关键代码：

        public static string GetAppSettingsValue(string key)        {            ConfigurationManager.RefreshSection("appSettings");            return ConfigurationManager.AppSettings[key] ?? string.Empty;        }        public static bool UpdateAppSettings(string key, string value)        {            var _config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);            if (!_config.HasFile)            {                throw new ArgumentException("程序配置文件缺失！");            }            KeyValueConfigurationElement _key = _config.AppSettings.Settings[key];            if (_key == null)                _config.AppSettings.Settings.Add(key, value);            else                _config.AppSettings.Settings[key].Value = http://www.mamicode.com/value;            _config.Save(ConfigurationSaveMode.Modified);            return true;        }

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[C#]appSettings节点读取与修改