C#网络编程概述(3)
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最后，我就综合以上C#网络编程的一些知识，向大家展示一个很好的实例。该实例是一个运用Socket的基于同步模式的客户端应用程序，它首先通过解析服务器的IP地址建立一个终结点，同时创建一个基于流套接字的Socket连接，其运用的协议是TCP协议。通过该Socket就可以发送获取网页的命令，再通过该Socket获得服务器上默认的网页，最后通过文件流将获得的数据写入本机文件。这样就完成了网页的下载工作了，程序运行的效果如下所示：
源代码如下：（其中主要的函数为DoSocketGet（）） using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; using System.Net; using System.Net.Sockets; using System.Text; using System.IO; namespace SocketSample { /// /// Form1 的摘要说明。 /// public class Form1 : System.Windows.Forms.Form { private System.Windows.Forms.Label label1; private System.Windows.Forms.Label label2; private System.Windows.Forms.Button Download; private System.Windows.Forms.TextBox ServerAddress; private System.Windows.Forms.TextBox Filename; /// /// 必需的设计器变量。 /// private System.ComponentModel.Container components = null; public Form1() { // // Windows 窗体设计器支持所必需的 // InitializeComponent(); // // TODO: 在 InitializeComponent 调用后添加任何构造函数代码 // } /// /// 清理所有正在使用的资源。 /// protected override void Dispose( bool disposing ) { if( disposing ) { if (components != null) { components.Dispose(); } } base.Dispose( disposing ); } #region Windows Form Designer generated code /// /// 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。 /// private void InitializeComponent() { this.label1 = new System.Windows.Forms.Label(); this.label2 = new System.Windows.Forms.Label(); this.Download = new System.Windows.Forms.Button(); this.ServerAddress = new System.Windows.Forms.TextBox(); this.Filename = new System.Windows.Forms.TextBox(); this.SuspendLayout(); // // label1 // this.label1.Location = new System.Drawing.Point(16, 24); this.label1.Name = "label1"; this.label1.Size = new System.Drawing.Size(80, 23); this.label1.TabIndex = 0; this.label1.Text = "服务器地址："; this.label1.TextAlign = System.Drawing.ContentAlignment.MiddleRight; // // label2 // this.label2.Location = new System.Drawing.Point(16, 64); this.label2.Name = "label2"; this.label2.Size = new System.Drawing.Size(80, 23); this.label2.TabIndex = 1; this.label2.Text = "本地文件名："; this.label2.TextAlign = System.Drawing.ContentAlignment.MiddleRight; // // Download // this.Download.Location = new System.Drawing.Point(288, 24); this.Download.Name = "Download"; this.Download.TabIndex = 2; this.Download.Text = "开始下载"; this.Download.Click += new System.EventHandler(this.Download_Click); // // ServerAddress // this.ServerAddress.Location = new System.Drawing.Point(96, 24); this.ServerAddress.Name = "ServerAddress"; this.ServerAddress.Size = new System.Drawing.Size(176, 21); this.ServerAddress.TabIndex = 3; this.ServerAddress.Text = ""; // // Filename // this.Filename.Location = new System.Drawing.Point(96, 64); this.Filename.Name = "Filename"; this.Filename.Size = new System.Drawing.Size(176, 21); this.Filename.TabIndex = 4; this.Filename.Text = ""; // // Form1 // this.AutoScaleBaseSize = new System.Drawing.Size(6, 14); this.ClientSize = new System.Drawing.Size(376, 117); this.Controls.AddRange(new System.Windows.Forms.Control[] { this.Filename, this.ServerAddress, this.Download, this.label2, this.label1}); this.Name = "Form1"; this.Text = "网页下载器"; this.ResumeLayout(false);
#endregion /// /// 应用程序的主入口点。 /// [STAThread] static void Main() { Application.Run(new Form1()); } private string DoSocketGet(string server) { file://定义一些必要的变量以及一条要发送到服务器的字符串 Encoding ASCII = Encoding.ASCII; string Get = "GET / HTTP/1.1 Host: " + server + " Connection: Close "; Byte[] ByteGet = ASCII.GetBytes(Get); Byte[] RecvBytes = new Byte[256]; String strRetPage = null; file://获取服务器相关的IP地址列表，其中第一项即为我们所需的 IPAddress hostadd = Dns.Resolve(server).AddressList[0]; file://根据获得的服务器的IP地址创建一个终结点，端口为默认的80 IPEndPoint EPhost = new IPEndPoint(hostadd, 80); file://创建一个Socket实例 Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp );
{ file://用上面所取得的终结点连接到服务器 s.Connect(EPhost); } catch(Exception se) { MessageBox.Show("连接错误："+se.Message,"提示信息", MessageBoxButtons.RetryCancel,MessageBoxIcon.Information); }
{ strRetPage = "不能连接到服务器！"; return strRetPage; }
{ file://向服务器发送GET命令 s.Send(ByteGet, ByteGet.Length, SocketFlags.None); } catch(Exception ce) { MessageBox.Show("发送错误："+ce.Message,"提示信息", MessageBoxButtons.RetryCancel,MessageBoxIcon.Information); }
Int32 bytes = s.Receive(RecvBytes, RecvBytes.Length, 0); strRetPage = "以下是在服务器" + server + "上的默认网页： "; strRetPage = strRetPage + ASCII.GetString(RecvBytes, 0, bytes); while (bytes > 0) { bytes = s.Receive(RecvBytes, RecvBytes.Length, SocketFlags.None); strRetPage = strRetPage + ASCII.GetString(RecvBytes, 0, bytes); } file://禁用并关闭Socket实例 s.Shutdown(SocketShutdown.Both); s.Close();
return strRetPage; } private void Download_Click(object sender, System.EventArgs e) { file://将所读取的字符串转换为字节数组 byte[] content=Encoding.ASCII.GetBytes(DoSocketGet(ServerAddress.Text)); try { file://创
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