C# 保存配置文件，不存在则创建

 public static void SetAppConfig<T>(string appKey, T value, string description = "")
        {
            string appValue = "";
            Type t = typeof(T);
            if (t.Name == "Boolean")
            {
                appValue = bool.Parse(value.ToString()) ? "1" : "0";
            }
            else if (t.IsEnum)
            {
                appValue = Convert.ToInt32(value).ToString();
            }
            else
            {
              appValue = value.ToString();
            }
            XmlDocument xDoc = new XmlDocument();
            xDoc.Load(System.Windows.Forms.Application.ExecutablePath + ".config");

            XmlNode xNode = xDoc.SelectSingleNode("//appSettings");

            var xElem = (XmlElement)xNode.SelectSingleNode("//add[@key='" + appKey + "']");
            if (xElem != null)
            {
                xElem.SetAttribute("value", appValue);
            }
            else
            {
                if (!string.IsNullOrWhiteSpace(description))
                {
                    XmlComment comment = xDoc.CreateComment(description);
                    xNode.AppendChild(comment);
                }
                var xNewElem = xDoc.CreateElement("add");
                xNewElem.SetAttribute("key", appKey);
                xNewElem.SetAttribute("value", appValue);
                xNode.AppendChild(xNewElem);
            }
            xDoc.Save(System.Windows.Forms.Application.ExecutablePath + ".config");
        }