string folder = string.Format(@"D:\\{0}\\{1}", DateTime.Now.ToString("yyyy"), DateTime.Now.ToString("MM"));
            //判断文件夹是否存在
            if (!Directory.Exists(folder))
            {
                Directory.CreateDirectory(folder);
            }
            try
            {
                File.WriteAllText(string.Format("{0}\\{1}.txt", folder, DateTime.Now.ToString("yyyyMMdd")), "测试信息向文件中覆盖写入信息", Encoding.UTF8);

                //在将文本写入文件前，处理文本行
                //StreamWriter一个参数默认覆盖
                //StreamWriter第二个参数为false覆盖现有文件，为true则把文本追加到文件末尾
                using (StreamWriter file = new StreamWriter(string.Format("{0}\\{1}.txt", folder, DateTime.Now.ToString("dd")), true))
                {
                    file.WriteLine("测试信息向文件中追加");//直接追加文件末尾，不换行
                    file.WriteLine("---------------------------------");
                    file.WriteLine();// 直接追加文件末尾，换行
                    file.Close();
                }
            }
            catch (Exception)
            {
                throw;
            }

DirectoryInfo dir = new DirectoryInfo(path);
            if (dir.Exists)
            {
                DirectoryInfo[] childs = dir.GetDirectories();
                foreach (DirectoryInfo child in childs)
                {
                    child.Delete(true);
                }
                dir.Delete(true);
            }