Socket通信實例（C#）

SOCKET原理

一、套接字（socket）概念

　　套接字（socket）是通信的基石，是支持TCP/IP協議的網絡通信的基本操作單元。它是網絡通信過程中端點的抽象表示，包含進行網絡通信必須的五種信息：連接使用的協議，本地主機的IP地址，本地進程的協議端口，遠地主機的IP地址，遠地進程的協議端口。

　　應用層通過傳輸層進行數據通信時，TCP會遇到同時為多個應用程序進程提供並發服務的問題。多個TCP連接或多個應用程序進程可能需要通過同一個 TCP協議端口傳輸數據。為了區別不同的應用程序進程和連接，許多計算機操作系統為應用程序與TCP／IP協議交互提供了套接字(Socket)接口。應 用層可以和傳輸層通過Socket接口，區分來自不同應用程序進程或網絡連接的通信，實現數據傳輸的並發服務。

二、建立socket連接

　　建立Socket連接至少需要一對套接字，其中一個運行於客戶端，稱為ClientSocket ，另一個運行於服務器端，稱為ServerSocket 。

　　套接字之間的連接過程分為三個步驟：服務器監聽，客戶端請求，連接確認。

1. 服務器監聽：服務器端套接字並不定位具體的客戶端套接字，而是處於等待連接的狀態，實時監控網絡狀態，等待客戶端的連接請求 
2. 客戶端請求：指客戶端的套接字提出連接請求，要連接的目標是服務器端的套接字。為此，客戶端的套接字必須首先描述它要連接的服務器的套接字，指出服務器端套接字的地址和端口號，然后就向服務器端套接字提出連接請求。
3. 連接確認：當服務器端套接字監聽到或者說接收到客戶端套接字的連接請求時，就響應客戶端套接字的請求，建立一個新的線程，把服務器端套接字的描述發給客戶 端，一旦客戶端確認了此描述，雙方就正式建立連接。而服務器端套接字繼續處於監聽狀態，繼續接收其他客戶端套接字的連接請求。

三、SOCKET連接與TCP連接

　　創建Socket連接時，可以指定使用的傳輸層協議，Socket可以支持不同的傳輸層協議（TCP或UDP），當使用TCP協議進行連接時，該Socket連接就是一個TCP連接。

四、Socket連接與HTTP連接 

　　由於通常情況下Socket連接就是TCP連接，因此Socket連接一旦建立，通信雙方即可開始相互發送數據內容，直到雙方連接斷開。但在實際網絡應用 中，客戶端到服務器之間的通信往往需要穿越多個中間節點，例如路由器、網關、防火牆等，大部分防火牆默認會關閉長時間處於非活躍狀態的連接而導致 Socket 連接斷連，因此需要通過輪詢告訴網絡，該連接處於活躍狀態。

　　而HTTP連接使用的是“請求—響應”的方式，不僅在請求時需要先建立連接，而且需要客戶端向服務器發出請求后，服務器端才能回復數據。

　　很多情況下，需要服務器端主動向客戶端推送數據，保持客戶端與服務器數據的實時與同步。此時若雙方建立的是Socket連接，服務器就可以直接將數據傳送 給客戶端；若雙方建立的是HTTP連接，則服務器需要等到客戶端發送一次請求后才能將數據傳回給客戶端，因此，客戶端定時向服務器端發送連接請求，不僅可 以保持在線，同時也是在“詢問”服務器是否有新的數據，如果有就將數據傳給客戶端。

五、Socket服務端與客戶端通信示意圖

六、服務端與客戶端代碼

　　1、服務端

　　（1）服務端窗口設計

namespace SocketForm
{
    partial class Form1
    {
        /// <summary>
        /// 必需的設計器變量。
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// 清理所有正在使用的資源。
        /// </summary>
        /// <param name="disposing">如果應釋放托管資源，為 true；否則為 false。</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows 窗體設計器生成的代碼

