public void FileStream()        {            FileStream file;            string fileName=AppDomain.CurrentDomain.BaseDirectory+"\\log.txt";  //应用程序根地址            if (!File.Exists(fileName))            {                file = new FileStream(fileName, FileMode.Create);  //创建文件            }            else            {                file = new FileStream(fileName, FileMode.Append);  //文件后面追加文本            }            using(StreamWriter streamWriter = new StreamWriter(file))            {                streamWriter.WriteLine(DateTime.Now.ToString());                streamWriter.Flush(); //将缓存数据写入流，并清除当前缓存数据            }        }