用Visual C#实现文件下载

using System;

using System.Drawing;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

using System.Net;

using System.IO;

using System.Threading;

namespace MyGetCar

{

///

/// 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.TextBox srcAddress;

private System.Windows.Forms.TextBox tarAddress;

private System.Windows.Forms.StatusBar statusBar;

private System.Windows.Forms.Button Start;

private WebClient client = new WebClient();

///

/// 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.srcAddress = new System.Windows.Forms.TextBox();

this.tarAddress = new System.Windows.Forms.TextBox();

this.statusBar = new System.Windows.Forms.StatusBar();

this.Start = new System.Windows.Forms.Button();

this.button1 = new System.Windows.Forms.Button();

this.SuspendLayout();

//

// label1

//

this.label1.Location = new System.Drawing.Point(8, 32);

this.label1.Name = "label1";

this.label1.Size = new System.Drawing.Size(72, 23);

this.label1.TabIndex = 0;

this.label1.Text = "文件地址：";

this.label1.TextAlign = System.Drawing.ContentAlignment.MiddleRight;

//

// label2

//

this.label2.Location = new System.Drawing.Point(8, 72);

this.label2.Name = "label2";

this.label2.Size = new System.Drawing.Size(72, 23);

this.label2.TabIndex = 1;

this.label2.Text = "另存到：";

this.label2.TextAlign = System.Drawing.ContentAlignment.MiddleRight;

//

// srcAddress

//

this.srcAddress.Location = new System.Drawing.Point(80, 32);

this.srcAddress.Name = "srcAddress";

this.srcAddress.Size = new System.Drawing.Size(216, 21);

this.srcAddress.TabIndex = 2;

this.srcAddress.Text = "";

//

// tarAddress

//

this.tarAddress.Location = new System.Drawing.Point(80, 72);

this.tarAddress.Name = "tarAddress";

this.tarAddress.Size = new System.Drawing.Size(216, 21);

this.tarAddress.TabIndex = 3;

this.tarAddress.Text = "";

//

// statusBar

//

this.statusBar.Location = new System.Drawing.Point(0, 151);

this.statusBar.Name = "statusBar";

this.statusBar.Size = new System.Drawing.Size(312, 22);

this.statusBar.TabIndex = 4;

//

// Start

//

this.Start.FlatStyle = System.Windows.Forms.FlatStyle.Flat;

this.Start.Location = new System.Drawing.Point(216, 112);

this.Start.Name = "Start";

this.Start.Size = new System.Drawing.Size(75, 24);

this.Start.TabIndex = 5;

this.Start.Text = "开始下载";

this.Start.Click += new System.EventHandler(this.Start_Click);

//

// Form1

//

this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);

this.ClientSize = new System.Drawing.Size(312, 173);

this.Controls.Add(this.button1);

this.Controls.Add(this.Start);

this.Controls.Add(this.statusBar);

this.Controls.Add(this.tarAddress);

this.Controls.Add(this.srcAddress);

this.Controls.Add(this.label2);

this.Controls.Add(this.label1);

this.MaximizeBox = false;

this.Name = "Form1";

this.Text = "文件下载器";

this.ResumeLayout(false);

}

#endregion

///

/// 应用程序的主入口点。

///

[STAThread]

static void Main()

{

Application.Run(new Form1());

}

private void StartDownload()

{

Start.Enabled = false;

string URL = srcAddress.Text;

int n = URL.LastIndexOf("?");

string URLAddress = URL;

//string URLAddress = URL.Substring(0,n);

string fileName = URL.Substring(n+1,URL.Length-n-1);

string Dir = tarAddress.Text;

string Path = Dir+fileName;

try

{

WebRequest myre=WebRequest.Create(URLAddress);

}

catch(WebException exp)

{

MessageBox.Show(exp.Message,"Error");

}

try

{

statusBar.Text = "开始下载文件...";

client.DownloadFile(URLAddress,fileName);

Stream str = client.OpenRead(URLAddress);

//StreamReader reader = new StreamReader(str); ,这句没有什么必要！个人认为

byte[] mbyte = new byte[100000];

int allmybyte = (int)mbyte.Length;

int startmbyte = 0;

statusBar.Text = "正在接收数据...";

//写入到BYTE数组中，起缓冲作用

while(allmybyte>0)

{

int m = str.Read(mbyte,startmbyte,allmybyte);

if(m==0)

break;

startmbyte+=m;

allmybyte-=m;

}

FileStream fstr = new FileStream(Path,FileMode.OpenOrCreate,FileAccess.Write);

fstr.Write(mbyte,0,startmbyte);

str.Close();

fstr.Close();

statusBar.Text = "下载完毕！";

}

catch(WebException exp)

{

MessageBox.Show(exp.Message,"Error");

statusBar.Text = "";

}

Start.Enabled = true;

}

private void Start_Click(object sender, System.EventArgs e)

{

Thread th = new Thread(new ThreadStart(StartDownload));

th.Start();

}

}

}