.net Web.config工具类

   public static class AppConfigUtil
    {

         public static string GetAppConfig(string key)
        {
            Configuration config = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~");
            return config.AppSettings.Settings[key].Value;
        }


        /// <summary>  
        /// 在web.config文件中appSettings配置节增加一对键值对  
        /// </summary>  
        /// <param name="key"></param>  
        /// <param name="val"></param>
        public static void UpdateAppConfig(string key, string val)
        {
            Configuration config = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~");
            bool exist = config.AppSettings.Settings.AllKeys.Contains(key);
            if (exist)
            {
                config.AppSettings.Settings.Remove(key);
            }
            config.AppSettings.Settings.Add(key, val);
            config.Save(ConfigurationSaveMode.Modified);
            ConfigurationManager.RefreshSection("appSettings");
        }
    }