C# socket编程第二篇

     既然有了方向，确定了方案就要一步一步的执行方案。socket+udp通信要考虑的问题很多，比如大文件传输的时候如何分包，如何校验，如何判断是否丢包，丢包后从发，如何保证文件的完整性等等一系列问题。

      在考虑这些问题的最开始，我们要解决的实现SOCKET通信，如果通信都不能实现，又谈何程序的完整性。这贴一个socket+Udp的demo。新建两个控制台应用程序，一个是服务端，一个是客户端。模拟客服端和服务端通信

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace Bose.XueLeCN.COM.FileReceiveControl
{
    class Program
    {
        static void Main(string[] args)
        {
            int recv;
            byte[] data = new byte[1024];

            //构建TCP 服务器

            //得到本机IP，设置TCP端口号         
            IPEndPoint ipep = new IPEndPoint(IPAddress.Any, 8001);
            Socket newsock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

            //绑定网络地址
            newsock.Bind(ipep);

            Console.WriteLine("This is a Server, host name is {0}", Dns.GetHostName());

            //等待客户机连接
            Console.WriteLine("Waiting for a client");

            //得到客户机IP
            IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);
            EndPoint Remote = (EndPoint)(sender);
            recv = newsock.ReceiveFrom(data, ref Remote);
            Console.WriteLine("Message received from {0}: ", Remote.ToString());
            Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv));

            //客户机连接成功后，发送欢迎信息
            string welcome = "Welcome ! ";

            //字符串与字节数组相互转换
            data = Encoding.ASCII.GetBytes(welcome);

            //发送信息
            newsock.SendTo(data, data.Length, SocketFlags.None, Remote);
            while (true)
            {
                data = new byte[1024];
                //发送接受信息
                recv = newsock.ReceiveFrom(data, ref Remote);
                Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv));
                newsock.SendTo(data, recv, SocketFlags.None, Remote);
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace FileDistributeControl
{
    class Program
    {
        static void Main(string[] args)
        {
            byte[] data = new byte[1024];
            string input, stringData;

            //构建TCP 服务器

            Console.WriteLine("This is a Client, host name is {0}", Dns.GetHostName());

            //设置服务IP，设置TCP端口号
            IPEndPoint ipep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8001);

            //定义网络类型，数据连接类型和网络协议UDP
            Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

            string welcome = "Hello! ";
            data = Encoding.ASCII.GetBytes(welcome);
            server.SendTo(data, data.Length, SocketFlags.None, ipep);
            IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);
            EndPoint Remote = (EndPoint)sender;

            data = new byte[1024];
            //对于不存在的IP地址，加入此行代码后，可以在指定时间内解除阻塞模式限制
            //server.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 100);
            int recv = server.ReceiveFrom(data, ref Remote);
            Console.WriteLine("Message received from {0}: ", Remote.ToString());
            Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv));
            while (true)
            {
                input = Console.ReadLine();
                if (input == "exit")
                    break;
                server.SendTo(Encoding.ASCII.GetBytes(input), Remote);
                data = new byte[1024];
                recv = server.ReceiveFrom(data, ref Remote);
                stringData = Encoding.ASCII.GetString(data, 0, recv);
                Console.WriteLine(stringData);
            }
            Console.WriteLine("Stopping Client.");
            server.Close();       
        }
    }
}

先运行服务端，再运行客户端，否则会报错。通信实现了，下面我们要做的就是在这基础上完善我们的程序，我们的最终目的是用socket来传输文件。