Delphi单元文件之－防止程序重复执行

//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.