USB熱插拔檢測：
方法一：
啟動定時器，定時輪詢登錄檔，這種方法容易宕機。
方法二：
註冊視窗，新增Windows訊息 ON_WM_DEVICECHANGE()對映。
步驟：
一： 要想新增訊息對映，需改變三個地方：
1、 視窗標頭檔案宣告訊息處理函式
afx_msg BOOL OnDeviceChange(UINT nEventType, DWORD dwData)
2、 原始檔新增訊息處理函式

BOOL CDownLoadDlg::OnDeviceChange(UINT nEventType,DWORD dwData)
{
    // TODO: 在此新增額外的初始化程式碼
｝ 
3、 原始檔新增訊息

BEGIN_MESSAGE_MAP(CDownLoadDlg, CDialog)
‘’‘’‘’‘’‘’
 ON_WM_DEVICECHANGE()//USB訊息
END_MESSAGE_MAP()
二：訊息處理函式的OnDeviceChange 
 MSDN說明：
The framework calls this member function to notify an application or device driver of a change to the hardware configuration of a device or the computer.
afx_msg BOOL OnDeviceChange(  UINT nEventType, 
                                                        DWORD_PTR dwData  
);

Parameters

nEventType

An event type. See the Remarks section for a description of the available values

dwData

The address of a structure that contains event-specific data. Its meaning depends on the given event.

For devices that offer software-controllable features, such as ejection and locking, the operating system typically sends a DBT_DEVICEREMOVEPENDING 

message to let applications and device drivers end their use of the device gracefully.

If the operating system forcefully removes of a device, it may not send a DBT_DEVICEQUERYREMOVE message before doing so.

The nEvent parameter can be one of these values:

• DBT_DEVICEARRIVAL   A device has been inserted and is now available.

• DBT_DEVICEQUERYREMOVE   Permission to remove a device is requested. Any application can deny this request and cancel the removal.

• DBT_DEVICEREMOVEPENDING   Device is about to be removed. Cannot be denied.

• DBT_CONFIGCHANGED   Current configuration has changed.

• DBT_DEVNODES_CHANGED   Device node has changed.

//DBT_DEVICEARRIVAL                              裝置已插入,現在可用 // //DBT_DEVICEQUERYREMOVE                  允許刪除裝置請求。任何應用程式都可以拒絕這個請求,取消刪除。 // //DBT_DEVICEQUERYREMOVEFAILED      請求刪除一個裝置已經被取消。 // //DBT_DEVICEREMOVEPENDING              裝置將被刪除。不能否認。 // //DBT_DEVICEREMOVECOMPLETE          裝置已被刪除。           // //DBT_DEVICETYPESPECIFIC                   特定於裝置的事件 // //DBT_CONFIGCHANGED                          當前配置發生了變化。 // //DBT_DEVNODES_CHANGED                  裝置節點已經改變了

例子：

BOOL CDownLoadDlg::OnDeviceChange(UINT nEventType,DWORD dwData)
{
//DEV_BROADCAST_DEVICEINTERFACE* dbd = (DEV_BROADCAST_DEVICEINTERFACE*) dwData;//這裡進行資訊匹配,比如guid等
PDEV_BROADCAST_HDRdbd =(PDEV_BROADCAST_HDR)dwData;


//針對各個事件進行處理.
m_StrResult.Empty();
switch (nEventType)
{
case DBT_DEVICEREMOVECOMPLETE:
if(dbd->dbch_devicetype==DBT_DEVTYP_DEVICEINTERFACE)
{
DEV_BROADCAST_DEVICEINTERFACE  *get_dbd;
get_dbd=(DEV_BROADCAST_DEVICEINTERFACE*) dwData;
//名字對比
unsigned shortlength,VID,PID,i;
unsigned char numb[8];
CString get_hid_name;
get_hid_name.Format(_T("%s"),get_dbd->dbcc_name);
length=get_hid_name.GetLength();
if(length<10)
{
return false;
}


for(i=0;i<length-3;i++)
{
if(('H'==get_hid_name.GetAt(i)) && ('I'==get_hid_name.GetAt(i+1)) && ('D'==get_hid_name.GetAt(i+2)))
break;
}
if(i==(length-3))
{
return false;
}
length=i;
for(i=0;i<4;i++)
{
if((get_hid_name.GetAt(i+8+length)<=0x39) && (get_hid_name.GetAt(i+8+length)>=0x30))
{
numb[i]=get_hid_name.GetAt(i+8+length);
numb[i]=numb[i]-0x30;
}
if((get_hid_name.GetAt(i+8+length)<=0x5A) && (get_hid_name.GetAt(i+8+length)>=0x41))
{
numb[i]=get_hid_name.GetAt(i+8+length);
numb[i]=numb[i]-0x37;
}
if((get_hid_name.GetAt(i+8+length)<=0x7A) && (get_hid_name.GetAt(i+8+length)>=0x61))
{
numb[i]=get_hid_name.GetAt(i+8+length);
numb[i]=numb[i]-0x57;
}


if((get_hid_name.GetAt(i+17+length)<=0x39) && (get_hid_name.GetAt(i+17+length)>=0x30))
{
numb[i+4]=get_hid_name.GetAt(i+17+length);
numb[i+4]=numb[i+4]-0x30;
}
if((get_hid_name.GetAt(i+17+length)<=0x5A) && (get_hid_name.GetAt(i+17+length)>=0x41))
{
numb[i+4]=get_hid_name.GetAt(i+17+length);
numb[i+4]=numb[i+4]-0x37;
}
if((get_hid_name.GetAt(i+17)<=0x7A+length) && (get_hid_name.GetAt(i+17+length)>=0x61))
{
numb[i+4]=get_hid_name.GetAt(i+17+length);
numb[i+4]=numb[i+4]-0x57;
}
}
VID=numb[0];
VID=VID<<4;
VID=VID & 0x00F0;
VID=VID |(numb[1] & 0x000F);
VID=VID<<4;
VID=VID & 0x0FF0;
VID=VID |(numb[2] & 0x000F);
VID=VID<<4;
VID=VID & 0xFFF0;
VID=VID |(numb[3] & 0x000F);


