memorystream copyto network stream issues

问题

I'm having a problem with this code here.

using (MemoryStream ms = new MemoryStream())
{
    BinaryFormatter bf = new BinaryFormatter();
    bf.Serialize(ms,SerializableClassOfDoom);
    ms.Position = 0;
    byte[] messsize = BitConverter.GetBytes(ms.Length);
    ms.Write(messsize, 0, messsize.Length);
    NetworkStream ns = Sock.GetStream();
    ms.CopyTo(ns);
    //ms.Close();
}

I can't figure out what's happening here, or why it's not working. It seems like eather it doesn't copy, or it closes the network stream, or something.

I'm sorry, I've tried debugging it, but if anyone can see any obvious problem here, I would appreciate it.

By the way, the class serializes fine, and the MemoryStream contains the data, but for some reason doing a ms.CopyTo(ns) just doesn't seem to work?

Essentially what I want to do is serialize the class to the network stream, with the size of the serialized data preceding it. If someone has a better way to do this let me know!

回答1:

You are resetting the stream position at the wrong time.

In your case, you write the 'length' to the beginning of the stream.

The following should work:

using (MemoryStream ms = new MemoryStream())
{
    BinaryFormatter bf = new BinaryFormatter();
    bf.Serialize(ms,SerializableClassOfDoom);
    byte[] messsize = BitConverter.GetBytes(ms.Length);
    ms.Write(messsize, 0, messsize.Length);
    ms.Position = 0;
    NetworkStream ns = Sock.GetStream();
    ms.CopyTo(ns);
}

Update:

For writing 'length' to the start, use a temporary stream/byte[].

Example:

using (MemoryStream ms = new MemoryStream())
{
    BinaryFormatter bf = new BinaryFormatter();
    bf.Serialize(ms,SerializableClassOfDoom);
    byte[] data = ms.ToArray();
    byte[] messsize = BitConverter.GetBytes(ms.Length);
    ms.Position = 0;
    ms.Write(messsize, 0, messsize.Length);
    ms.Write(data, 0, data.Length);
    ms.Position = 0; // again!
    NetworkStream ns = Sock.GetStream();
    ms.CopyTo(ns);
}

Update 2:

More efficient way.

using (MemoryStream ms = new MemoryStream())
{
    BinaryFormatter bf = new BinaryFormatter();
    bf.Serialize(ms,SerializableClassOfDoom);
    byte[] messsize = BitConverter.GetBytes(ms.Length);
    NetworkStream ns = Sock.GetStream();
    ns.Write(messsize, 0, messsize.Length);
    ms.Position = 0; // not sure if needed, doc for CopyTo unclear
    ms.CopyTo(ns); 
}

回答2:

Maybe you need to rewind the memory stream to the beginning before calling CopyTo (use ms.Seek(0, SeekOrigin.Start))

回答3:

I don't see a real problem but i see a litte refactoring issue here.

Try using

Stream.Flush()
Stream.Close()

before finishing any Stream.

Also surround it with try-catch statements like this, to ensure closing and flushing happens even if there is an exception!

Stream s = new Stream();
try{
    s.Write();
}catch(Exception ex){
    //Oh god, we are doomed!
}finally{
    s.Flush();
    s.Close();
}

Your code would look like

NetworkStream ns = null;
using (MemoryStream ms = new MemoryStream())
{
    try{
        BinaryFormatter bf = new BinaryFormatter();
        bf.Serialize(ms,SerializableClassOfDoom);
        ms.Position = 0;
        byte[] messsize = BitConverter.GetBytes(ms.Length);
        ms.Write(messsize, 0, messsize.Length);
        ns = Sock.GetStream();
        ms.CopyTo(ns);
        //ms.Close();
    }catch(Exception ex){
        throw;
    }finally{
        ms.Flush();
        if(ns != null)
            ns.Flush();

        ms.Close();
    }
}

After this you should be able to find your problem.

来源：https://stackoverflow.com/questions/8307878/memorystream-copyto-network-stream-issues

标签

networking

memorystream

networkstream

binaryformatter