function HttpEncode(S:AnsiString):string;
var
  P:^Byte;
  I:Cardinal;
begin
  Result:=\'\';
  P:=@S[1];
  Result:=Format(\'%%%x\',[Ord(P^)]);
  for I := 1 to Length(S)-1 do
  begin
    Inc(P);
    Result:=Format(\'%s%%%x\',[Result,Ord(P^)]);
  end;
end;


function HttpDecode(str:AnsiString): string;
var
  List: TStrings;
  tmpStr: AnsiString;
  i: Integer;
begin
  List := TStringList.Create;
  ExtractStrings([\'%\'], [\'%\'], PChar(str), List);
  SetLength(tmpStr, List.Count);
  for i := 0 to List.Count - 1 do
  Byte(tmpStr[i+1]) := StrToInt(\'$\' + List[i]);
  List.Free;
  Result := Utf8Decode(tmpStr);

end;

procedure TuMain.btnStartClick(Sender: TObject);
    var
    i :integer;
   s: string;
begin
  s:=\'衣服\';
  s:=HttpEncode(AnsiToUtf8(s));
  showmessage(s);                                            //显示 %E8%A1%A3%E6%9C%8D
  s := HttpDecode(s);
  showmessage(s);
end;