套接字(socket)是通信的基石,是支持TCP/IP协议的网络通信的基本操作单元。它是网络通信过程中端点的抽象表示,包含进行网络通信必须的五种信息:连接使用的协议,本地主机的IP地址,本地进程的协议端口,远地主机的IP地址,远地进程的协议端口。
应用层通过传输层进行数据通信时,TCP会遇到同时为多个应用程序进程提供并发服务的问题。多个TCP连接或多个应用程序进程可能需要通过同一个 TCP协议端口传输数据。为了区别不同的应用程序进程和连接,许多计算机操作系统为应用程序与TCP/IP协议交互提供了套接字(Socket)接口。应 用层可以和传输层通过Socket接口,区分来自不同应用程序进程或网络连接的通信,实现数据传输的并发服务。
二、建立socket连接
建立Socket连接至少需要一对套接字,其中一个运行于客户端,称为ClientSocket ,另一个运行于服务器端,称为ServerSocket 。
套接字之间的连接过程分为三个步骤:服务器监听,客户端请求,连接确认。
- 服务器监听:服务器端套接字并不定位具体的客户端套接字,而是处于等待连接的状态,实时监控网络状态,等待客户端的连接请求
- 客户端请求:指客户端的套接字提出连接请求,要连接的目标是服务器端的套接字。为此,客户端的套接字必须首先描述它要连接的服务器的套接字,指出服务器端套接字的地址和端口号,然后就向服务器端套接字提出连接请求。
- 连接确认:当服务器端套接字监听到或者说接收到客户端套接字的连接请求时,就响应客户端套接字的请求,建立一个新的线程,把服务器端套接字的描述发给客户 端,一旦客户端确认了此描述,双方就正式建立连接。而服务器端套接字继续处于监听状态,继续接收其他客户端套接字的连接请求。
三、SOCKET连接与TCP连接
创建Socket连接时,可以指定使用的传输层协议,Socket可以支持不同的传输层协议(TCP或UDP),当使用TCP协议进行连接时,该Socket连接就是一个TCP连接。
四、Socket连接与HTTP连接
由于通常情况下Socket连接就是TCP连接,因此Socket连接一旦建立,通信双方即可开始相互发送数据内容,直到双方连接断开。但在实际网络应用 中,客户端到服务器之间的通信往往需要穿越多个中间节点,例如路由器、网关、防火墙等,大部分防火墙默认会关闭长时间处于非活跃状态的连接而导致 Socket 连接断连,因此需要通过轮询告诉网络,该连接处于活跃状态。
而HTTP连接使用的是“请求—响应”的方式,不仅在请求时需要先建立连接,而且需要客户端向服务器发出请求后,服务器端才能回复数据。
很多情况下,需要服务器端主动向客户端推送数据,保持客户端与服务器数据的实时与同步。此时若双方建立的是Socket连接,服务器就可以直接将数据传送 给客户端;若双方建立的是HTTP连接,则服务器需要等到客户端发送一次请求后才能将数据传回给客户端,因此,客户端定时向服务器端发送连接请求,不仅可 以保持在线,同时也是在“询问”服务器是否有新的数据,如果有就将数据传给客户端。
五、Socket服务端与客户端通信示意图
六、服务端与客户端代码
1、服务端
(1)服务端窗口设计
namespace SocketForm { partial class Form1 { /// <summary> /// 必需的设计器变量。 /// </summary> private System.ComponentModel.IContainer components = null; /// <summary> /// 清理所有正在使用的资源。 /// </summary> /// <param name="disposing">如果应释放托管资源,为 true;否则为 false。</param> protected override void Dispose(bool disposing) { if (disposing && (components != null)) { components.Dispose(); } base.Dispose(disposing); } #region Windows 窗体设计器生成的代码 /// <summary> /// 设计器支持所需的方法 - 不要 /// 使用代码编辑器修改此方法的内容。 /// </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 = "开始监听"; 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 = "发送"; 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)服务端逻辑设计
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 { //点击开始监听时 在服务端创建一个负责监听IP和端口号的Socket Socket socketWatch = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); IPAddress ip = IPAddress.Any; //创建对象端口 IPEndPoint point = new IPEndPoint(ip, Convert.ToInt32(tb_port.Text)); socketWatch.Bind(point);//绑定端口号 ShowMsg("监听成功!"); socketWatch.Listen(10);//设置监听 //创建监听线程 Thread thread = new Thread(Listen); thread.IsBackground = true; thread.Start(socketWatch); } catch { } } /// <summary> /// 等待客户端的连接 并且创建与之通信的Socket /// </summary> Socket socketSend; void Listen(object o) { try { Socket socketWatch = o as Socket; while (true) { socketSend = socketWatch.Accept();//等待接收客户端连接 ShowMsg(socketSend.RemoteEndPoint.ToString() + ":" + "连接成功!"); //开启一个新线程,执行接收消息方法 Thread r_thread = new Thread(Received); r_thread.IsBackground = true; r_thread.Start(socketSend); } } catch { } } /// <summary> /// 服务器端不停的接收客户端发来的消息 /// </summary> /// <param name="o"></param> void Received(object o) { try { Socket socketSend = o as Socket; while (true) { //客户端连接服务器成功后,服务器接收客户端发送的消息 byte[] buffer = new byte[1024 * 1024 * 3]; //实际接收到的有效字节数 int len = socketSend.Receive(buffer); if (len == 0) { break; } string str = Encoding.UTF8.GetString(buffer, 0, len); ShowMsg(socketSend.RemoteEndPoint + ":" + str); } } catch { } } /// <summary> /// 服务器向客户端发送消息 /// </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 + " "); } 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、客户端
(1)客户端窗口设计
namespace SocketClient { partial class Form1 { /// <summary> /// 必需的设计器变量。 /// </summary> private System.ComponentModel.IContainer components = null; /// <summary> /// 清理所有正在使用的资源。 /// </summary> /// <param name="disposing">如果应释放托管资源,为 true;否则为 false。</param> protected override void Dispose(bool disposing) { if (disposing && (components != null)) { components.Dispose(); } base.Dispose(disposing); } #region Windows 窗体设计器生成的代码 /// <summary> /// 设计器支持所需的方法 - 不要 /// 使用代码编辑器修改此方法的内容。 /// </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 = "连接"; 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 = "发送"; 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)客户端逻辑设计
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 { //创建客户端Socket,获得远程ip和端口号 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("连接成功!"); //开启新的线程,不停的接收服务器发来的消息 Thread c_thread = new Thread(Received); c_thread.IsBackground = true; c_thread.Start(); } catch (Exception){ ShowMsg("IP或者端口号错误..."); } } void ShowMsg(string str) { textBox1.AppendText(str + " "); } /// <summary> /// 接收服务端返回的消息 /// </summary> void Received() { while (true) { try { byte[] buffer = new byte[1024 * 1024 * 3]; //实际接收到的有效字节数 int len = socketSend.Receive(buffer); if (len == 0) { break; } string str = Encoding.UTF8.GetString(buffer, 0, len); ShowMsg(socketSend.RemoteEndPoint + ":" + str); } catch { } } } /// <summary> /// 向服务器发送消息 /// </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; } } }
1、服务端
2、客户端