WPF UDP Socket communication

Go directly to the code:

xmal:

<Window x:Class="UDPSocket.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="600" Width="800"  WindowStartupLocation="CenterScreen" Closing="MainWindow_Closing">
    <Grid>
        <GroupBox Header="发送数据" HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" Width="380" Height="545" Background="AliceBlue">
            <StackPanel>
                <RichTextBox Name="txtSendMssg" HorizontalAlignment="Left" Margin="5" VerticalAlignment="Top" Height="450" Width="355" Background="White"/>
                <Button Margin="50 10" Content="发送数据" Height="45" Click="btnSend_Click"/>
            </StackPanel>
        </GroupBox>
        <GroupBox Header="接收数据" HorizontalAlignment="Right" Margin="0,10,10,0" VerticalAlignment="Top" Width="380" Height="545" Background="AliceBlue">
            <StackPanel>
                <RichTextBox Name="txtRecvMssg" HorizontalAlignment="Left" Margin="5,5,5,5" VerticalAlignment="Top" Height="450" Width="355" Background="White"/>
                <Button Margin="50 10" Content="Receive data/Stop receiving" Height="45" Click="btnRecv_Click"/>
            </StackPanel>
        </GroupBox>
    </Grid>
</Window>

Backstage:

using System.Net.Sockets;
using System.Net;
using System.Threading;
using System.Windows.Threading;

namespace UDPSocket
{
    /// <summary>
    /// Interaction logic of MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        /// <summary>  
        /// Network service class for UDP sending  
        /// </summary>  
        private UdpClient udpcSend;
        /// <summary>  
        /// Network service class for UDP reception  
        /// </summary>  
        private UdpClient udpcRecv;

        /// <summary>  
        /// button: send data  
        /// </summary>  
        /// <param name="sender"></param>  
        /// <param name="e"></param>  
        private void btnSend_Click(object sender, EventArgs e)
        {
            TextRange tr = new TextRange(txtSendMssg.Document.ContentStart, txtSendMssg.Document.ContentEnd);
            if (string.IsNullOrWhiteSpace(tr.Text))
            {
                MessageBox.Show("Please enter the content to be sent first");
                return;
            }

            // send anonymously  
            //udpcSend = new UdpClient(0); // Automatically assign a local IPv4 address  
            // send real name  
            IPEndPoint localIpep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 1234); // Local IP, specified port number  
            udpcSend = new UdpClient(localIpep);
            Thread thrSend = new Thread(SendMessage);
            thrSend.Start(tr.Text);
        }

        /// <summary>  
        /// send Message  
        /// </summary>  
        /// <param name="obj"></param>  
        private void SendMessage(object obj)
        {
            string message = (string)obj;
            byte[] sendbytes = Encoding.Unicode.GetBytes(message);
            IPEndPoint remoteIpep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 7788); // IP address and port number to send to  
            udpcSend.Send(sendbytes, sendbytes.Length, remoteIpep);
            udpcSend.Close();
            ResetTextBox(txtSendMssg);
        }

        /// <summary>  
        /// Switch: true when listening to UDP packets, false otherwise  
        /// </summary>  
        bool IsUdpcRecvStart = false;
        /// <summary>  
        /// Thread: keep listening for UDP messages  
        /// </summary>  
        Thread thrRecv;

        /// <summary>  
        /// Button: receive data switch  
        /// </summary>  
        /// <param name="sender"></param>  
        /// <param name="e"></param>  
        private void btnRecv_Click(object sender, EventArgs e)
        {
            if (!IsUdpcRecvStart) // If not listening, start listening  
            {
                IPEndPoint localIpep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 7788); // Local IP and listening port number  
                udpcRecv = new UdpClient(localIpep);
                thrRecv = new Thread(ReceiveMessage);
                thrRecv.Start();
                IsUdpcRecvStart = true;
                ShowMessage(txtRecvMssg, "UDP listener started successfully");
            }
            else // If listening, stop listening  
            {
                thrRecv.Abort(); // This thread must be closed first, otherwise an exception will occur  
                udpcRecv.Close();
                IsUdpcRecvStart = false;
                ShowMessage(txtRecvMssg, "UDP listener closed successfully");
            }
        }

        /// <summary>  
        /// Receive data  
        /// </summary>  
        /// <param name="obj"></param>  
        private void ReceiveMessage(object obj)
        {
            IPEndPoint remoteIpep = new IPEndPoint(IPAddress.Any, 0);
            while (true)
            {
                try
                {
                    byte[] bytRecv = udpcRecv.Receive(ref remoteIpep);
                    string message = Encoding.Unicode.GetString(bytRecv, 0, bytRecv.Length);
                    ShowMessage(txtRecvMssg, string.Format("{0}[{1}]", remoteIpep, message.Trim()));
                }
                catch (Exception ex)
                {
                    ShowMessage(txtRecvMssg, ex.Message);
                    break;
                }
            }
        }

        // Add text to RichTextBox  
        delegate void ShowMessageDelegate(RichTextBox txtbox, string message);
        private void ShowMessage(RichTextBox txtbox, string message)
        {
            //if (txtbox.InvokeRequired)
            //{
            //    ShowMessageDelegate showMessageDelegate = ShowMessage;
            //    txtbox.Dispatcher.Invoke(showMessageDelegate, new object[] { txtbox, message });
            //}
            //else
            //{
            // //   txtbox.Text += message + "\r\n";
            //}  
            Console.WriteLine(message);
        }

        // Clear the text in the specified RichTextBox  
        delegate void ResetTextBoxDelegate(RichTextBox txtbox);
        private void ResetTextBox(RichTextBox txtbox)
        {
            //if (txtbox.InvokeRequired)
            //{
            //    ResetTextBoxDelegate resetTextBoxDelegate = ResetTextBox;
            //    txtbox.Dispatcher.Invoke(resetTextBoxDelegate, new object[] { txtbox });
            //}
            //else
            //{
            ////    txtbox.Text = "";
            //}  
        }

        /// <summary>  
        /// Close the program, force quit  
        /// </summary>  
        /// <param name="sender"></param>  
        /// <param name="e"></param>  
        private void MainWindow_Closing(object sender, System.ComponentModel.CancelEventArgs e)
        {
            Environment.Exit(0);
        }
    }
}