

I'm also trying this new approach. I'm trying to get write a message-only window to receive device change notification messages for a USB device. I am using MFC, C++, and Visual Studio 2008. Everything compiles, and it runs without crashing or locking up, but the event handler is never triggered. The device of interest is installed on Windows as a virtual COM port.

我的主应用程序实例化下面描述的类，然后使用 while 循环等待来自键盘轮询的字符输入.正是在这段等待时间内，我移除并插入了我的 USB 设备，期待事件被触发.

My main application instantiates the class described below then waits for a character input from the keyboard polling using a while loop. It is during this wait time that I remove and insert my USB device expecting the event to get fired.

class CMessageOnlyWindow : public CWnd
{
    DECLARE_DYNAMIC(CMessageOnlyWindow)
private:
    DEV_BROADCAST_DEVICEINTERFACE * _pDevIF; // The notification filter.
    HDEVNOTIFY _hNotifyDev;             // The device notification handle.
public:
    CMessageOnlyWindow();
    virtual ~CMessageOnlyWindow();
protected:
    afx_msg BOOL OnDeviceChange( UINT nEventType, DWORD dwData );
private:
    void RegisterNotification( void );
    void UnregisterNotification( void );
protected:
    DECLARE_MESSAGE_MAP()               // Must be last.
};

为简单起见，我删除了所有清理和错误处理:

For simplicity, I've removed all the cleanup and error-handling:

DEFINE_GUID(GUID_INTERFACE_CP210x, 0x993f7832, 0x6e2d, 0x4a0f, 
    0xb2, 0x72, 0xe2, 0xc7, 0x8e, 0x74, 0xf9, 0x3e);

IMPLEMENT_DYNAMIC(CMessageOnlyWindow, CWnd)

CMessageOnlyWindow::CMessageOnlyWindow()
{
    CString cstrWndClassName = ::AfxRegisterWndClass( NULL );
    BOOL bCreated = this->CreateEx( 0, cstrWndClassName,
        L"CMessageOnlyWindow", 0, 0, 0, 0, 0, HWND_MESSAGE, 0 );
    this->RegisterNotification();
}

CMessageOnlyWindow::~CMessageOnlyWindow() {}

BEGIN_MESSAGE_MAP(CMessageOnlyWindow, CWnd)
    ON_WM_DEVICECHANGE()
END_MESSAGE_MAP()

afx_msg BOOL CMessageOnlyWindow::OnDeviceChange( UINT nEventType, DWORD dwData )
{
    switch ( nEventType ) // <-- Never gets here.
    {
    case DBT_DEVICEARRIVAL:
        break;

    case DBT_DEVICEREMOVECOMPLETE:
        break;

    default:
        break;
    }

    return TRUE;
}

void CMessageOnlyWindow::RegisterNotification(void)
{
    _pDevIF = (DEV_BROADCAST_DEVICEINTERFACE *)malloc( sizeof(DEV_BROADCAST_DEVICEINTERFACE) );
    memset( _pDevIF, 0, sizeof(DEV_BROADCAST_DEVICEINTERFACE) );
    _pDevIF->dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE);
    _pDevIF->dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;
    _pDevIF->dbcc_classguid = GUID_INTERFACE_CP210x;
    _hNotifyDev = RegisterDeviceNotification( this->m_hWnd, _pDevIF, DEVICE_NOTIFY_WINDOW_HANDLE );
}

void CMessageOnlyWindow::UnregisterNotification(void)
{
    UnregisterDeviceNotification( _hNotifyDev );
}

任何想法或建议将不胜感激.如果缺少任何细节，请告诉我，我会很乐意添加它们.谢谢.

Any thoughts or suggestions would be much appreciated. If any details are missing, let me know, and I will be glad to add them. Thanks.

仅消息窗口需要在新线程中启动，还是创建新窗口会自动脱离新线程?

Does the message-only window need to be started in a new thread, or does creating a new window automatically spin off a new thread?

推荐答案

创建一个只等待 WM_DEVICECHANGE 并使用 RegisterDeviceNotification 注册该窗口的虚拟窗口.恕我直言，WMI 在这里有点矫枉过正.

Create a dummy window that does nothing but wait for WM_DEVICECHANGE and register that window using RegisterDeviceNotification. WMI is an overkill here, IMHO.

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