C# Socket編程筆記(4)

UDPServer

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Net.Sockets;
namespace SimpleUdpSrvr
{
    class Program
    {
        static void Main(string[] args)
        {
            int recv;
            byte[] data = new byte[1024];
            IPEndPoint ipep = new IPEndPoint(IPAddress.Any, 9050);//定義一網絡端點
            Socket newsock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);//定義一個Socket
            newsock.Bind(ipep);//Socket與本地的一個終結點相關聯
            Console.WriteLine("Waiting for a clIEnt..");
            IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);//定義要發送的計算機的地址
            EndPoint Remote = (EndPoint)(sender);//
            recv = newsock.ReceiveFrom(data, ref Remote);//接受數據           
            Console.WriteLine("Message received from{0}:", Remote.ToString());
            Console.WriteLine(Encoding.ASCII.GetBytes(data,0,recv));
            string welcome = "Welcome to my test server!";
            data = Encoding.ASCII.GetBytes(welcome);
            newsock.SendTo(data, data.Length, SocketFlags.None, Remote);
            while (true)
            {
                data = new byte[1024];
                recv = newsock.ReceiveFrom(data, ref Remote);
                Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv));
                newsock.SendTo(data, recv, SocketFlags.None, Remote);
            }
        }
    }
}

UDPClIEnt

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Net.Sockets;
namespace SimpleUdpClIEnt
{
    class Program
    {
        static void Main(string[] args)
        {
            byte[] data = new byte[1024];//定義一個數組用來做數據的緩沖區
            string input, stringData;
            IPEndPoint ipep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 9050);
            Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
            string welcome = "Hello,are you there?";
            data = Encoding.ASCII.GetBytes(welcome);
            server.SendTo(data, data.Length, SocketFlags.None, ipep);//將數據發送到指定的終結點
            IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);
            EndPoint Remote = (EndPoint)sender;
            data = new byte[1024];
            int recv = server.ReceiveFrom(data, ref Remote);//接受來自服務器的數據
            Console.WriteLine("Message received from{0}:", Remote.ToString());
            Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv));
            while (true)//讀取數據
            {
                input = Console.ReadLine();//從鍵盤讀取數據
                if (input == "text")//結束標記
                {
                    break;
                }
                server.SendTo(Encoding.ASCII.GetBytes(input), Remote);//將數據發送到指定的終結點Remote
                data = new byte[1024];
                recv = server.ReceiveFrom(data, ref Remote);//從Remote接受數據
                stringData = Encoding.ASCII.GetString(data, 0, recv);
                Console.WriteLine(stringData);
            }
            Console.WriteLine("Stopping clIEnt");
            server.Close();
        }
    }
}

上面的示例只是簡單的應用了socket來實現通信，你也可以實現異步socket、IP組播 等等。

MS還為我們提供了幾個助手類：TcpClient類、TcpListener類、UDPClIEnt類。這幾個類簡化了一些操作，所以你也可以利用這幾類來寫上面的代碼，但我個人還是比較習慣直接用socket來寫。

既然快寫完了，那我就再多啰嗦幾句。在需要即時響應的軟件中，我個人更傾向使用UDP來實現通信，因為相比TCP來說，UDP占用更少的資源，且響應速度快，延時低。至於UDP的可靠性，則可以通過在應用層加以控制來滿足。當然如果可靠性要求高的環境下，還是建議使用TCP。