Question

I just went through a YouTube tutorial on tcpip servers and clients and was using the code from it: https://www.youtube.com/watch?v=uXFso7xSSWk both part 1 and part 2. I have redone the code twice and have made sure that everything is the same. Whenever I run the server I get the error "SocketException was unhandled" at the line 'tcpListener.Start();' in the following method.

private void TcpServerRun()
        {
            TcpListener tcpListener = new TcpListener(IPAddress.Any, 5004);
            tcpListener.Start();
            updateUI("Listening");
            while (true)
            {
                TcpClient client = tcpListener.AcceptTcpClient();
                updateUI("Connected");
                Thread tcpHandlerThread = new Thread (new ParameterizedThreadStart(tcpHandler));
                tcpHandlerThread.Start(client);
            }
        }

I also get the same error when I run the client, but it is at the line 'client.Connect(IPAddress.Parse("10.3.29.252"), 5004);' in the following method:

private void ConnectAsClient()
        {
            TcpClient client = new TcpClient();
            client.Connect(IPAddress.Parse("10.3.29.252"), 5004);
            NetworkStream stream = client.GetStream();
            string s = "Hello from client";
            byte[] message = Encoding.ASCII.GetBytes(s);
            stream.Write(message, 0, message.Length);
            updateUI("Message send");
            stream.Close();
            client.Close();
        }

Any and all help is much appreciated. I am pretty new to coding and very new to c# so I am sorry for anything that maybe unclear.

Here is the entire code for the server:

namespace TcpServerTutorial
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void bStartServer_Click(object sender, EventArgs e)
        {
            Thread tcpServerRunThread = new Thread(new ThreadStart(TcpServerRun));
            tcpServerRunThread.Start();
            TcpServerRun();
        }

        private void TcpServerRun()
        {
            TcpListener tcpListener = new TcpListener(IPAddress.Any, 5004);
            tcpListener.Start();
            updateUI("Listening");
            TcpClient client = tcpListener.AcceptTcpClient();
            while (true)
            {
                TcpClient client = tcpListener.AcceptTcpClient();
                updateUI("Connected");
                Thread tcpHandlerThread = new Thread (new ParameterizedThreadStart(tcpHandler));
                tcpHandlerThread.Start(client);
            }


        }

        private void tcpHandler(object client)
        {
            TcpClient mClient = (TcpClient)client;
            NetworkStream stream = mClient.GetStream();
            byte[] message = new byte[1024];
            stream.Read(message, 0, message.Length);
            updateUI("New Message = " + Encoding.ASCII.GetString(message));
            stream.Close();
            mClient.Close();
        }

        private void updateUI(string s)
        {
            Func<int> del = delegate()
            {
                textBox1.AppendText(s + System.Environment.NewLine);
                return 0;
            };
            Invoke(del);
        }
    }
}

Answer 1

宾果。看看这段代码：

    private void bStartServer_Click(object sender, EventArgs e)
    {
        // Called once when the thread starts
        Thread tcpServerRunThread = new Thread(new ThreadStart(TcpServerRun));
        tcpServerRunThread.Start();
        // Called again here
        TcpServerRun();
    }

TCPServerRun()方法被调用两次：一次是在线程启动时，然后在启动线程后立即通过显式调用再次调用（或者甚至可能以相反的顺序）。这是SocketException发生的调用，因为服务器已经启动。删除第二个参考，你的问题应该解决;在你的客户端寻找类似的情况。

C# SocketException was unhandled

1 个答案: