asp.net断点续传

using System;

    using System.Data;

    using System.Configuration;

    using System.Collections;

    using System.Web;

    using System.Web.Security;

    using System.Web.UI;

    using System.Web.UI.WebControls;

    using System.Web.UI.WebControls.WebParts;

    using System.Web.UI.HtmlControls;

    using System.IO;

    public partial class DFile : System.Web.UI.Page

    {

    protected void Page_Load(object sender, EventArgs e)

    {

    }

    protected void LinBtnDFile_Click(object sender, EventArgs e)

    {

    // 创建一比特数组

    byte[] buffer = new Byte[10240];

    // 指定要下载文件的路径.

    string filePath = @"D:\爱智旮旯.rar";

    // 或取文件名包括扩展名

    string fileName = Path.GetFileName(filePath);

    Stream fileStream = null;

    try

    {

    // 打开文件

    fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);

    Response.Clear();

    // 获取文件的大小

    long fileSize = fileStream.Length;

    long sum = 0;

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

    {

    Response.StatusCode = 206; // 表示返回到客户端的 HTTP 输出状态的整数。默认值为 200。

    sum = long.Parse(Request.Headers["Range"].Replace("bytes=", "").Replace("-", ""));

    }

    if (sum != 0)

    {

    Response.AddHeader("Content-Range", "bytes " + sum.ToString() + "-" + ((long)(fileSize)).ToString() + "/" + fileSize.ToString());

    }

    // 获取部分http头信息

    Response.AddHeader("Content-Length", ((long)(fileSize - sum)).ToString());

    Response.ContentType = "application/octet-stream";

    //获取文件来源

    Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(Request.ContentEncoding.GetBytes(fileName)));

    // Response.Flush();

    fileStream.Position = sum; //设置当前流位置

    fileSize = fileSize - sum;

    // 当文件大小大于0是进入循环

    while (fileSize > 0)

    {

    // 判断客户端是否仍连接在服务器

    if (Response.IsClientConnected)

    {

    // 获取缓冲区中的总字节数.

    int length = fileStream.Read(buffer, 0, 10240);

    // 写入数据

    Response.OutputStream.Write(buffer, 0, length);

    // 将缓冲区的输出发送到客户端

    Response.Flush();

    buffer = new Byte[10240];

    fileSize = fileSize - length;

    }

    else

    {

    //当用户断开后退出循环

    fileSize = -1;

    }

    }

    }

    catch (Exception ex)

    {

    Response.Write("Error : " + ex.Message);

    }

    finally

    {

    if (fileStream != null)

    {

    //关闭文件

    fileStream.Close();

    }

    Response.End();

    }

    }

    }