Help needed with the most trivial protobuf-net example

问题

Observe the following trivial piece of code:

  [ProtoContract]
  public class B
  {
    [ProtoMember(1)] public int Y;
  }

  [ProtoContract]
  public class C
  {
    [ProtoMember(1)] public int Y;
  }

  class Program
  {
    static void Main()
    {
      var b = new B { Y = 2 };
      var c = new C { Y = 4 };
      using (var ms = new MemoryStream())
      {
        Serializer.Serialize(ms, b);
        Serializer.Serialize(ms, c);
        ms.Position = 0;
        var b2 = Serializer.Deserialize<B>(ms);
        Debug.Assert(b.Y == b2.Y);
        var c2 = Serializer.Deserialize<C>(ms);
        Debug.Assert(c.Y == c2.Y);
      }
    }
  }

The first assertion fails! Each Serialize statement advances the stream position by 2, so in the end ms.Position is 4. However, after the first Deserialize statement, the position is set to 4, rather than 2! In fact, b2.Y equals 4, which should be the value of c2.Y!

There is something absolutely basic, that I am missing here. I am using protobuf-net v2 r383.

Thanks.

EDIT

It must be something really stupid, because it does not work in v1 either.

回答1:

You have to use the SerializeWithLengthPrefix/ DeserializeWithLengthPrefix methods in order to retrieve a single object from you stream. this should be working:

var b = new B { Y = 2 };
var c = new C { Y = 4 };
using (var ms = new MemoryStream())
{
    Serializer.SerializeWithLengthPrefix(ms, b,PrefixStyle.Fixed32);
    Serializer.SerializeWithLengthPrefix(ms, c, PrefixStyle.Fixed32);
    ms.Position = 0;
    var b2 = Serializer.DeserializeWithLengthPrefix<B>(ms,PrefixStyle.Fixed32);
    Debug.Assert(b.Y == b2.Y);
    var c2 = Serializer.DeserializeWithLengthPrefix<C>(ms, PrefixStyle.Fixed32);
    Debug.Assert(c.Y == c2.Y);
}

来源：https://stackoverflow.com/questions/6107832/help-needed-with-the-most-trivial-protobuf-net-example

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