Delphi避免程序重复运行

全局量子和查找窗体的方法都用过，不太好，用下面这个

unit once;
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 orBSF_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 <> Nilthen
  SetWindowLong(Application.Handle, GWL_WNDPROC,LongInt(OldWProc));

 {关闭互斥对象}
 if MutHandle <> 0then CloseHandle(MutHandle);

end.

将这个unit加入项目，主窗体引用即可！BDS2006+win7下测试通过