c#窗体应用程序怎么保存_importedfile用什么打开

/// <summary>
        /// 另存文件对话框
        /// </summary>
        /// <param name="fileName">想命名的文件名</param>
        /// <returns></returns>
        public static string SaveFileDialog(string fileName )
        {
            string selectPath = "";
            bool isFileOk = false;
            System.Windows.Forms.SaveFileDialog folderDialog = new System.Windows.Forms.SaveFileDialog();
            folderDialog.FileName = fileName;
            folderDialog.Filter = "(*.png)|*.png"; folderDialog.FileOk += (s,e)=> { isFileOk = true; };
            folderDialog.ShowDialog();
            if (isFileOk)
            {
                if (!String.IsNullOrEmpty(folderDialog.FileName))
                {
                    selectPath = folderDialog.FileName;
                }
            }
            else
            {
                selectPath = null;
            }
            return selectPath;
        }