C#中读取app.config配置文件

    public class ConfigHelper
    {
        /// <summary>
        /// 读取app.config的appSetting
        /// </summary>
        /// <param name="key"></param>
        /// <returns></returns>
        public static string Read(string key)
        {
            return ConfigurationManager.AppSettings[key];
        }

        /// <summary>
        /// 写入app.config的appSetting
        /// </summary>
        /// <param name="key"></param>
        /// <param name="value"></param>
        /// <returns></returns>
        public static void Write(string key, string value)
        {
            Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
            config.AppSettings.Settings[key].Value = value;
            config.Save(ConfigurationSaveMode.Modified);
            ConfigurationManager.RefreshSection("appSettings");
        }

        /// <summary>
        /// app.config的appSettings中是否包含当前key
        /// </summary>
        /// <param name="key"></param>
        /// <returns></returns>
        public static bool Exists(string key)
        {
            Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
            return config.AppSettings.Settings.AllKeys.Contains(key);
        }
    }