如何使用Socket.SendAsync发送大数据

Question

private void ProcessReceive(SocketAsyncEventArgs e)
{
    // Check if the remote host closed the connection.
    if (e.BytesTransferred > 0)
    {
        if (e.SocketError == SocketError.Success)
        {
            Token token = e.UserToken as Token;
            token.SetData(e);

            Socket s = token.Connection;
            if (s.Available == 0)
            {
                Boolean willRaiseEvent = false;
                // GET DATA TO SEND
                byte[] sendBuffer = token.GetRetBuffer();
                // this.bufferSize IS SocketAsyncEventArgs buffer SIZE
                byte[] tempBuffer = new byte[this.bufferSize];
                int offset = 0;
                int size = (int)Math.Ceiling((double)sendBuffer.Length / (double)this.bufferSize);
                for (int i = 0; i < size - 1; i++)
                {
                    Array.Clear(tempBuffer, 0, this.bufferSize);
                    Array.Copy(sendBuffer, offset, tempBuffer, 0, this.bufferSize);
                    e.SetBuffer(tempBuffer, 0, this.bufferSize);
                    willRaiseEvent = s.SendAsync(e);
                    offset += this.bufferSize;
                }
                int remainSize = sendBuffer.Length - this.bufferSize * (size - 1);
                Array.Clear(tempBuffer, 0, this.bufferSize);
                Array.Copy(sendBuffer, offset, tempBuffer, 0, remainSize);
                e.SetBuffer(tempBuffer, 0, remainSize);
                willRaiseEvent = s.SendAsync(e);

                if (!willRaiseEvent)
                {
                    this.ProcessSend(e);
                }
            }
            else if (!s.ReceiveAsync(e))
            {
                // Read the next block of data sent by client.
                this.ProcessReceive(e);
            }
        }
        else
        {
            this.ProcessError(e);
        }
    }
    else
    {
        this.CloseClientSocket(e);
    }
}

此代码是从MSDN修改的

为什么在流通中,s.SendAsync(e)第二次执行,这将是错误的

异常:使用此SocketAsyncEventArgs实例已在进行异步套接字操作

如何发送大数据？

Answer 1

您必须等待Completed事件被引发才能进行另一次异步发送.不要忘记添加自己的事件处理程序,以便获得回调:

e.Completed += new EventHandler<SocketAsyncEventArgs>(SendCallback);

您可以使用我的异步HTTP客户端示例来为您的模型建模:

private void BeginSend()
{
    _clientState = EClientState.Sending;
    byte[] buffer = GetSomeData(); // gives you data for the buffer

    SocketAsyncEventArgs e = new SocketAsyncEventArgs();
    e.SetBuffer(buffer, 0, buffer.Length);
    e.Completed += new EventHandler<SocketAsyncEventArgs>(SendCallback);

    bool completedAsync = false;

    try
    {
        completedAsync = _socket.SendAsync(e);
    }
    catch (SocketException se)
    {
        Console.WriteLine("Socket Exception: " + se.ErrorCode + " Message: " + se.Message);
    }

    if (!completedAsync)
    {
        // The call completed synchronously so invoke the callback ourselves
        SendCallback(this, e);
    }

}

这是回调方法:

private void SendCallback(object sender, SocketAsyncEventArgs e)
{
    if (e.SocketError == SocketError.Success)
    {
        // You may need to specify some type of state and 
        // pass it into the BeginSend method so you don't start
        // sending from scratch
        BeginSend();
    }
    else
    {
        Console.WriteLine("Socket Error: {0} when sending to {1}",
               e.SocketError,
               _asyncTask.Host);
    }
}

回调完成后,您可以再次拨打电话BeginSend,直到您完成发送数据.