如何在C#的视图模型上设置来自AppSettings的默认值？

<appSettings>
  <add key="DefaultSetting" value="DefaultValue" />
</appSettings>

using System.Configuration;

public class MyViewModel
{
    public MyViewModel()
    {
        string defaultValue = ConfigurationManager.AppSettings["DefaultSetting"];
        // 使用defaultValue进行后续操作
    }
}

public class MyViewModel
{
    public string MyProperty { get; set; }

    public MyViewModel()
    {
        string defaultValue = ConfigurationManager.AppSettings["DefaultSetting"];
        MyProperty = defaultValue;
    }
}