using System;using System.Net;using System.Net.Sockets;using System.Text;using System.Threading;using System.Windows.Forms;namespace UDPBroadcast{    /// 
    /// 在界面上，用户可以设置本地进程的IP地址和端口号，并将地址加入某个组播组；    /// 可以输入发送消息的目的组的地址，并且勾选“广播”复选框将采用广播的方式发送信息    /// 在界面上点击“接受按钮”就启动接收线程，这样程序就可以接收广播或组播的信息    /// 
    public partial class UdpBroadcasefrm : Form    {        private UdpClient sendUdpClient;        private UdpClient receiveUdpClient;        // 组播IP地址        IPEndPoint broadcastIpEndPoint;        public UdpBroadcasefrm()        {            InitializeComponent();            IPAddress[] ips = Dns.GetHostAddresses(Dns.GetHostName());            tbxlocalip.Text = ips[5].ToString();            tbxlocalport.Text = "8002";            // 默认组,组播地址是有范围            // 具体关于组播和广播的介绍参照我上一篇博客UDP编程            // 本地组播组            tbxGroupIp.Text = "224.0.0.1";            // 发送到的组播组            tbxSendToGroupIp.Text = "224.0.0.1";        }        // 设置加入组        private void chkbxJoinGtoup_Click(object sender, EventArgs e)        {            if (chkbxJoinGtoup.Checked == true)            {                tbxGroupIp.Enabled = false;            }            else            {                tbxGroupIp.Enabled = true;                tbxGroupIp.Focus();            }        }        // 选择发送模式后设置        private void chkbxBroadcast_Click(object sender, EventArgs e)        {            if (chkbxBroadcast.Checked == true)            {                tbxSendToGroupIp.Enabled = false;            }            else            {                tbxSendToGroupIp.Enabled = true;                tbxSendToGroupIp.Focus();            }        }        // 发送消息        private void btnSend_Click(object sender, EventArgs e)        {            if (tbxMessageSend.Text == "")            {                MessageBox.Show("消息内容不能为空！","提示");                return;            }            // 根据选择的模式发送信息            if (chkbxBroadcast.Checked == true)            {                // 广播模式(自动获得子网中的IP广播地址)                broadcastIpEndPoint = new IPEndPoint(IPAddress.Broadcast, 8002);            }            else            {                // 组播模式                broadcastIpEndPoint = new IPEndPoint(IPAddress.Parse(tbxSendToGroupIp.Text), 8002);            }            // 启动发送线程发送消息            Thread sendThread = new Thread(SendMessage);            sendThread.Start(tbxMessageSend.Text);        }        // 发送消息        private void SendMessage(object obj)        {            string message = obj.ToString();            byte[] messagebytes = Encoding.Unicode.GetBytes(message);            sendUdpClient = new UdpClient();            // 发送消息到组播或广播地址            sendUdpClient.Send(messagebytes, messagebytes.Length, broadcastIpEndPoint);            sendUdpClient.Close();                        // 清空编辑消息框            ResetMessageText(tbxMessageSend);        }        // 利用委托回调机制来实现界面上的消息清空操作        delegate void ResetMessageTextCallBack(TextBox textbox);        private void ResetMessageText(TextBox textbox)        {            if (textbox.InvokeRequired)            {                ResetMessageTextCallBack resetMessageCallback = ResetMessageText;                textbox.Invoke(resetMessageCallback, new object[] { textbox });            }            else            {                textbox.Clear();                textbox.Focus();            }        }        // 接收消息        private void btnReceive_Click(object sender, EventArgs e)        {            chkbxJoinGtoup.Enabled = false;            // 创建接收套接字            IPAddress localIp = IPAddress.Parse(tbxlocalip.Text);            IPEndPoint localIpEndPoint = new IPEndPoint(localIp, int.Parse(tbxlocalport.Text));            receiveUdpClient = new UdpClient(localIpEndPoint);            // 加入组播组            if (chkbxJoinGtoup.Checked == true)            {                receiveUdpClient.JoinMulticastGroup(IPAddress.Parse(tbxGroupIp.Text));                receiveUdpClient.Ttl = 50;            }            // 启动接受线程            Thread threadReceive = new Thread(ReceiveMessage);            threadReceive.Start();        }        // 接受消息方法        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 = receiveUdpClient.Receive(ref remoteIpEndPoint);                    string receivemessage = Encoding.Unicode.GetString(receiveBytes);                    // 显示消息内容                    ShowMessage(lstMessageBox, string.Format("{0}[{1}]", remoteIpEndPoint, receivemessage));                }                catch                {                    break;                }            }        }        // 通过委托回调机制显示消息内容        delegate void ShowMessageCallBack(ListBox listbox,string text);        private void ShowMessage(ListBox listbox, string text)        {            if (listbox.InvokeRequired)            {                ShowMessageCallBack showmessageCallback = ShowMessage;                listbox.Invoke(showmessageCallback, new object[] { listbox, text });            }            else            {                listbox.Items.Add(text);                listbox.SelectedIndex = listbox.Items.Count - 1;                listbox.ClearSelected();            }        }        // 清空消息列表        private void btnClear_Click(object sender, EventArgs e)        {            lstMessageBox.Items.Clear();        }        // 停止接收        private void btnStop_Click(object sender, EventArgs e)        {            chkbxJoinGtoup.Enabled =true;            receiveUdpClient.Close();        }           }}