C# ASP.NET实现文件点击下载

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;


public partial class downloadDagang : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //if(!IsPostBack){
        string filepath = Request.QueryString["Url"];
        string filename = Path.GetFileName("教学大纲.doc");
        //E:\会计资料\会计学\校园网站管理\Image\dagang\教学大纲.doc
        FileStream fileStream = new FileStream(@"E:\会计资料\会计学\校园网站管理\" + filepath, FileMode.Open);
        long fileSize = fileStream.Length;
        Context.Response.ContentType = "application/octet-stream";
        Context.Response.AddHeader("Content-Disposition", "attachment; filename=/" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8) + "/");
        Context.Response.AddHeader("Content-Length", fileSize.ToString());
        byte[] fileBuffer = new byte[fileSize];
        fileStream.Read(fileBuffer, 0, (int)fileSize);
        fileStream.Close();
        Context.Response.BinaryWrite(fileBuffer);
        Context.Response.End();