[C#] 建立UDP連接、發送廣播

說明：

　　通過建立本地UdpClient與遠程UdpClient進行通訊，亦可直接發送到其他已存在的遠程端。

　　基本原理：構建一個本地的udpcSend實例，開啟多線程進行監聽，然后再發送廣播。

　　案例有字節數組與十六進制字符串相互轉換的方法。

 

一、案例源碼

　　窗體的主要代碼：FrmMain.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace NetworkService
{
    public partial class FrmMain : Form
    {
        public FrmMain()
        {
            InitializeComponent();

            //string msg = "FF FB 0F";
            //byte[] bytes = Encoding.Default.GetBytes(msg);
            

            //string res = "";
            //for (int i = 0; i < bytes.Length; i++)
            //{
            //    res += bytes[i].ToString();
            //}
            //MessageBox.Show(res);


        }

        //本地收發UDPClient實例
        private UdpClient udpcSend;
        private UdpClient udpcRecv;
        private bool isLocalConneted = false;//本地是否已連接
        private Thread thrRecv;//本地監聽接收線程

        /// <summary>
        /// 【構建本地連接】
        ///  20181021
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnConnect_Click(object sender, EventArgs e)
        {
            if (cbProtocol.SelectedIndex != 0)
            {
                MessageBox.Show("請暫時選擇UDP協議！", "系統提示");
                return;
            }

            if (string.IsNullOrWhiteSpace(tbLocalIP.Text) || string.IsNullOrWhiteSpace(tbLocalPort.Text))
            {
                MessageBox.Show("請填寫本地IP和端口", "系統提示");
                return;
            }


            if (!isLocalConneted)//構建本地連接
            {
                IPEndPoint localIpep = new IPEndPoint(IPAddress.Parse(tbLocalIP.Text), Convert.ToInt32(tbLocalPort.Text));
                udpcSend = new UdpClient(localIpep);

                btnConnect.Text = "斷開";
                isLocalConneted = true;

                //啟動監聽接收信息
                BeginListenRecv();
            }
            else//斷開本地連接
            {
                //關閉監聽線程
                thrRecv.Abort();
                udpcRecv.Close();

                udpcSend.Close();
                btnConnect.Text = "連接";
                isLocalConneted = false;


                ShowMessage(tbRecvMsg, "[OS]:UDP監聽已成功關閉");
            }
        }

        
        
        /// <summary>
        /// 【開始監聽】
        ///  20181021
        /// </summary>
        private void BeginListenRecv()
        {
            udpcRecv = udpcSend;//接收與發送使用同一個實例

            thrRecv = new Thread(ReceiveMessage);
            thrRecv.Start();

            ShowMessage(tbRecvMsg, "[OS]:Local UDP 監聽已成功啟動");

        }

        /// <summary>
        /// 【接收信息】
        ///  20181021
        /// </summary>
        private void ReceiveMessage()
        {
            IPEndPoint remoteIpep = new IPEndPoint(IPAddress.Any, 0);//接收任何來源的信息
            while (true)
            {
                byte[] byteRecv = udpcRecv.Receive(ref remoteIpep);
                string message = ByteArrayToHexStringNoBlank(byteRecv);

                //remoteIpep.Address.ToString() 獲取發送源的IP
                ShowMessage(tbRecvMsg, "[Local Recv]:" + remoteIpep.Address + ":" + remoteIpep.Port + "=" + message);

            }

        }

        /// <summary>
        /// 【發送消息】
        ///  20181021
        /// </summary>
        /// <param name="obj"></param>
        private void SendMessage(object obj)
        {
            string[] data = (string[])obj;

            //字符串轉16進制
            byte[] sendBytes = HexStringToByteArray(data[0]);

            //發送到遠程IP和端口
            IPEndPoint remoteIpep = new IPEndPoint(IPAddress.Parse(data[1]), Convert.ToInt32(data[2]));

            udpcSend.Send(sendBytes, sendBytes.Length, remoteIpep);

            
            ShowMessage(tbRecvMsg, "[Local Send]:" + data[0]);
            ResetTextBox(tbSendMsg);
        }


        //構建遠程服務的收發實例
        private UdpClient remoteUdpcSend;
        private UdpClient remoteUdpcRecv;
        private Thread remoteThrRecv;

        private Thread thrSend;
        private bool isRemoteCreated = false;
        /// <summary>
        /// 【發送消息】
        ///  20181021
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnSend_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrWhiteSpace(tbRemoteIP.Text) || string.IsNullOrWhiteSpace(tbRemotePort.Text))
            {
                MessageBox.Show("遠程IP和端口不能為空！", "系統提示");
                return;
            }

            if (string.IsNullOrWhiteSpace(tbSendMsg.Text))
            {
                MessageBox.Show("發送的消息不能為空！", "系統提示");
                return;
            }

            if (!isLocalConneted)
            {
                MessageBox.Show("請先建立本地連接！", "系統提示");
                return;
            }

