C# 使用UdpClient发送组播消息

实现的功能：

    1、服务端发送消息至预定义的组播地址   2、加入到组播组的客户端均能收到服务端发送的消息

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

服务端源码：

        private static IPAddress GroupAddress = IPAddress.Parse("224.100.0.1"); //定义组播地址
        private static int GroupPort =11000;   //定义发送组播时客户端的监听端口        
        private static void Send(String message)
        {
            UdpClient myUdpClient = new UdpClient(); //建立发送端的UdpClient实例
            IPEndPoint groupEP = new IPEndPoint(GroupAddress,GroupPort);//定义或设置IP地址与端口
            try
            {
                byte[] bytes = Encoding.UTF8.GetBytes(message);//将字符串转换成字节数组
                myUdpClient.Send(bytes, bytes.Length, groupEP);//使用UdpClient发送字节数据
                myUdpClient.Close();//关闭UDP连接
                MessageBox.Show("消息发送成功！");
            }
            catch (Exception e)
            {
                MessageBox.Show(e.ToString());
            }
           
        }
        private void button1_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();

        }

        private void btnSend_Click(object sender, EventArgs e)
        {
            string message = txttxnr.Text.Trim();
            Send(message);//调用Send方法发送消息
        }

客户端源码：

 private void MainForm_Load(object sender, EventArgs e)
        {
            Thread myThread = new Thread(ReceiveData);//使用线程启动ReceiveData()
            myThread.IsBackground = true;//是否为后台线程
            myThread.Start();//启动线程 

        }    
        private const int Groupport =11000; //声明组播端口
        private static readonly IPAddress GroupAddress = IPAddress.Parse("224.100.0.1");//定义组播地址
        private void ReceiveData() //循环接收UDP包，并将数据添加到listbox中
        {
            bool loop=true;
            UdpClient receiveUdpClient = new UdpClient(Groupport);//建立接收端的UdpClient实例，并定义端口
            IPEndPoint GroupEP = new IPEndPoint(GroupAddress,Groupport); //获取或设置IP地址与端口
            try
            {
            receiveUdpClient.JoinMulticastGroup(GroupAddress);//加入组播组
            receiveUdpClient.EnableBroadcast = true;//设置是否发送或接收广播数据包
            while (loop) //接收并显示消息内容
            {
       byte[] receiveBytes = receiveUdpClient.Receive(ref GroupEP);
       string receiveMessage = Encoding.UTF8.GetString(receiveBytes, 0, receiveBytes.Length);
       AddItem(lst_Receive, receiveMessage);//调用方法将消息内容发送到listbox中
       MessageBox.Show(receiveMessage);
             }
            //receiveUdpClient.Close();
            }
            catch (Exception e)
            {
                MessageBox.Show(e.ToString());
            }
        }
        delegate void AddItemDelegate(ListBox listbox, string text);
        private void AddItem(ListBox listbox, string text)
        {
            if (listbox.InvokeRequired)//在线程中调用创建于其他线程中的空间需要使用Invoke方法
            {
                AddItemDelegate d = AddItem;
                listbox.Invoke(d, new object[] { listbox, text });
            }
            else
            {
                listbox.Items.Add(text);
                listbox.SelectedIndex = listbox.Items.Count - 1;
                listbox.ClearSelected();
            }
        }