TStringList.savetofile使用utf8编码并不需要BOM

type
TUTF8EncodingNOBOM = class(TUTF8Encoding)
public
function GetPreamble: TBytes; override;
end;

{ TUTF8EncodingNOBOM }

function TUTF8EncodingNOBOM.GetPreamble: TBytes;
begin
Result := TBytes.Create();
end;