/// <summary>
/// 修改配置文件中某项的值
/// </summary>
/// <param name="key">appSettings的key</param>
/// <param name="value">appSettings的Value</param>
public static void SetConfig(string key, string value)
{
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

if (config.AppSettings.Settings[key] != null)
config.AppSettings.Settings[key].Value = value;
else
config.AppSettings.Settings.Add(key, value);
config.Save(ConfigurationSaveMode.Modified);
ConfigurationManager.RefreshSection("appSettings");
}