asp.net斷點續傳

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)    {    // 創建一比特數組    byte[] buffer = new Byte[10240];    // 指定要下載文件的路徑.    string filePath = @"D:/愛智旮旯.rar";    // 或取文件名包括擴展名    string fileName = Path.GetFileName(filePath);    Stream fileStream = null;    try    {    // 打開文件    fileStream = new FileStream(filePath, FileMode.Open, Fileaccess.Read, FileShare.Read);    Response.Clear();    // 獲取文件的大小    long fileSize = fileStream.Length;    long sum = 0;    if (Request.Headers["Range"] != null)    {    Response.StatusCode = 206; // 表示返回到客戶端的 HTTP 輸出狀態的整數。默認值為 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());    }    // 獲取部分http頭信息    Response.AddHeader("Content-Length", ((long)(fileSize - sum)).ToString());    Response.ContentType = "application/octet-stream";    //獲取文件來源    Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(Request.ContentEncoding.GetBytes(fileName)));    // Response.Flush();    fileStream.Position = sum; //設置當前流位置    fileSize = fileSize - sum;    // 當文件大小大于0是進入循環    while (fileSize > 0)    {    // 判斷客戶端是否仍連接在服務器    if (Response.IsClientConnected)    {    // 獲取緩沖區中的總字節數.    int length = fileStream.Read(buffer, 0, 10240);    // 寫入數據    Response.OutputStream.Write(buffer, 0, length);    // 將緩沖區的輸出發送到客戶端    Response.Flush();    buffer = new Byte[10240];    fileSize = fileSize - length;    }    else    {    //當用戶斷開后退出循環    fileSize = -1;    }    }    }    catch (Exception ex)    {    Response.Write("Error : " + ex.Message);    }    finally    {    if (fileStream != null)    {    //關閉文件    fileStream.Close();    }    Response.End();    }    }    }