防止程序重复执行的单元

//工程引用此单元就能防止同时出现多个实例

unit

MultInst;

interface

uses

Windows ,Messages, SysUtils, Classes, Forms;

implementation

const

STR_UNIQUE    = '{2BE6D96E-827F-4BF9-B33E-8740412CDE96}'
;

MI_ACTIVEAPP  = 1
;  {激活应用程序}

MI_GETHANDLE  = 2
;  {取得句柄}

var

iMessageID    : Integer;

OldWProc      : TFNWndProc;

MutHandle     : THandle;

BSMRecipients : DWORD;

function

NewWndProc(Handle: HWND; Msg: Integer; wParam, lParam: Longint):

Longint; stdcall

;

begin

Result := 0
;

if

Msg = iMessageID then

begin

case

wParam of

MI_ACTIVEAPP: {激活应用程序}

if

lParam<>0
then

begin

{收到消息的激活前一个实例}

{为什么要在另一个程序中激活?}

{因为在同一个进程中SetForegroundWindow并不能把窗体提到最前}

if

IsIconic(lParam) then

OpenIcon(lParam)

else

SetForegroundWindow(lParam);

Application.Terminate; {终止本实例}

end

;

MI_GETHANDLE: {取得程序句柄}

begin

PostMessage(HWND(lParam), iMessageID, MI_ACTIVEAPP,

Application.Handle);

end

;

end

;

end

else

Result := CallWindowProc(OldWProc, Handle, Msg, wParam, lParam);

end

;

procedure

InitInstance;

begin

{取代应用程序的消息处理}

OldWProc    := TFNWndProc(SetWindowLong(Application.Handle, GWL_WNDPROC,

Longint(@NewWndProc)));

{打开互斥对象}

MutHandle := OpenMutex(MUTEX_ALL_ACCESS, False, STR_UNIQUE);

if

MutHandle = 0
then

begin

{建立互斥对象}

MutHandle := CreateMutex(nil

, False, STR_UNIQUE);

end

else

begin

Application.ShowMainForm  :=  False;

{已经有程序实例,广播消息取得实例句柄}

BSMRecipients := BSM_APPLICATIONS;

BroadCastSystemMessage(BSF_IGNORECURRENTTASK or

BSF_POSTMESSAGE,

@BSMRecipients, iMessageID, MI_GETHANDLE,Application.Handle);

end

;

end

;

initialization

{注册消息}

iMessageID  := RegisterWindowMessage(STR_UNIQUE);

InitInstance;

finalization

{还原消息处理过程}

if

OldWProc <> Nil then

SetWindowLong(Application.Handle, GWL_WNDPROC, LongInt(OldWProc));

{关闭互斥对象}

if

MutHandle <> 0
then

CloseHandle(MutHandle);

end

.