子类型无法识别序列化

Question

翻译：

  

尝试显示类型时发生错误   AnmialShelter.Animal

我有一个带有子类的Animal类，比如'horse'和'mouse'。

我把动物写成这样的XML：

private void writeToFile() 
    {
        DataContractSerializer dcs = new DataContractSerializer(typeof(Animal));

        using (FileStream f = new FileStream(Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + @"\file.xml",
               FileMode.Create, FileAccess.Write))
        {
            foreach (Animal a in animalList)
            {
                    dcs.WriteObject(f, a);
            }
        }
    }

当我尝试读取xml并将对象添加到动物列表时，错误如图所示。

private List<Animal> readFromFile()
{

   var myDeserializer = new XmlSerializer(typeof(Animal));

   using (var myFileStream = new FileStream(Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + @"\file.xml", FileMode.Open))
   {
       animalList = (List<Animal>)myDeserializer.Deserialize(myFileStream);
   }

    return animalList;
}