delphi调用百度API获取token

procedure TForm1.btn_getTokenClick(Sender: TObject);
var
  sendData: string;
  url: string;
  ss: TStringStream;
  jsonData: isuperobject;
begin
  url := 'https://aip.baidubce.com/oauth/2.0/token';
  sendData := 'grant_type=client_credentials&client_id=' + Self.cxTextEdit_clientID.Text + '&client_secret=' + Self.cxTextEdit_clientSecret.Text;

  try
    ss := TStringStream.Create('', TEncoding.UTF8);
    ss.WriteString(sendData);
    self.NetHTTPClient1.Accept := 'text/html, application/xhtml+xml, */*';
    self.NetHTTPClient1.ContentType := 'application/x-www-form-urlencoded'; //application/json
    self.NetHTTPClient1.AcceptEncoding := 'UTF-8';
    ss.Position := 0;

    jsonData := SO(NetHTTPClient1.Post(url, ss).ContentAsString(tencoding.UTF8));

    if Assigned(jsonData['access_token']) then
    begin
      cxMemo1.Clear;
      cxMemo1.Lines.Add(jsonData['access_token'].AsString);
      access_token := jsonData['access_token'].AsString;
    end;

  finally
    ss.Free;
  end;

end;