        /// <summary>
        /// 設計器支持所需的方法 - 不要
        /// 使用代碼編輯器修改此方法的內容。
        /// </summary>
        private void InitializeComponent()
        {
            this.panel1 = new System.Windows.Forms.Panel();
            this.tb_ip = new System.Windows.Forms.TextBox();
            this.lb_Ip = new System.Windows.Forms.Label();
            this.lb_port = new System.Windows.Forms.Label();
            this.tb_port = new System.Windows.Forms.TextBox();
            this.bt_connnect = new System.Windows.Forms.Button();
            this.listBox1 = new System.Windows.Forms.ListBox();
            this.txt_msg = new System.Windows.Forms.TextBox();
            this.bt_send = new System.Windows.Forms.Button();
            this.panel1.SuspendLayout();
            this.SuspendLayout();
            // 
            // panel1
            // 
            this.panel1.Controls.Add(this.bt_connnect);
            this.panel1.Controls.Add(this.lb_port);
            this.panel1.Controls.Add(this.tb_port);
            this.panel1.Controls.Add(this.lb_Ip);
            this.panel1.Controls.Add(this.tb_ip);
            this.panel1.Location = new System.Drawing.Point(21, 12);
            this.panel1.Name = "panel1";
            this.panel1.Size = new System.Drawing.Size(580, 70);
            this.panel1.TabIndex = 0;
            // 
            // tb_ip
            // 
            this.tb_ip.Location = new System.Drawing.Point(44, 18);
            this.tb_ip.Name = "tb_ip";
            this.tb_ip.Size = new System.Drawing.Size(100, 21);
            this.tb_ip.TabIndex = 0;
            this.tb_ip.Text = "127.0.0.1";
            // 
            // lb_Ip
            // 
            this.lb_Ip.AutoSize = true;
            this.lb_Ip.Location = new System.Drawing.Point(15, 21);
            this.lb_Ip.Name = "lb_Ip";
            this.lb_Ip.Size = new System.Drawing.Size(23, 12);
            this.lb_Ip.TabIndex = 1;
            this.lb_Ip.Text = "IP:";
            // 
            // lb_port
            // 
            this.lb_port.AutoSize = true;
            this.lb_port.Location = new System.Drawing.Point(158, 24);
            this.lb_port.Name = "lb_port";
            this.lb_port.Size = new System.Drawing.Size(35, 12);
            this.lb_port.TabIndex = 3;
            this.lb_port.Text = "Port:";
            // 
            // tb_port
            // 
            this.tb_port.Location = new System.Drawing.Point(199, 21);
            this.tb_port.Name = "tb_port";
            this.tb_port.Size = new System.Drawing.Size(100, 21);
            this.tb_port.TabIndex = 2;
            this.tb_port.Text = "80";
            // 
            // bt_connnect
            // 
            this.bt_connnect.Location = new System.Drawing.Point(316, 15);
            this.bt_connnect.Name = "bt_connnect";
            this.bt_connnect.Size = new System.Drawing.Size(132, 42);
            this.bt_connnect.TabIndex = 4;
            this.bt_connnect.Text = "開始監聽";
            this.bt_connnect.UseVisualStyleBackColor = true;
            this.bt_connnect.Click += new System.EventHandler(this.bt_connnect_Click);
            // 
            // listBox1
            // 
            this.listBox1.FormattingEnabled = true;
            this.listBox1.ItemHeight = 12;
            this.listBox1.Location = new System.Drawing.Point(21, 112);
            this.listBox1.Name = "listBox1";
            this.listBox1.Size = new System.Drawing.Size(580, 124);
            this.listBox1.TabIndex = 1;
            // 
            // txt_msg
            // 
            this.txt_msg.Location = new System.Drawing.Point(21, 255);
            this.txt_msg.Multiline = true;
            this.txt_msg.Name = "txt_msg";
            this.txt_msg.Size = new System.Drawing.Size(424, 73);
            this.txt_msg.TabIndex = 2;
            // 
            // bt_send
            // 
            this.bt_send.Location = new System.Drawing.Point(471, 266);
            this.bt_send.Name = "bt_send";
            this.bt_send.Size = new System.Drawing.Size(119, 52);
            this.bt_send.TabIndex = 3;
            this.bt_send.Text = "發送";
            this.bt_send.UseVisualStyleBackColor = true;
            this.bt_send.Click += new System.EventHandler(this.bt_send_Click);
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(695, 340);
            this.Controls.Add(this.bt_send);
            this.Controls.Add(this.txt_msg);
            this.Controls.Add(this.listBox1);
            this.Controls.Add(this.panel1);
            this.Name = "Form1";
            this.Text = "SocketForm";
            this.Load += new System.EventHandler(this.Form1_Load);
            this.panel1.ResumeLayout(false);
            this.panel1.PerformLayout();
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.Panel panel1;
        private System.Windows.Forms.Button bt_connnect;
        private System.Windows.Forms.Label lb_port;
        private System.Windows.Forms.TextBox tb_port;
        private System.Windows.Forms.Label lb_Ip;
        private System.Windows.Forms.TextBox tb_ip;
        private System.Windows.Forms.ListBox listBox1;
        private System.Windows.Forms.TextBox txt_msg;
        private System.Windows.Forms.Button bt_send;
    }
}

　　（2）服務端邏輯設計

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.Windows.Forms;

namespace SocketForm
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void bt_connnect_Click(object sender, EventArgs e)
        {

            try
            {
                //點擊開始監聽時 在服務端創建一個負責監聽IP和端口號的Socket
                Socket socketWatch = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                IPAddress ip = IPAddress.Any;
                //創建對象端口
                IPEndPoint point = new IPEndPoint(ip, Convert.ToInt32(tb_port.Text));

                socketWatch.Bind(point);//綁定端口號
                ShowMsg("監聽成功!");
                socketWatch.Listen(10);//設置監聽

