delphi如何计算一个目录的大小

function GetDirectorySize(const ADirectory: string): Integer;
var
Dir: TSearchRec;
Ret: integer;
Path: string;
begin
Result := 0;
Path := ExtractFilePath(ADirectory);
Ret := Sysutils.FindFirst(ADirectory, faAnyFile, Dir);
if Ret <> NO_ERROR then exit;
try
while ret=NO_ERROR do
begin
inc(Result, Dir.Size);
if (Dir.Attr in [faDirectory]) and (Dir.Name[1] <> .) then
Inc(Result, GetDirectorySize(Path + Dir.Name + \*.*));
Ret := Sysutils.FindNext(Dir);
end;
finally
Sysutils.FindClose(Dir);
end;
end;