public void writetxt(string content)        {            string filePath = Server.MapPath("data.txt");            int len = content.Length;            byte[] inputByts = new byte[len];            inputByts = Encoding.GetEncoding("utf-8").GetBytes(content);            System.IO.FileStream fs = new System.IO.FileStream(filePath, System.IO.FileMode.OpenOrCreate);            fs.Seek(0, System.IO.SeekOrigin.End);            fs.Write(inputByts, 0, inputByts.Length);            fs.Close();//关闭流        }