写入配置文件以及验证网络是否连通

        /// <summary>
        /// 向App。config写入字符串
        /// </summary>
        /// <param name="AppKey"></param>
        /// <param name="AppValue"></param>
        public static void SetValue(string ConnenctionString, string strKey)
        {
            XmlDocument doc = new XmlDocument();
            //获得配置文件的全路径
            string strFileName = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;

            //string strFileName = System.Windows.Forms.Application.StartupPath + "\App.config";
            doc.Load(strFileName);
            //找出名称为“add”的所有元素
            XmlNodeList nodes = doc.GetElementsByTagName("add");
            for (int i = 0; i < nodes.Count; i++)
            {
                //获得将当前元素的key属性
                XmlAttribute att = nodes[i].Attributes["key"];
                //根据元素的第一个属性来判断当前的元素是不是目标元素
                if (att.Value == strKey)
                {
                    //对目标元素中的第二个属性赋值
                    att = nodes[i].Attributes["value"];
                    att.Value = ConnenctionString;
                    break;
                }
            }
            //保存上面的修改
            doc.Save(strFileName);
        }

       /// <summary>
        /// 读出配置文件，验证网络是否连通
        /// </summary>
        public bool TestMethods()
        {
            conSql = new SqlConnection(CPDJConfig.ConfigurationManager.AppSettings["CONNSQLSTRYW"]);
            try
            {
                conSql.Open();
                return true;
            }
            catch (Exception e)
            {
                Console.WriteLine(e.StackTrace);
            }
            finally
            {
                conSql.Close();
            }
            return false;
        }