PID=numb[4];
PID=PID<<4;
PID=PID & 0x00F0;
PID=PID |(numb[5] & 0x000F);
PID=PID<<4;
PID=PID & 0x0FF0;
PID=PID |(numb[6] & 0x000F);
PID=PID<<4;
PID=PID & 0xFFF0;
PID=PID |(numb[7] & 0x000F);


if((VID==USB_VID) && (PID==USB_PID))
{
CloseUSB();
EditWrite(_T("下載器已移除\r\n"),_T("未連線"));
}
}
else
{
return false;
}
break;
case DBT_DEVICEARRIVAL:
if(hidHandle == INVALID_HANDLE_VALUE)
{
HIDFindFunc();
}
break;


default:
return false;
break;
}
return TRUE;
}

二、設備註冊
如果想獲得正確的 nEventType 值，必須先在視窗初始化函式OnInitDialog()裡面進行註冊，否則值都是7，切要在函式最後（DoModal()函式之後）呼叫。註冊函式用RegisterDeviceNotification()。
MSDN說明：

Registers the device or type of device for which a window will receive notifications.

Syntax

C++ HDEVNOTIFY WINAPI RegisterDeviceNotification( _In_  HANDLE hRecipient, _In_  LPVOID NotificationFilter, _In_  DWORD Flags);

Parameters

hRecipient [in]

A handle to the window or service that will receive device events for the devices specified in the NotificationFilter parameter. The same window handle can be used in multiple calls to RegisterDeviceNotification.

Services can specify either a window handle or service status handle.

NotificationFilter [in]

A pointer to a block of data that specifies the type of device for which notifications should be sent. This block always begins with the DEV_BROADCAST_HDR structure. The data following this header is dependent on the value of the dbch_devicetype member, which can be DBT_DEVTYP_DEVICEINTERFACE or DBT_DEVTYP_HANDLE. For more information, see Remarks.

Flags [in]

This parameter can be one of the following values.

Value	Meaning
DEVICE_NOTIFY_WINDOW_HANDLE 0x00000000	The hRecipient parameter is a  window handle.
DEVICE_NOTIFY_SERVICE_HANDLE 0x00000001	The hRecipient parameter is a service status handle.

In addition, you can specify the following value.

Value	Meaning
DEVICE_NOTIFY_ALL_INTERFACE_CLASSES 0x00000004	Notifies the recipient of device interface events for all device interface  classes. (The dbcc_classguid member is ignored.) This value can be used only if the  dbch_devicetype member is  DBT_DEVTYP_DEVICEINTERFACE.

Return value

If the function succeeds, the return value is a device notification handle.

If the function fails, the return value is NULL. To get extended error information, call GetLastError.

Remarks

Applications send event notifications using the BroadcastSystemMessage function. Any application with a top-level window can receive basic notifications by processing the WM_DEVICECHANGE message. Applications can use theRegisterDeviceNotification function to register to receive device notifications.

Services can use the RegisterDeviceNotification function to register to receive device notifications. If a service specifies a window handle in the hRecipient parameter, the notifications are sent to the window procedure. IfhRecipient is a service status handle, SERVICE_CONTROL_DEVICEEVENT notifications are sent to the service control handler. For more information about the service control handler, see HandlerEx.

Be sure to handle Plug and Play device events as quickly as possible. Otherwise, the system may become unresponsive. If your event handler is to perform an operation that may block execution (such as I/O), it is best to start another thread to perform the operation asynchronously.

Device notification handles returned by RegisterDeviceNotification must be closed by calling the UnregisterDeviceNotification function when they are no longer needed.

The DBT_DEVICEARRIVAL and DBT_DEVICEREMOVECOMPLETE events are automatically broadcast to all top-level windows for port devices. Therefore, it is not necessary to call RegisterDeviceNotification for ports, and the function fails if the dbch_devicetype member is DBT_DEVTYP_PORT. Volume notifications are also broadcast to top-level windows, so the function fails if dbch_devicetype is DBT_DEVTYP_VOLUME. OEM-defined devices are not used directly by the system, so the function fails if dbch_devicetype is DBT_DEVTYP_OEM.

例子：
bool CDownLoadDlg::RegisterHidDeviceNotify(void) {     GUID HidGuid;                                       /* temporarily stores Windows HID Class GUID */       DEV_BROADCAST_DEVICEINTERFACE NotificationFilter;   /* un/plug notification filter */   HDEVNOTIFY m_hDevNotify;     /* Set up device notification (i.e. plug or unplug of HID Devices) */       /* 1) get the HID GUID */       HidD_GetHidGuid(&HidGuid);       /* 2) clear the notification filter */       ZeroMemory( &NotificationFilter, sizeof(NotificationFilter));       /* 3) assign the previously cleared structure with the correct data      so that the application is notified of HID device un/plug events */       NotificationFilter.dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE);       NotificationFilter.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;       NotificationFilter.dbcc_classguid  = HidGuid;       /* 4) register device notifications for this application */       m_hDevNotify = RegisterDeviceNotification(  this->GetSafeHwnd(),//AfxGetMainWnd()->m_hWnd,                                                   &NotificationFilter,                                                    DEVICE_NOTIFY_WINDOW_HANDLE);       /* 5) notify the calling procedure if the HID device will not be recognized */       if(!m_hDevNotify) {         return FALSE; } else { return TRUE;   } }