                //創建監聽線程
                Thread thread = new Thread(Listen);
                thread.IsBackground = true;
                thread.Start(socketWatch);
            }
            catch { }
           
        }
       
        /// <summary>
        /// 等待客戶端的連接 並且創建與之通信的Socket
        /// </summary>
        Socket socketSend;
        void Listen(object o)
        {
            try
            {
                Socket socketWatch = o as Socket;
                while (true)
                {
                    socketSend = socketWatch.Accept();//等待接收客戶端連接
                    ShowMsg(socketSend.RemoteEndPoint.ToString() + ":" + "連接成功!");
                    //開啟一個新線程，執行接收消息方法
                    Thread r_thread = new Thread(Received);
                    r_thread.IsBackground = true;
                    r_thread.Start(socketSend);
                }
            }
            catch { }
        }
        /// <summary>
        /// 服務器端不停的接收客戶端發來的消息
        /// </summary>
        /// <param name="o"></param>
        void Received(object o)
        {
            try
            {
                Socket socketSend = o as Socket;
                while (true)
                {
                    //客戶端連接服務器成功后，服務器接收客戶端發送的消息
                    byte[] buffer = new byte[1024 * 1024 * 3];
                    //實際接收到的有效字節數
                    int len = socketSend.Receive(buffer);
                    if (len == 0)
                    {
                        break;
                    }
                    string str = Encoding.UTF8.GetString(buffer, 0, len);
                    ShowMsg(socketSend.RemoteEndPoint + ":" + str);
                }
            }
            catch { }
        }
        /// <summary>
        /// 服務器向客戶端發送消息
        /// </summary>
        /// <param name="str"></param>
        void Send(string str) {
            byte[] buffer = Encoding.UTF8.GetBytes(str);
            socketSend.Send(buffer);
        }

        void ShowMsg(string msg)
        {
            listBox1.Items.Add(msg + "\r\n");
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Control.CheckForIllegalCrossThreadCalls = false;
        }

        private void bt_send_Click(object sender, EventArgs e)
        {
            Send(txt_msg.Text.Trim());
        }
    }
}

　　2、客戶端

　　（1）客戶端窗口設計

namespace SocketClient
{
    partial class Form1
    {
        /// <summary>
        /// 必需的設計器變量。
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// 清理所有正在使用的資源。
        /// </summary>
        /// <param name="disposing">如果應釋放托管資源，為 true；否則為 false。</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows 窗體設計器生成的代碼

