请教各位大神为什么OnDeviceChange总是收到7？

xhlu 2020-01-03 06:23:36

请教各位大神为什么OnDeviceChange总是收到7？设备已注册，也没有提示注册失败，为什么只能收到7？

 //注册部分

       UID guid;

       HRESULT hr = CoCreateGuid(&guid);

   

	//在对话框初始化过程中将设备通知消息注册到winproc中

	//Register to receive notification when a USB device is plugged in.

	HDEVNOTIFY gNotifyDevHandle;

	DEV_BROADCAST_DEVICEINTERFACE broadcastInterface;

	broadcastInterface.dbcc_size =sizeof(DEV_BROADCAST_DEVICEINTERFACE);

	broadcastInterface.dbcc_devicetype =DBT_DEVTYP_DEVICEINTERFACE;

	 	

	memcpy( &(broadcastInterface.dbcc_classguid),&(guid),sizeof(struct _GUID));

	

	gNotifyDevHandle = RegisterDeviceNotification(this->GetSafeHwnd(),

	&broadcastInterface,

	DEVICE_NOTIFY_WINDOW_HANDLE);

       //----------------------------------------------------------

        afx_msg BOOL OnDeviceChange(UINT nEventType, DWORD dwData);

       //--------------------------------------------------------------------

        BEGIN_MESSAGE_MAP(CRFIDInputToolDlg, CDialog)

	ON_WM_DEVICECHANGE()

	......

        END_MESSAGE_MAP()

        //--------------------------------------------

          BOOL CRFIDInputToolDlg::OnDeviceChange(UINT nEventType, DWORD dwData)

 {

	DEV_BROADCAST_DEVICEINTERFACE* dbd = (DEV_BROADCAST_DEVICEINTERFACE*) dwData;

	

	switch (nEventType)

    {

    case DBT_DEVICEREMOVECOMPLETE:

        AfxMessageBox(_T("设备移除"));

            break;

    case DBT_DEVICEARRIVAL:

        AfxMessageBox(_T("设备接入"));

            break;

    default:

       break;

     }

}