需要引用单元　EncdDecd ，Xe验证通过。

function EncodeFile(const FileName: string): AnsiString;

var

   stream: TMemoryStream;

begin

   stream := TMemoryStream.Create;

   try

    stream.LoadFromFile(Filename);

    result := EncodeBase64(stream.Memory, stream.Size);

   finally

    stream.Free;

   end;

end;