C#使用UdpClient發送和接收UDP數據示例

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
 
//本段代碼中需要新增加的命名空間
using System.Net.Sockets;
using System.Net;
using System.Threading;
 
namespace WinForm1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        /// <summary>
        /// 用於UDP發送的網絡服務類
        /// </summary>
        private UdpClient udpcSend;
        /// <summary>
        /// 用於UDP接收的網絡服務類
        /// </summary>
        private UdpClient udpcRecv;
 
        /// <summary>
        /// 按鈕：發送數據
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnSend_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrWhiteSpace(txtSendMssg.Text))
            {
                MessageBox.Show("請先輸入待發送內容");
                return;
            }
 
            // 匿名發送
            //udpcSend = new UdpClient(0);             // 自動分配本地IPv4地址
            // 實名發送
            IPEndPoint localIpep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 12345); // 本機IP，指定的端口號
            udpcSend = new UdpClient(localIpep);
            Thread thrSend = new Thread(SendMessage);
            thrSend.Start(txtSendMssg.Text);
        }
 
        /// <summary>
        /// 發送信息
        /// </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"), 8848); // 發送到的IP地址和端口號
            udpcSend.Send(sendbytes, sendbytes.Length, remoteIpep);
            udpcSend.Close();
            ResetTextBox(txtSendMssg);
        }
 
        /// <summary>
        /// 開關：在監聽UDP報文階段為true，否則為false
        /// </summary>
        bool IsUdpcRecvStart = false;
        /// <summary>
        /// 線程：不斷監聽UDP報文
        /// </summary>
        Thread thrRecv;
 
        /// <summary>
        /// 按鈕：接收數據開關
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnRecv_Click(object sender, EventArgs e)
        {
            if (!IsUdpcRecvStart) // 未監聽的情況，開始監聽
            {
                IPEndPoint localIpep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8848); // 本機IP和監聽端口號
                udpcRecv = new UdpClient(localIpep);
                thrRecv = new Thread(ReceiveMessage);
                thrRecv.Start();
                IsUdpcRecvStart = true;
                ShowMessage(txtRecvMssg, "UDP監聽器已成功啟動");
            }
            else // 正在監聽的情況，終止監聽
            {
                thrRecv.Abort(); // 必須先關閉這個線程，否則會異常
                udpcRecv.Close();
                IsUdpcRecvStart = false;
                ShowMessage(txtRecvMssg, "UDP監聽器已成功關閉");
            }
        }
 
        /// <summary>
        /// 接收數據
        /// </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));
                }
                catch (Exception ex)
                {
                    ShowMessage(txtRecvMssg, ex.Message);
                    break;
                }
            }
        }
 
        // 向RichTextBox中添加文本
        delegate void ShowMessageDelegate(RichTextBox txtbox, string message);
        private void ShowMessage(RichTextBox txtbox, string message)
        {
            if (txtbox.InvokeRequired)
            {
                ShowMessageDelegate showMessageDelegate = ShowMessage;
                txtbox.Invoke(showMessageDelegate, new object[] { txtbox, message });
            }
            else
            {
                txtbox.Text += message + "\r\n";
            }
        }
 
        // 清空指定RichTextBox中的文本
        delegate void ResetTextBoxDelegate(RichTextBox txtbox);
        private void ResetTextBox(RichTextBox txtbox)
        {
            if (txtbox.InvokeRequired)
            {
                ResetTextBoxDelegate resetTextBoxDelegate = ResetTextBox;
                txtbox.Invoke(resetTextBoxDelegate, new object[] { txtbox });
            }
            else
            {
                txtbox.Text = "";
            }
        }
 
        /// <summary>
        /// 關閉程序，強制退出
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            Environment.Exit(0);
        }
    }
}