Qt MFC支持USB设备热插拔

一.某MFC开发代码：

BEGIN_MESSAGE_MAP(CHWDetectDlg, CDialog)
ON_WM_SYSCOMMAND()
ON_WM_PAINT()
ON_WM_QUERYDRAGICON()
ON_MESSAGE(WM_DEVICECHANGE, OnMyDeviceChange)
//}}AFX_MSG_MAP
ON_WM_CONTEXTMENU()
ON_COMMAND(ID_POPUP_DISABLE, OnPopupDisable)
END_MESSAGE_MAP()

//-----------处理函数---------------

LRESULT CHWDetectDlg::OnMyDeviceChange(WPARAM wParam, LPARAM lParam)
{
if ( DBT_DEVICEARRIVAL == wParam || DBT_DEVICEREMOVECOMPLETE == wParam ) {
PDEV_BROADCAST_HDR pHdr = (PDEV_BROADCAST_HDR)lParam;
PDEV_BROADCAST_DEVICEINTERFACE pDevInf;
PDEV_BROADCAST_HANDLE pDevHnd;
PDEV_BROADCAST_OEM pDevOem;
PDEV_BROADCAST_PORT pDevPort;
PDEV_BROADCAST_VOLUME pDevVolume;
switch( pHdr->dbch_devicetype ) {
case DBT_DEVTYP_DEVICEINTERFACE:
pDevInf = (PDEV_BROADCAST_DEVICEINTERFACE)pHdr;
UpdateDevice(pDevInf, wParam);
break;


case DBT_DEVTYP_HANDLE:
pDevHnd = (PDEV_BROADCAST_HANDLE)pHdr;
break;


case DBT_DEVTYP_OEM:
pDevOem = (PDEV_BROADCAST_OEM)pHdr;
break;


case DBT_DEVTYP_PORT:
pDevPort = (PDEV_BROADCAST_PORT)pHdr;
break;


case DBT_DEVTYP_VOLUME:
pDevVolume = (PDEV_BROADCAST_VOLUME)pHdr;
break;
}
}
return 0;
}

二.说明

WM_DEVICECHANGE的使用方式有二種，一種是透過WindowProc()的方式，一種是直接在程式裡加上OnDeviceChange()的函數，底下就先介紹第二種方式。

1. 新增消息 -- 在Dialog的.cpp裡加上藍色部份:
BEGIN_MESSAGE_MAP(CDeviceMonitorDlg, CDialog)
ON_WM_PAINT()
ON_WM_QUERYDRAGICON()
//}}AFX_MSG_MAP
ON_WM_DEVICECHANGE()
END_MESSAGE_MAP()

注意：不添加新增消息，就不能响应OnDeviceChange函数
2.新增一個函數 -- 這是Microsoft所提供的函數型態
DECLARE_MESSAGE_MAP()
public:
afx_msg BOOL OnDeviceChange(UINT nEventType,DWORD_PTR dwData);

3.函数內容的实现

下面是以USB插入响应为例

BOOL CCLMemTestDlg::OnDeviceChange( UINT nEventType, DWORD_PTR dwData )

{   

     switch(nEventType)

     {

     case DBT_DEVICEARRIVAL:

         UpdateUsbDeviceList();

         break;

     case DBT_DEVICEREMOVECOMPLETE:

         UpdateUsbDeviceList();

         UpdateWindow();

         break;

     }

     return TRUE;

}

三.

串口热拔插监听
关于串口热拔插监听，请更多地参考
《Qt中捕获Windows消息》
《USB转串口突然拔出检测解决方案》
《USB设备监控深入分析》


代码

1. #include <dbt.h>
   
2. 
   
3. bool WndTest::winEvent( MSG * message, long * result )
   
4. {
   
5.     if( WM_DEVICECHANGE == message->message ){
   
6.     }
   
7.     else
   
8.         goto ev_out;
   
9.    
   
10.     if( 0x8004 == message->wParam ){
    
11.         DEV_BROADCAST_PORT *vol = (DEV_BROADCAST_PORT*)message->lParam;
    
12.         QString str = QString::fromWCharArray(vol->dbcp_name); //获取要处理的串口名称
    
13. 
    
14.         if( 3 != vol->dbcp_devicetype )
    
15.             goto ev_out;
    
16.        
    
17.         if( m_serial ){
    
18.             if( str.size() > 0 ){
    
19.                 if( str.compare(cbComPort->currentText()) ==0 && m_connected ){ //比较串口名称，判定是否为当前使用的串口
    
20.                     closeport(); //关闭串口
    
21.                     qDebug()<<"close port:"<<str;
    
22.                 }
    
23.             }
    
24.         }
    
25.     }
    
26.     if( 0x8000 == message->wParam ){
    
27.         DEV_BROADCAST_PORT * vol = (DEV_BROADCAST_PORT*)message->lParam; //DEV_BROADCAST_VOLUME
    
28.         QString str = QString::fromWCharArray(vol->dbcp_name);
    
29.             if( str.size() > 0 ){
    
30.                     qDebug()<<"to open port:"<<str; //在DEBUG信息中输出要处理的串口名称
    
31.             }
    
32.        
    
33.     }
    
34. ev_out:
    
35.     return false;
    
36. }