C# 創建或打開TXT文件並逐行寫入

/// <summary>
        /// 寫入記事本
        /// </summary>
        /// <param name="log">日志內容</param>
        /// <param name="filepath">文件路徑（含文件名）</param>
        /// <returns></returns>
        private static bool WriteTxt(string log, string filepath)
        {
            try
            {
                string folder = filepath.Substring(0, filepath.LastIndexOf('\\'));
                // 創建目錄
                if (Directory.Exists(folder) == false)
                {
                    Directory.CreateDirectory(folder);
                }
                // 當文件不存在時創建文件
                if (File.Exists(filepath) == false)
                {
                    FileStream fs = File.Create(filepath);
                    fs.Close();
                }
                // 寫入文件內容
                File.AppendAllText(filepath, "【" + DateTime.Now.ToString("yyyyMMdd HH:mm:ss") + "】" + log + "\r\n", Encoding.Default);
                return true;
            }
            catch
            {
                return false;
            }
        }