private static void UpdateAppConfig(string newKey, string newValue){    bool isModified = false;    foreach (string key in ConfigurationManager.AppSettings)    {        if (key == newKey)        {            isModified = true;        }    }    Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);    if (isModified)    {        config.AppSettings.Settings.Remove(newKey);    }    config.AppSettings.Settings.Add(newKey, newValue);    config.Save(ConfigurationSaveMode.Modified);    ConfigurationManager.RefreshSection("appSettings");}

 

之后直接用ConfigurationManager.AppSettings[key]读取就行了。