asp.net 文件下载，有进度条

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="RenameDownload.aspx.cs" Inherits="DownloadProxy.RenameDownload" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script src="Scripts/jquery-1.4.1.min.js" type="text/javascript"></script>
</head>
<body>
    <form id="form1" runat="server">
    <asp:scriptmanager runat="server" EnablePageMethods="true"></asp:scriptmanager>
    <script type="text/javascript">
        //PageMethods.set_timeout(5000);
        PageMethods.set_defaultFailedCallback = "OnFailed";
        setInterval(function () {
            PageMethods.GetDownloadBytes(function (result) {
                document.getElementById("cellProcess").innerHTML =  result;
            });
        }, 1000);

        function OnFailed(ErrorHander) {
            var ErrorMessage = 'Timeout:' + ErrorHander.get_timedOut() + ',Error Message：' + ErrorHander.get_message();
            ErrorMessage = ErrorMessage + ',Exception Type：' + ErrorHander.get_exceptionType() + ',Error Loaction：' + ErrorHander.get_stackTrace();
            alert(ErrorMessage);
        }

        function DownloadFile(obj) {
            PageMethods.DownloadFile("https://download.alipay.com/sec/edit/aliedit.exe", "C:\\Documents and Settings\\kn73\\Desktop\\aliedit.exe");
        }
    </script>
    <table>
        <tr>
            <td><input type="button" value="download" id="btnDownload" onclick="DownloadFile(this)" /></td>
            <td></td>
            <td></td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td></td>
            <td></td>
        </tr>
        <tr>
            <td>Bytes download:</td>
            <td id="cellProcess"></td>
            <td></td>
        </tr>
    </table>
    </form>
</body>
</html>

using System.Web.UI;
using System.Web.UI.WebControls;
using System.Net;
using System.IO;
using System.Threading;

namespace DownloadProxy
{
    public partial class RenameDownload : System.Web.UI.Page
    {
        public static long DownloadBytes { get; set; }

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                DownloadBytes = 0;
            }
        }

        [System.Web.Services.WebMethod]
        public static void DownloadFile(String remoteFilename, String localFilename)
        {
            var thread = new Thread(new ThreadStart(delegate() 
                {
                    DownloadFileProc(remoteFilename, localFilename);
                }));
            thread.Start();
        }

        public static long DownloadFileProc(String remoteFilename, String localFilename)
        {
            long bytesProcessed = 0;

            Stream remoteStream = null;
            Stream localStream = null;
            WebResponse response = null;

            try
            {
                // Create a request for the specified remote file name
                var request = (HttpWebRequest)WebRequest.Create(remoteFilename);
                request.AllowWriteStreamBuffering = true;
                request.Credentials = System.Net.CredentialCache.DefaultCredentials;
                request.Proxy = new WebProxy { UseDefaultCredentials = true };
                request.MaximumResponseHeadersLength = -1;
                request.Accept = "www/source, text/html, video/mpeg, image/jpeg, image/x-tiff, image/x-rgb, image/x-xbm, image/gif, application/postscript, application/x-gzip, */*, ";
                request.AllowAutoRedirect = true;
                request.UserAgent = "TLE Retriever v1.5.8";
                request.ContentType = "application/x-www-form-urlencoded";
                request.Method = "GET";
                request.Headers.Add("Accept-Language", "zh-cn");
                request.Headers.Add("Accept-Encoding", "gzip,deflate");
                request.KeepAlive = true;
                if (request != null)
                {
                    response = request.GetResponse();
                    if (response != null)
                    {
                        remoteStream = response.GetResponseStream();

                        // Create the local file
                        localStream = File.Create(localFilename);

                        // Allocate a 1k buffer
                        byte[] buffer = new byte[1024];
                        int bytesRead;

                        // Simple do/while loop to read from stream until
                        // no bytes are returned
                        do
                        {
                            // Read data (up to 1k) from the stream
                            bytesRead = remoteStream.Read(buffer, 0, buffer.Length);

                            // Write the data to the local file
                            localStream.Write(buffer, 0, bytesRead);

                            // Increment total bytes processed
                            bytesProcessed += bytesRead;

                            DownloadBytes = bytesProcessed;

                        } while (bytesRead > 0);
                    }
                }
            }
            catch
            {
                throw;
            }
            finally
            {
                if (response != null) response.Close();
                if (remoteStream != null) remoteStream.Close();
                if (localStream != null) localStream.Close();
            }

            // Return total bytes processed to caller.
            return bytesProcessed;
        }

        [System.Web.Services.WebMethod]
        public static long GetDownloadBytes()
        {
            return DownloadBytes;
        }
    }
}