Question

我目前正在C#编写代码，它需要通过套接字与VB6编写的程序进行通信。   当VB6程序没有运行时，我的C＃程序抛出一个SocketException。
我所做的是捕获异常，但我注意到它将继续抛出异常，直到VB6程序再次运行。  ReceiveFrom（...）方法处于无限循环中，因此当VB6程序再次运行时，它可以接收数据。  我想知道是否有更好的方法来解决这个问题。

C＃代码看起来像这样......

internal class SocketConnection : Connection
{
    private Socket socket;
    private EndPoint localEndPoint;
    private IPEndPoint remoteIPEndPoint;

    internal SocketConnection(int localPortNumber, IPAddress remoteIPAddress, int remotePortNumber)
    {
        IPEndPoint localIPEndPoint = new IPEndPoint(
            GetLocalIPAddress(),
            localPortNumber);

        socket = new Socket(
            localIPEndPoint.Address.AddressFamily,
            SocketType.Dgram,
            ProtocolType.Udp);

        socket.Bind(localIPEndPoint);

        localEndPoint = (EndPoint)localIPEndPoint;
        Thread receiver = new Thread(() => Receive());
        receiver.Start();

        remoteIPEndPoint = new IPEndPoint(remoteIPAddress, remotePortNumber);
    }

    private void Receive()
    {
        byte[] msg = new Byte[256];
        while (true)
        {
            try
            {
                socket.ReceiveFrom(msg, ref localEndPoint);
                buffer = Encoding.ASCII.GetString(msg).TrimEnd('\0');
            }
            catch (SocketException)
            {
                buffer = string.Empty;
            }
        }
    }
    private IPAddress GetLocalIPAddress()
    {
        var host = Dns.GetHostEntry(Dns.GetHostName());
        foreach (var ip in host.AddressList)
        {
            if (ip.AddressFamily == AddressFamily.InterNetwork)
            {
                return ip;
            }
        }
        throw new Exception("Local IP Address Not Found!");
    }

    protected override void Interrogate(string message)
    {
        socket.SendTo(Encoding.ASCII.GetBytes(message), remoteIPEndPoint);
    }
}

Answer 1

在调用ReceiveFrom之前，您应该检查套接字中是否有要读取的内容：

                int available = socket.Available;
                if (available > 0)
                {
                    socket.ReceiveFrom(msg, 0, Math.Min(msg.Length, available), SocketFlags.None, ref localEndPoint);
                    buffer = Encoding.ASCII.GetString(msg).TrimEnd('\0');
                }

SocketException在C＃中正确处理

1 个答案: