Simple file IHttpHandler

FileHandler.cs

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.IO;
using System.Collections.Generic;

public class FileHandler : IHttpHandler
{
    public FileHandler() { }

    #region IHttpHandler Members

    public bool IsReusable
    {
        get { return false; }
    }

    public void ProcessRequest(HttpContext context)
    {
        string fn = getFileName(context);
        if (!File.Exists(fn))
        {
            throw new HttpException(404, "File Not Found");
        }
        else
        {
            FileInfo fi=new FileInfo(fn);
            context.Response.ContentType = getContentType(fi.Extension);
            context.Response.AddHeader("content-disposition", string.Format("attachment; filename={0}", fi.Name));
            context.Response.WriteFile(fn);
            context.Response.End();
        }
    }

    private string getContentType(string ext)
    {
        string ret = null;
        switch (ext)
        {
            case "doc":
                ret = "application/msword";
                break;
            case "xls":
                ret="application/vnd.ms-excel";
                break;
            case "ppt":
                ret = "application/vnd.ms-powerpoint";
                break;
            case "zip":
                ret = "application/zip";
                break;
            case "txt":
                ret = "text/plain";
                break;
            case "html":
            case "htm":
                ret = "text/html";
                break;
            default:
                ret = "application/octet-stream";
                break;
        }
        return ret;
    }

    private string getFileName(HttpContext context)
    {
        Stack<string> ss = new Stack<string>(context.Request.Url.Segments);
        string tmp = ss.Pop();
        tmp = tmp.Substring(0, tmp.Length - 5);
        return context.Server.MapPath(string.Format("~/App_Data/{0}", tmp));
    }

    #endregion
}