DataContractSerializer 和已知类型

我正在代码中序列化一个对象（不是通过 WCF 调用），并且我对已知类型有点沉迷（我已将它们与 WCF 一起使用，但没有将 DataContract 序列化器作为“独立”序列化器使用）

当我运行下面的代码时出现异常。我希望它运行时不会出现错误，因为我提供了已知类型。我在这里犯了什么错？

public class Parent {}
public class Child: Parent {}

// the code -- serialized is a serialized Child
// type is typeof(Parent) (I know it works if I pass typeof(Child), but isn't that what Known Types is all about??

// passing the known types seems to make no difference -- this only works if I pass typeof(Child) as the first param
var serializer = new DataContractSerializer(parentType, new Type[] {typeof(Child)});
object test = serializer.ReadObject(serialized);

好吧，我正经历着不断回答自己问题的日子。问题不在于反序列化，而在于序列化——您必须创建与反序列化器具有相同基本类型的序列化器（我已经根据子类型创建了序列化器）。就其价值而言，工作代码如下：

{
            var child = new Child();
            // here is where I went wrong before -- I used typeof(Child), with no known types to serialize
            var serializer = new DataContractSerializer(typeof(Parent), new Type[] { typeof(Child) });
            var stream = new MemoryStream();
            serializer.WriteObject(stream, child);
            stream.Position = 0;
            serializer = new DataContractSerializer(typeof(Parent), new Type[] { typeof(Child) });
            object test = serializer.ReadObject(stream);
            stream.Dispose();
            Console.WriteLine(test.ToString());
            Console.ReadLine();
}