C#添加日志

     /// <summary>
         /// 记录日志
         /// </summary>
         /// <param name="msg"></param>
         protected void EndThing(string msg)
         {
             string DirPath = ApplicationPath + @"\Log\" + DateTime.Now.ToString("yyyyMMdd") + @"\";
             if (!Directory.Exists(DirPath))//如果不存在就创建file文件夹
             {
                 Directory.CreateDirectory(DirPath);
             }
             if (!File.Exists(DirPath + LogFileName + ".txt") || LogFileName != DateTime.Now.ToString("yyyy-MM-dd"))
             {
                 LogFileName = DateTime.Now.ToString("yyyy-MM-dd");
                 StreamWriter sw = File.CreateText(ApplicationPath + @"\Log\" + LogFileName + ".txt");
                 sw.WriteLine("=====================================================");
                 sw.WriteLine(msg + DateTime.Now);
                 sw.Close();

             }
             else
             {
                 StreamWriter sw = new StreamWriter(ApplicationPath + @"\Log\" + LogFileName + ".txt", true, Encoding.UTF8);
                 sw.WriteLine("=====================================================");
                 sw.WriteLine(msg + DateTime.Now);
                 sw.Close();
             }

         }