File Downloader ASP.NET

using System;
using System.Collections.Generic;
using System.Collections;
using System.ComponentModel;

using System.Data;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Data.OleDb;
using System.Data.Common;
using System.Data.SqlTypes;
using System.Data.ProviderBase;

using System.Text;
using System.Threading;
using System.IO;
using System.Net;
using System.Diagnostics;

using System.Xml;
using System.Xml.Serialization;
using System.Xml.Schema;
using System.Xml.XPath;
using System.Xml.Xsl;

using System.Configuration;

using System.Globalization;
using System.Reflection;
using System.Data.SqlClient;
using System.Data.Common;
using System.Drawing;

using System.Web;
using System.Web.Util;
using System.Web.UI;
using System.Web.SessionState;
using System.Web.Security;
using System.Web.Profile;
using System.Web.Mail;
using System.Web.Handlers;
using System.Web.Hosting;
using System.Web.DataAccess;
using System.Web.Configuration;
using System.Web.Compilation;
using System.Web.Caching;
using System.Web.Administration;
using System.Web.Services;
using System.Web.Services.Configuration;
using System.Web.Services.Description;
using System.Web.Services.Protocols;
using System.Web.UI.WebControls;
/*
    void Application_BeginRequest(object sender, EventArgs e) {

        HttpRequest Request = HttpContext.Current.Request;
        HttpResponse Response = HttpContext.Current.Response;
        HttpServerUtility Server = HttpContext.Current.Server;
        HttpContext Context = HttpContext.Current;
        if (Request.Path.EndsWith(".fdl")) {
            FileDownloadHandler handler=new FileDownloadHandler();
            handler.ProcessRequest(HttpContext.Current);
        }
    }
 */
public class FileDownloadParameter {

    public static string Serialize(FileDownloadParameter cs) {
        return XmlHelpers.SerializeObject(cs, typeof(FileDownloadParameter));
    }
    public static FileDownloadParameter Deserialize(string base64) {
        return (FileDownloadParameter)XmlHelpers.DeserializeObject(base64, typeof(FileDownloadParameter));
    }

    //public const string FileTypeQueryString = "filetype,ft,f";
    //public const string FileNameconstQueryString = "filename,fn,n";
    //public const string DownloadKeyconstQueryString = "downloadkey,key,k";


    private string m_FileType;
    public string FileType {
        get { return m_FileType; }
        set { m_FileType = value; }
    }

    private string m_FileName;
    public string FileName {
        get { return m_FileName; }
        set { m_FileName = value; }
    }

    private string m_DownloadKey;
    public string DownloadKey {
        get { return m_DownloadKey; }
        set { m_DownloadKey = value; }
    }


    private object m_FileData;
    public object FileData {
        get { return m_FileData; }
        set { m_FileData = value; }
    }


    public FileDownloadParameter() {
    }

    public FileDownloadParameter(string p_FileType,
        string p_FileName,
        string p_DownloadKey)
        : this() {
        this.m_FileType = p_FileType;
        this.m_FileName = p_FileName;
        this.m_DownloadKey = p_DownloadKey;

    }

}
public class FileDownloader {

    public static void DownloadFile(FileDownloadParameter parameters) {
        string url = GetDowloadFileUrl(parameters);
        Response.Redirect(url, true);
    }
    public static void DownloadFile(string p_FileType,
        string p_FileName,
        object fileData) {
        FileDownloadParameter p= new FileDownloadParameter();
        p.FileType = p_FileType;
        p.FileName = p_FileName;
        p.FileData = fileData;

        DownloadFile(p);
    }

    public static string GetDowloadFileUrl(FileDownloadParameter parameters) {
        string key = Guid.NewGuid().ToString();
        parameters.DownloadKey = key;
        string url = "filedownload.aspx?k=" + key;
        HttpContext.Current.Cache.Insert(key, parameters, null, DateTime.MaxValue, new TimeSpan(8, 0, 0));
        return url;
    }
    public static string GetDowloadFileUrl(string p_FileType,
        string p_FileName,
        object fileData) {
        FileDownloadParameter p= new FileDownloadParameter();
        p.FileType = p_FileType;
        p.FileName = p_FileName;
        p.FileData = fileData;

        return GetDowloadFileUrl(p);
    }
    public static FileDownloadParameter GetDataFromKey(string downloadKey) {
        return (FileDownloadParameter) HttpContext.Current.Cache[downloadKey];

    }
    private static HttpResponse Response {
        get { return HttpContext.Current.Response; }
    }
}

public class FileDownloadHandler : IHttpHandler {

    public void ProcessRequest (HttpContext context) {


        HttpRequest Request = HttpContext.Current.Request;
        HttpResponse Response = HttpContext.Current.Response;
        HttpServerUtility Server = HttpContext.Current.Server;
        HttpContext Context = HttpContext.Current;

        string key = Request.QueryString["k"];
        if (string.IsNullOrEmpty(key))
            return;

        FileDownloadParameter parameter = FileDownloader.GetDataFromKey(key);
        if (parameter ==null)
            return;

        string id = parameter.DownloadKey;
        string filetype = parameter.FileType;
        string filename = parameter.FileName;
        object fileData = parameter.FileData;

        if (string.IsNullOrEmpty(filename))
            filename = "export." + filetype;

        Response.ClearHeaders();
        if (filetype == "csv") {
            string csvData = fileData.ToString();
            Response.ContentType = "text/csv";
            Response.AddHeader("Content-Disposition", "attachment;filename=" + filename);
            Response.AddHeader("Content-Length", csvData.Length.ToString());
            Response.Write(csvData);
        }
        if (filetype == "txt") {
            string csvData = fileData.ToString();
            Response.ContentType = "text/text";
            Response.AddHeader("Content-Disposition", "attachment;filename=" + filename);
            Response.AddHeader("Content-Length", csvData.Length.ToString());
            Response.Write(csvData);
        }
        if (filetype == "xls") {
            MemoryStream contents = fileData as MemoryStream;
            contents.Position = 0;
            Response.ContentType = "application/vnd.ms-excel";
            Response.AddHeader("Content-Disposition", "attachment;filename=" + filename);
            Response.BinaryWrite(contents.ToArray());
        }
        if (filetype == "rtf") {
            MemoryStream contents = fileData as MemoryStream;
            contents.Position = 0;
            Response.ContentType = "application/vnd.ms-word";
            Response.AddHeader("Content-Disposition", "attachment;filename=" + filename);
            Response.BinaryWrite(contents.ToArray());
        }
        if (filetype == "pdf") {
            MemoryStream contents = fileData as MemoryStream;
            contents.Position = 0;
            Response.ContentType = "application/pdf";
            Response.AddHeader("Content-Disposition", "attachment;filename=" + filename);
            Response.BinaryWrite(contents.ToArray());
        }

        Response.End();

    }

    public bool IsReusable {
        get {
            return true;
        }
    }

}