delphi 获取USB口拔出和插入的状态
unit USBDeviceNotify;
//USB Device arrival or remove
interface
uses
Windows, Messages, SysUtils, Classes, Forms;
type
PDevBroadcastHdr = ^DEV_BROADCAST_HDR;
DEV_BROADCAST_HDR = packed record
dbch_size: DWORD;
dbch_devicetype: DWORD;
dbch_reserved: DWORD;
end;
PDevBroadcastDeviceInterface = ^DEV_BROADCAST_DEVICEINTERFACE;
DEV_BROADCAST_DEVICEINTERFACE = record
dbcc_size: DWORD;
dbcc_devicetype: DWORD;
dbcc_reserved: DWORD;
dbcc_classguid: TGUID;
dbcc_name: short;
end;
const
GUID_DEVINTERFACE_USB_DEVICE: TGUID = '{A5DCBF10-6530-11D2-901F-00C04FB951ED}';
DBT_DEVICEARRIVAL = $8000; // system detected a new device
DBT_DEVICEREMOVECOMPLETE = $8004; // device is gone
DBT_DEVTYP_DEVICEINTERFACE = $00000005; // device interface class
type
TUSBDeviceEvent = procedure(Sender: TObject; pDeviceData: PDevBroadcastDeviceInterface) of object;
TUSBDeviceNotify = class(TComponent)
private
FWindowHandle: HWND;
FOnUSBArrival: TUSBDeviceEvent;
FOnUSBRemove: TUSBDeviceEvent;
procedure WndProc(var Msg: TMessage);
function USBRegister: Boolean;
protected
procedure WMDeviceChange(var Msg: TMessage); dynamic;
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
published
property OnUSBArrival: TUSBDeviceEvent read FOnUSBArrival write FOnUSBArrival;
property OnUSBRemove: TUSBDeviceEvent read FOnUSBRemove write FOnUSBRemove;
end;
implementation
constructor TUSBDeviceNotify.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FWindowHandle := AllocateHWnd(WndProc);
USBRegister;
end;
destructor TUSBDeviceNotify.Destroy;
begin
DeallocateHWnd(FWindowHandle);
inherited Destroy;
end;
procedure TUSBDeviceNotify.WndProc(var Msg: TMessage);
begin
if (Msg.Msg = WM_DEVICECHANGE) then
begin
try
WMDeviceChange(Msg);
except
Application.HandleException(Self);
end;
end
else
Msg.Result := DefWindowProc(FWindowHandle, Msg.Msg, Msg.wParam, Msg.lParam);
end;
procedure TUSBDeviceNotify.WMDeviceChange(var Msg: TMessage);
var
devType: Integer;
Datos: PDevBroadcastHdr;
pData: PDevBroadcastDeviceInterface;
begin
if (Msg.wParam = DBT_DEVICEARRIVAL) or (Msg.wParam = DBT_DEVICEREMOVECOMPLETE) then
begin
Datos := PDevBroadcastHdr(Msg.lParam);
devType := Datos^.dbch_devicetype;
if devType = DBT_DEVTYP_DEVICEINTERFACE then
begin // USB Device
pData := PDevBroadcastDeviceInterface(Msg.LParam);
if Msg.wParam = DBT_DEVICEARRIVAL then
begin
if Assigned(FOnUSBArrival) then
FOnUSBArrival(Self, pData);
end
else
begin
if Assigned(FOnUSBRemove) then
FOnUSBRemove(Self, pData);
end;
end;
end;
end;
function TUSBDeviceNotify.USBRegister: Boolean;
var
dbi: DEV_BROADCAST_DEVICEINTERFACE;
Size: Integer;
r: Pointer;
begin
Result := False;
Size := SizeOf(DEV_BROADCAST_DEVICEINTERFACE);
ZeroMemory(@dbi, Size);
dbi.dbcc_size := Size;
dbi.dbcc_devicetype := DBT_DEVTYP_DEVICEINTERFACE;
dbi.dbcc_reserved := 0;
dbi.dbcc_classguid := GUID_DEVINTERFACE_USB_DEVICE;
dbi.dbcc_name := 0;
r := RegisterDeviceNotification(FWindowHandle, @dbi,
DEVICE_NOTIFY_WINDOW_HANDLE
);
if Assigned(r) then
Result := True;
end;
end.