            
            //構建本地遠程
            if (cbIsRemoteAsLocal.Checked)//構建本地的遠程服務，本地處理
            {
                if (!isRemoteCreated)
                {
                    IPEndPoint remoteIpep = new IPEndPoint(IPAddress.Parse(tbRemoteIP.Text), Convert.ToInt32(tbRemotePort.Text));//構建遠程端口
                    remoteUdpcRecv = new UdpClient(remoteIpep);

                    //啟動遠程的監聽
                    remoteThrRecv = new Thread(RemoteRecvMessage);
                    remoteThrRecv.Start();

                    ShowMessage(tbRecvMsg, "[OS]:Remote UDP 監聽啟動完成！");
                    isRemoteCreated = true;//遠程服務已啟動
                }
                else
                {
                    //發送消息
                }

            }
            else
            {
                //發送消息,
            }

            //發送遠程，這里不做處理，直接調用udpcSend發送即可
            thrSend = new Thread(new ParameterizedThreadStart(SendMessage));

            string[] param = new string[] { tbSendMsg.Text, tbRemoteIP.Text, tbRemotePort.Text };
            thrSend.Start(param);

        }

        /// <summary>
        /// 【本地遠程發送消息】
        ///  20181021
        /// </summary>
        /// <param name="remoteIpep"></param>
        private void RemoteSendMessage(IPEndPoint remoteIpep)
        {
            remoteUdpcSend = remoteUdpcRecv;

            byte[] msg = Encoding.Default.GetBytes("遠程已收到你的消息");

            remoteUdpcSend.Send(msg, msg.Length, remoteIpep);

            ShowMessage(tbRecvMsg, "[Remote Send]:" + "遠程已收到你的消息");
        }

        /// <summary>
        /// 【本地遠程接收信息】
        ///  20181021
        /// </summary>
        private void RemoteRecvMessage()
        {
            IPEndPoint remoteIpep = new IPEndPoint(IPAddress.Any, 0);//接收任何來源的信息
            while (true)
            {
                byte[] byteRemoteRecv = remoteUdpcRecv.Receive(ref remoteIpep);
                string message = Encoding.Default.GetString(byteRemoteRecv);

                //接收到信息
                if (byteRemoteRecv.Length > 0)
                {
                    //remoteIpep.Address.ToString() 獲取發送源的IP
                    ShowMessage(tbRecvMsg, "[Remote Recv]:" + remoteIpep.Address + ":" + remoteIpep.Port + "=" + message);
                    
                    RemoteSendMessage(remoteIpep);
                }

            }
        }

        //更新顯示TextBox
        delegate void ShowMessageDelegate(TextBox tb, string msg);
        private void ShowMessage(TextBox tb, string msg)
        {
            if (tb.InvokeRequired)
            {
                ShowMessageDelegate showMessageDelegate = ShowMessage;
                tb.Invoke(showMessageDelegate, new object[] { tb, msg });
            }
            else
            {
                tb.Text += msg + "\r\n";
            }
        }

        //清空TextBox
        delegate void ResetTextBoxDelegate(TextBox tb);
        private void ResetTextBox(TextBox tb)
        {
            if (tb.InvokeRequired)
            {
                ResetTextBoxDelegate resetTextBoxDelegate = ResetTextBox;
                tb.Invoke(resetTextBoxDelegate, new object[] { tb });
            }
            else
            {
                tb.Text = "";
            }
        }

        /// <summary>
        /// 【字符串轉16進制】
        ///  20181021
        /// </summary>
        /// <param name="s"></param>
        /// <returns></returns>
        public byte[] HexStringToByteArray(string s)
        {
            if (s.Length == 0)
                throw new Exception("字符串長度為0");
            s = s.Replace(" ", "");
            byte[] buffer = new byte[s.Length / 2];
            for (int i = 0; i < s.Length; i += 2)
                buffer[i / 2] = Convert.ToByte(s.Substring(i, 2), 16);
            return buffer;
        }

        /// <summary>
        /// 【字節數組轉換成十六進制字符串(不帶空格)】
        ///  20181021
        /// </summary>
        /// <param name="data">要轉換的字節數組</param>
        /// <returns>轉換后的字符串</returns>
        public string ByteArrayToHexStringNoBlank(byte[] data)
        {
            StringBuilder sb = new StringBuilder(data.Length * 3);
            foreach (byte b in data)
                sb.Append(Convert.ToString(b, 16).PadLeft(2, '0') + " ");
            return sb.ToString().ToUpper();
        }

        /// <summary>
        /// 【窗體退出，關閉子線程】
        ///  20181021
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void FrmMain_FormClosing(object sender, FormClosingEventArgs e)
        {
            Environment.Exit(0);
        }

 


    }
}

 

 

二、界面