.Net二进制反序列化

Question

I am using BinaryFormatter to deserialize a file from another application. They share base libraries and most of the types serialized in the file are known.

However, there are also some types completely unknown and without no updatable match. I want to be able to discard deserialization for those cases.

Currently I am using a BinaryFormatter initialized with a SurrogateSelector and a SerializationBinder that I use to update to types affected by namespace changes in recent versions.

var formatter = new BinaryFormatter
{
    Context = streamingContext,
    SurrogateSelector = ss,
    Binder = new ProxiedRemappingSerializationBinder(),
    FilterLevel = TypeFilterLevel.Low
};

try
{
    var deserializedObject = formatter.Deserialize(contentsStream);
    ...
}

Specifically, the problem arises when, internally, the .NET Framework's tries to set values on an array of a known interface, but with unknown value type. The exception I get is: "System.InvalidCastException: Object cannot be stored in an array of this type."

So is there any way of making deserialization process discard these types (and just leave nulls) or even acting on the SerializationBinder somehow to prevent this exception?

Thanks in advance

** EDIT **

Besides the stack trace, the error is the typical InvalidcastException. I debugged within the .NET Framework, going through BinaryFormatter, BinaryObjectReader and ObjectManager, and it fails on the fixup phase (when it is assigning the actual values to the instances) on an array. Breaking in Array.cs, line 516, in InternalSetValue(&elemref,value); is where the exception gets raised.

I am using the Binder to change some types in de-serialization time to ones that my application knows (more recent version of the type), or to a dummy class. I understand why the exception happens, basically it is trying to set an incompatible object type on an interface array.

This type is a proxy type I dynamically generated to hold object info similar to this implementation: http://holistictendencies.wordpress.com/2009/11/16/creating-proxies-in-for-round-tripping-unknown-objects-in-c-server-apps/ So, since it doesn't implement the array interface, it fails. I just want the engine to discard these cases somehow.

Answer 1

I had a similar issue where I needed to BinaryFormatter.Deserialize() a class that I didn't have type information for but wanted to get some of the values from the properties from that object.

When it came time to deserialize that object .NET was throwing a SerializationException, complaining about the unknown assembly type.

I solved it by creating a custom class with the properties I needed (marked as Serializable) and then created another class that inherits from SerializationBinder:

public class MySerializationBinder : SerializationBinder
{
    public override Type BindToType(string assemblyName, string typeName)
    {
        if (assemblyName.Contains("namespace I don't have") && typeName.Contains("type info I don't have"))
                return typeof(MySubstitute);
        return Type.GetType($"{typeName}, {assemblyName}");
    }
}

[Serializable]
public class MySubstitute
{
    public string Name { get; set; }
    public string Title { get; set; }
}

Notice how if it isn't the type I am looking for I just return what was passed in.

Then when you create your BinaryFormatter set the binder property to an instance of your new custom binder:

 using (FileStream fs = new FileStream(openFileDialog1.FileName, FileMode.Open))
 {
       BinaryFormatter bf = new BinaryFormatter()   
      {
            Binder = new MySerializationBinder ()
       };                     
       mySubstitute = (MySubstitute)bf.Deserialize(fs);           
       fs.Close();
 }