用程序修改配置文件

        [HttpPost]
        public ActionResult SaveSetting(string key, string value)
        {
            if (!string.IsNullOrWhiteSpace(key) && !string.IsNullOrWhiteSpace(value)
                && ConfigurationManager.AppSettings.AllKeys.Contains(key))
            {
                //ConfigurationManager.AppSettings.Set(key, value);                
                
                //var config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);  //winform之类应用程序的修改方式

                var config = WebConfigurationManager.OpenWebConfiguration("~");  //web应用程序修改

                config.AppSettings.Settings[key].Value = value;
                config.Save();
            }

            return RedirectToAction("Index");
        }