VCWM_DEVICECHANGE消息，实时捕获U盘插入、移除

 
WM_DEVICECHANGE使用方式有两种，一种是直接在Windows窗口回调函数中使用，另一种便需要自己注册一下，并编写On函数。
 
第一种，在回调函数中添加“case WM_DEVICECHANGE:”，并且可以直接判断wParam，如下。
switch (wParam)
   {
    case DBT_DEVICEARRIVAL:    
    case DBT_DEVICEREMOVECOMPLETE:｝
在其中便可判断了，当然需要自己写相应代码，李木所写程序展示如下，这便是一个最基本的U盘检测程序，能够实时检测U盘的插入、卸载，并获得U盘的盘符，显示出来。
 
1、在Dialog.cpp中新增消息。
BEGIN_MESSAGE_MAP(CDeviceMonitorDlg, CDialog)
ON_WM_PAINT()
ON_WM_QUERYDRAGICON()
//}}AFX_MSG_MAP
ON_WM_DEVICECHANGE()
END_MESSAGE_MAP()
2、新增响应函数。
DECLARE_MESSAGE_MAP()
public:
afx_msg BOOL OnDeviceChange(UINT nEventType,DWORD dwData);
 
 
BOOL CTestDlg::OnDeviceChange(UINT nEventType,DWORD dwData)
{
 
 DEV_BROADCAST_DEVICEINTERFACE * dbd =  (DEV_BROADCAST_DEVICEINTERFACE*) dwData;
    switch(nEventType)
    {
 
  case   DBT_DEVICEARRIVAL:
   MessageBox("Device arrival!");
   break;
  case   DBT_DEVICEQUERYREMOVE:
   //   Handle   device   removal   request
   MessageBox( "Device request remove!");
   break;
  case   DBT_DEVICEREMOVECOMPLETE:
   //   Handle   device   removal
   MessageBox(  "Device removal!" );
   break;
  default:
   MessageBox("others!");
   break;
  }  
       
   
    return  TRUE; 

}
第二种自己定义：
 
本代码可以监测USB状态的变化
启动VC，新建一个MFC的EXE程序，命名为USBListening，选择Dialog bassed,
其余默认，点击Finished
在绿字下面添加如下红色代码
 
 
在绿字下面添加如下红色代码/////////////////////////////////////////////////////////////////////////////// CUSBListeningDlg message handlers ＃i nclude "Dbt.h" ＃i nclude  ＃i nclude  #pragma comment(lib,"Rpcrt4.lib")PVOID g_hNotifyDevNode;void CUSBListeningDlg::RegisterForDevChange(HWND hDlg, PVOID *hNotifyDevNode){    DEV_BROADCAST_DEVICEINTERFACE *pFilterData =   (DEV_BROADCAST_DEVICEINTERFACE*)   _alloca(sizeof(DEV_BROADCAST_DEVICEINTERFACE));    ASSERT (pFilterData);  UUID GUID_CLASS_INPUT; UuidFromString((unsigned char*)"36FC9E60-C465-11CF-8056-444553540000", &GUID_CLASS_INPUT);     ZeroMemory(pFilterData, sizeof(DEV_BROADCAST_DEVICEINTERFACE));     pFilterData->dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE);    pFilterData->dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;    pFilterData->dbcc_classguid  = GUID_CLASS_INPUT;       *hNotifyDevNode = RegisterDeviceNotification(hDlg, pFilterData, DEVICE_NOTIFY_WINDOW_HANDLE);}//使用向导，添加DefWindowProc函数LRESULT CUSBListeningDlg::DefWindowProc(UINT message, WPARAM wParam, LPARAM lParam) {    switch (message)    {       case WM_DEVICECHANGE:        {            switch (wParam)            {            case DBT_DEVICEARRIVAL:            // Handle device arrival                    MessageBox("Handle device arrival");                    break;                case DBT_DEVICEQUERYREMOVE:                     // Handle device removal request                    MessageBox("Handle device removal request");                    break;                           case DBT_DEVICEREMOVECOMPLETE:                     // Handle device removal                   MessageBox("Handle device removal");                   break;            }        } }   return CDialog::DefWindowProc(message, wParam, lParam);}//在OnInitDialog函数中添加RegisterForDevChange函数BOOL CUSBListeningDlg::OnInitDialog(){ CDialog::OnInitDialog(); // Add "About..." menu item to system menu. // IDM_ABOUTBOX must be in the system command range. ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX); ASSERT(IDM_ABOUTBOX <0xF000); CMenu* pSysMenu = GetSystemMenu(FALSE); if (pSysMenu != NULL) {  CString strAboutMenu;  strAboutMenu.LoadString(IDS_ABOUTBOX);  if (!strAboutMenu.IsEmpty())  {   pSysMenu->AppendMenu(MF_SEPARATOR);   pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);  } } // Set the icon for this dialog.  The framework does this automatically //  when the application's main window is not a dialog SetIcon(m_hIcon, TRUE);   // Set big icon SetIcon(m_hIcon, FALSE);  // Set small icon  // TODO: Add extra initialization here RegisterForDevChange(m_hWnd,&g_hNotifyDevNode);  return TRUE;  // return TRUE  unless you set the focus to a control}