C#中Socket的简单使用

以前学过的Socket,后来没怎么用过,就基本忘了,所以闲来时重新回顾学习一番.

一.Socket的概念

Socket其实并不是一个协议,而是为了方便使用TCP或UDP而抽象出来的一层,是位于应用层和传输控制层之间的一组接口.

当两台主机通信是,必须通过Socket连接,Socket则利用TCP/IP协议建立TCP连接.TCP连接则更依赖于底层的IP协议.Socket是控制层传输协议.

双向的通信连接实现数据的交换,连接的一端成为一个Socket.

二.网络通信三要素

• IP地址(网络上主机设备的唯一标识)
• 端口号(定位程序)
•      有效端口:0~65535,其中0~1024由系统使用,开发中一般使用1024以上端口.
• 传输协议(用什么样的方式进行交互)
•      常见协议:TCP(面向连接,提供可靠的服务),UDP(无连接,传输速度快)

三.Socket的通信流程

四.C#中Socket的简单使用步骤

第一步:服务端监听某个端口

第二步:客户端向服务端地址和端口发起Socket请求

第三步:服务器接收连接请求后创建Socket连接,并维护这个连接队列

第四步:客户端和服务端就建立起了双工同信,客户端与服务端就可以实现彼此发送消息

五.简单代码实例

1.服务端代码

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

namespace SocketUtil
{
    public class SocketServer
    {
        private string _ip = string.Empty;
        private int _port = 0;
        private Socket _socket = null;
        private byte[] buffer = new byte[1024 * 1024 * 2];
        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="ip">监听的IP</param>
        /// <param name="port">监听的端口</param>
        public SocketServer(string ip, int port)
        {
            this._ip = ip;
            this._port = port;
        }
        public SocketServer(int port)
        {
            this._ip = "0.0.0.0";
            this._port = port;
        }

        public void StartListen()
        {
            try
            {
                //1.0 实例化套接字(IP4寻找协议,流式协议,TCP协议)
                _socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                //2.0 创建IP对象
                IPAddress address = IPAddress.Parse(_ip);
                //3.0 创建网络端口,包括ip和端口
                IPEndPoint endPoint = new IPEndPoint(address, _port);
                //4.0 绑定套接字
                _socket.Bind(endPoint);
                //5.0 设置最大连接数
                _socket.Listen(int.MaxValue);
                Console.WriteLine("监听{0}消息成功", _socket.LocalEndPoint.ToString());
                //6.0 开始监听
                Thread thread = new Thread(ListenClientConnect);
                thread.Start();

            }
            catch (Exception ex)
            {
            }
        }
        /// <summary>
        /// 监听客户端连接
        /// </summary>
        private void ListenClientConnect()
        {
            try
            {
                while (true)
                {
                    //Socket创建的新连接
                    Socket clientSocket = _socket.Accept();
                    clientSocket.Send(Encoding.UTF8.GetBytes("服务端发送消息:"));
                    Thread thread = new Thread(ReceiveMessage);
                    thread.Start(clientSocket);
                }
            }
            catch (Exception)
            {
            }
        }

        /// <summary>
        /// 接收客户端消息
        /// </summary>
        /// <param name="socket">来自客户端的socket</param>
        private void ReceiveMessage(object socket)
        {
            Socket clientSocket = (Socket)socket;
            while (true)
            {
                try
                {
                    //获取从客户端发来的数据
                    int length = clientSocket.Receive(buffer);
                    Console.WriteLine("接收客户端{0},消息{1}", clientSocket.RemoteEndPoint.ToString(), Encoding.UTF8.GetString(buffer, 0, length));
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.Message);
                    clientSocket.Shutdown(SocketShutdown.Both);
                    clientSocket.Close();
                    break;
                }
            }
        }
    }
}

2.客户端代码

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

namespace SocketUtil
{
    public class SocketClient
    {
        private string _ip = string.Empty;
        private int _port = 0;
        private Socket _socket = null;
        private byte[] buffer = new byte[1024 * 1024 * 2];

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="ip">连接服务器的IP</param>
        /// <param name="port">连接服务器的端口</param>
        public SocketClient(string ip, int port)
        {
            this._ip = ip;
            this._port = port;
        }
        public SocketClient(int port)
        {
            this._ip = "127.0.0.1";
            this._port = port;
        }

        /// <summary>
        /// 开启服务,连接服务端
        /// </summary>
        public void StartClient()
        {
            try
            {
                //1.0 实例化套接字(IP4寻址地址,流式传输,TCP协议)
                _socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                //2.0 创建IP对象
                IPAddress address = IPAddress.Parse(_ip);
                //3.0 创建网络端口包括ip和端口
                IPEndPoint endPoint = new IPEndPoint(address, _port);
                //4.0 建立连接
                _socket.Connect(endPoint);
                Console.WriteLine("连接服务器成功");
                //5.0 接收数据
                int length = _socket.Receive(buffer);
                Console.WriteLine("接收服务器{0},消息:{1}", _socket.RemoteEndPoint.ToString(), Encoding.UTF8.GetString(buffer,0,length));
                //6.0 像服务器发送消息
                for (int i = 0; i < 10; i++)
                {
                    Thread.Sleep(2000);
                    string sendMessage = string.Format("客户端发送的消息,当前时间{0}", DateTime.Now.ToString());
                    _socket.Send(Encoding.UTF8.GetBytes(sendMessage));
                    Console.WriteLine("像服务发送的消息:{0}", sendMessage);
                }
            }
            catch (Exception ex)
            {
                _socket.Shutdown(SocketShutdown.Both);
                _socket.Close();
                Console.WriteLine(ex.Message);
            }
            Console.WriteLine("发送消息结束");
            Console.ReadKey();
        }
    }
}

3.分别开启客户端和服务端

using SocketUtil;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SocketClientApp
{
    class Program
    {
        static void Main(string[] args)
        {
            SocketClient client = new SocketClient(8888);
            client.StartClient();
            Console.ReadKey();
        }
    }
}

using SocketUtil;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SocketServerApp
{
    class Program
    {
        static void Main(string[] args)
        {
            SocketServer server = new SocketServer(8888);
            server.StartListen();
            Console.ReadKey();
        }
    }
}

4. 运行效果图