asp.net下载，支持中文名，断点续传，控制单线程下载速度

using System;

using System.Data;

using System.Configuration;

using System.Linq;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.HtmlControls;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Xml.Linq;

using System.IO;

namespace lianxi

{

public class Download

{

public Download()

{

}

public static void DownloadFile(HttpResponse Response, HttpRequest Request, string filepath, int speed)

{

if (!File.Exists(filepath))

{

Response.StatusCode = 404; //http状态代码，具体请看http://hi.baidu.com/%C3%AB%CE%D1/blog/item/7066a154993750133b2935ab.html

return;

}

string name = Path.GetFileName(filepath); //获取文件名

int packSize = 10240;

byte[] buffer = new byte[packSize];

long fileLength;

long startByets = 0;

FileStream fs = new FileStream(filepath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

BinaryReader br = new BinaryReader(fs);

fileLength = fs.Length;

int sleep = (int)Math.Ceiling(1000.0 * packSize / speed); //用于单线程控制下载速度

try

{

Response.Clear();

Response.ClearHeaders();

Response.Buffer = false;

if (Request.Headers["Range"] != null)

{

Response.StatusCode = 206; //这个续传是必备的

startByets = long.Parse(Request.Headers["Range"].Replace("bytes=", "").Replace("-", "")); //获取客户端已经下载的字节数

}

if (startByets != 0)

{

Response.AddHeader("Content-Range", string.Format("bytes {0}-{1}/{2}", startByets, fileLength - 1, fileLength)); //续传必备，表示客户端从哪个字节开始下载，到哪个字节结束下载，具体请看http://hi.baidu.com/%C3%AB%CE%D1/blog/item/a630dfd3c18dbbd3a8ec9afc.html中的“Content-Range”，注意“fileLength
- 1”，这是有点像数组，用文件的长度-1就可以得到数组的最后字节了。

}

Response.AddHeader("Content-Length", fileLength.ToString()); //告诉客户端所要下载文件的长度

Response.AddHeader("Accept-Ranges", "bytes"); //续传必备

Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(name, System.Text.Encoding.UTF8));//用于支持英文文件名

Response.ContentType = "application/octet-stream"; //一般是这个，这个请看http://baike.baidu.com/view/160611.htm（MIME百科）

Response.ContentEncoding = System.Text.Encoding.UTF8;

fs.Seek(startByets, SeekOrigin.Begin);//设置文件流的起点位置

int maxCount = (int)Math.Ceiling((fileLength - startByets + 0.0) / packSize);

for (int i = 0; i < maxCount && Response.IsClientConnected; i++)

{

//int length = fs.Read(buffer, 0, packSize);

//Response.OutputStream.Write(buffer, 0, packSize);

Response.BinaryWrite(br.ReadBytes(packSize));

Response.Flush();

if (sleep > 0) System.Threading.Thread.Sleep(sleep);

}

}

catch (Exception ex)

{

Response.Write(ex.Message);

}

finally

{

fs.Close();

}

}

}

}