        /// <summary>
        /// 設計器支持所需的方法 - 不要
        /// 使用代碼編輯器修改此方法的內容。
        /// </summary>
        private void InitializeComponent()
        {
            this.panel1 = new System.Windows.Forms.Panel();
            this.lb_ip = new System.Windows.Forms.Label();
            this.txt_ip = new System.Windows.Forms.TextBox();
            this.txt_port = new System.Windows.Forms.TextBox();
            this.lb_port = new System.Windows.Forms.Label();
            this.bt_connect = new System.Windows.Forms.Button();
            this.textBox1 = new System.Windows.Forms.TextBox();
            this.txt_msg = new System.Windows.Forms.TextBox();
            this.bt_send = new System.Windows.Forms.Button();
            this.panel1.SuspendLayout();
            this.SuspendLayout();
            // 
            // panel1
            // 
            this.panel1.Controls.Add(this.bt_connect);
            this.panel1.Controls.Add(this.txt_port);
            this.panel1.Controls.Add(this.lb_port);
            this.panel1.Controls.Add(this.txt_ip);
            this.panel1.Controls.Add(this.lb_ip);
            this.panel1.Location = new System.Drawing.Point(12, 12);
            this.panel1.Name = "panel1";
            this.panel1.Size = new System.Drawing.Size(463, 75);
            this.panel1.TabIndex = 0;
            // 
            // lb_ip
            // 
            this.lb_ip.AutoSize = true;
            this.lb_ip.Location = new System.Drawing.Point(14, 23);
            this.lb_ip.Name = "lb_ip";
            this.lb_ip.Size = new System.Drawing.Size(23, 12);
            this.lb_ip.TabIndex = 0;
            this.lb_ip.Text = "IP:";
            // 
            // txt_ip
            // 
            this.txt_ip.Location = new System.Drawing.Point(43, 20);
            this.txt_ip.Name = "txt_ip";
            this.txt_ip.Size = new System.Drawing.Size(100, 21);
            this.txt_ip.TabIndex = 1;
            this.txt_ip.Text = "127.0.0.1";
            // 
            // txt_port
            // 
            this.txt_port.Location = new System.Drawing.Point(207, 23);
            this.txt_port.Name = "txt_port";
            this.txt_port.Size = new System.Drawing.Size(100, 21);
            this.txt_port.TabIndex = 3;
            this.txt_port.Text = "2001";
            // 
            // lb_port
            // 
            this.lb_port.AutoSize = true;
            this.lb_port.Location = new System.Drawing.Point(166, 29);
            this.lb_port.Name = "lb_port";
            this.lb_port.Size = new System.Drawing.Size(35, 12);
            this.lb_port.TabIndex = 2;
            this.lb_port.Text = "port:";
            // 
            // bt_connect
            // 
            this.bt_connect.Location = new System.Drawing.Point(313, 9);
            this.bt_connect.Name = "bt_connect";
            this.bt_connect.Size = new System.Drawing.Size(113, 47);
            this.bt_connect.TabIndex = 4;
            this.bt_connect.Text = "連接";
            this.bt_connect.UseVisualStyleBackColor = true;
            this.bt_connect.Click += new System.EventHandler(this.bt_connect_Click);
            // 
            // textBox1
            // 
            this.textBox1.Location = new System.Drawing.Point(12, 103);
            this.textBox1.Multiline = true;
            this.textBox1.Name = "textBox1";
            this.textBox1.Size = new System.Drawing.Size(463, 114);
            this.textBox1.TabIndex = 1;
            // 
            // txt_msg
            // 
            this.txt_msg.Location = new System.Drawing.Point(12, 246);
            this.txt_msg.Multiline = true;
            this.txt_msg.Name = "txt_msg";
            this.txt_msg.Size = new System.Drawing.Size(291, 54);
            this.txt_msg.TabIndex = 2;
            // 
            // bt_send
            // 
            this.bt_send.Location = new System.Drawing.Point(325, 246);
            this.bt_send.Name = "bt_send";
            this.bt_send.Size = new System.Drawing.Size(113, 54);
            this.bt_send.TabIndex = 3;
            this.bt_send.Text = "發送";
            this.bt_send.UseVisualStyleBackColor = true;
            this.bt_send.Click += new System.EventHandler(this.bt_send_Click);
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(493, 323);
            this.Controls.Add(this.bt_send);
            this.Controls.Add(this.txt_msg);
            this.Controls.Add(this.textBox1);
            this.Controls.Add(this.panel1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.Load += new System.EventHandler(this.Form1_Load);
            this.panel1.ResumeLayout(false);
            this.panel1.PerformLayout();
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.Panel panel1;
        private System.Windows.Forms.Label lb_ip;
        private System.Windows.Forms.Button bt_connect;
        private System.Windows.Forms.TextBox txt_port;
        private System.Windows.Forms.Label lb_port;
        private System.Windows.Forms.TextBox txt_ip;
        private System.Windows.Forms.TextBox textBox1;
        private System.Windows.Forms.TextBox txt_msg;
        private System.Windows.Forms.Button bt_send;
    }
}

　　（2）客戶端邏輯設計

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.Windows.Forms;

namespace SocketClient
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        Socket socketSend;
        private void bt_connect_Click(object sender, EventArgs e)
        {
            try
            {
                //創建客戶端Socket，獲得遠程ip和端口號
                socketSend = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                IPAddress ip = IPAddress.Parse(txt_ip.Text);
                IPEndPoint point = new IPEndPoint(ip, Convert.ToInt32(txt_port.Text));

                socketSend.Connect(point);
                ShowMsg("連接成功!");
                //開啟新的線程，不停的接收服務器發來的消息
                Thread c_thread = new Thread(Received);
                c_thread.IsBackground = true;
                c_thread.Start();
            }
            catch (Exception){
                ShowMsg("IP或者端口號錯誤...");
            }
 
        }
        void ShowMsg(string str)
        {
            textBox1.AppendText(str + "\r\n");
        }
        /// <summary>
        /// 接收服務端返回的消息
        /// </summary>
        void Received()
        {
            while (true)
            {
                try
                {
                    byte[] buffer = new byte[1024 * 1024 * 3];
                    //實際接收到的有效字節數
                    int len = socketSend.Receive(buffer);
                    if (len == 0)
                    {
                        break;
                    }
                    string str = Encoding.UTF8.GetString(buffer, 0, len);
                    ShowMsg(socketSend.RemoteEndPoint + ":" + str);
                }
                catch { }
            }
        } 
        /// <summary>
        /// 向服務器發送消息
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void bt_send_Click(object sender, EventArgs e)
        {
            try
            {
                string msg = txt_msg.Text.Trim();
                byte[] buffer = new byte[1024 * 1024 * 3];
                buffer = Encoding.UTF8.GetBytes(msg);
                socketSend.Send(buffer);
            }
            catch { }
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Control.CheckForIllegalCrossThreadCalls = false;
        }
    }
}

七、運行效果

　　1、服務端

　　2、客戶端