重写对象ToString方法

重写对象ToString方法，引入Newtonsoft.Json

public override string ToString()

    {

      JsonSerializerSettings settings = new JsonSerializerSettings();

      int num = ;

      settings.NullValueHandling = (NullValueHandling) num;

      return JsonConvert.SerializeObject((object) this, Formatting.Indented, settings);

    }

public override string ToString()

　　{

　　　　return JsonConvert.SerializeObject(this);

　　}