anti_moreapps.~pas

罗小平<<delphi精要>>一书源码

unit Anti_MoreApps;

interface

  function HaveApp(AppID: String): Boolean;
  {在工程文件中写：
  if HavePrevInst(AppID: String) then Exit;
  Application.Initialize;
  //AppID: 不同的应用程序中应该不同,
  //所以推荐用Ctrl+Shift+G生成，形如'09A81772-BAA8-41D0-A93A-600DCAEBF058';
  .......}
  
implementation

uses Windows;

var
  HMutex: THandle;

function HaveApp(AppID: String): Boolean;
begin
  Result := False;
  HMutex := OpenMutex(MUTEX_ALL_ACCESS, False, PChar(AppID));
  if HMutex = 0 then
    HMutex := CreateMutex(nil, False, PChar(AppID))
  else Result := True;
end;

initialization
finalization
  if HMutex <> 0 then CloseHandle(HMutex);

end.