UDP通讯入门级示例（收发消息）

UDP通讯，介绍基础        private void btnReceive_Click(object sender, EventArgs e)
        {
            // 创建接收套接字
            IPAddress localIp = IPAddress.Parse(tbxlocalip.Text);
            IPEndPoint localIpEndPoint = new IPEndPoint(localIp, int.Parse(tbxlocalPort.Text));
            receiveUpdClient = new UdpClient(localIpEndPoint);
            Thread receiveThread = new Thread(ReceiveMessage);
            receiveThread.Start();
        }
        //接收消息方法
        private void ReceiveMessage()
        {
            IPEndPoint remoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);
            while (true)
            {
                try
                { // 关闭receiveUdpClient时此时会产生异常
                    byte[] receiveBytes = receiveUpdClient.Receive(ref remoteIpEndPoint);
                    string message = Encoding.Unicode.GetString(receiveBytes);
                    // 显示消息内容
                    ShowMessageforView(lstbxMessageView, string.Format("{0}[{1}]", remoteIpEndPoint, message));
                }
                catch
                {
                    break;
                }
            }
        }
        // 利用委托回调机制实现界面上消息内容显示
        delegate void ShowMessageforViewCallBack(ListBox listbox, string text);
        private void ShowMessageforView(ListBox listbox, string text)
        {
            if (listbox.InvokeRequired)
            {
                ShowMessageforViewCallBack showMessageforViewCallback = ShowMessageforView;
                listbox.Invoke(showMessageforViewCallback, new object[] { listbox, text });
            }
            else
            {
                lstbxMessageView.Items.Add(text);
                lstbxMessageView.SelectedIndex = lstbxMessageView.Items.Count - 1;
                lstbxMessageView.ClearSelected();
            }
        }

        private void btnSend_Click(object sender, EventArgs e)
        {
            if (tbxMessageSend.Text == string.Empty)
            {
                MessageBox.Show("发送内容不能为空", "提示");
                return;
            }
            // 选择发送模式
            if (chkbxAnonymous.Checked == true)
            {
                // 匿名模式(套接字绑定的端口由系统随机分配)
                sendUdpClient = new UdpClient(0);
            }
            else
            {
                // 实名模式(套接字绑定到本地指定的端口)
                IPAddress localIp = IPAddress.Parse(tbxlocalip.Text);
                IPEndPoint localIpEndPoint = new IPEndPoint(localIp, int.Parse(tbxlocalPort.Text));
                sendUdpClient = new UdpClient(localIpEndPoint);
            }
            Thread sendThread = new Thread(SendMessage);
            sendThread.Start(tbxMessageSend.Text);
        }
        //发送消息方法
        private void SendMessage(object obj)
        {
            string message = (string)obj;
            byte[] sendbytes = Encoding.Unicode.GetBytes(message);
            IPAddress remoteIp = IPAddress.Parse(tbxSendtoIp.Text);
            IPEndPoint remoteIpEndPoint = new IPEndPoint(remoteIp, int.Parse(tbxSendtoport.Text));
            sendUdpClient.Send(sendbytes, sendbytes.Length, remoteIpEndPoint);
            sendUdpClient.Close();
            // 清空发送消息框
            ResetMessageText(tbxMessageSend);
        }
        // 采用了回调机制