A Smarter Way to Include JavaScripts and CSS to Reduce Page Load Times

/*
 * Smart Include
 * 
 * Copyright (c) 2010 Fredrik Schultz
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 * 
 */

using System;
using System.Web;

namespace Kaliko.SmartInclude {
    /// <summary>
    /// Used to return the correct compressed file to the browser.
    /// </summary>
    public class GetPackedFile : System.Web.UI.Page {
        protected void Page_Load(object sender, EventArgs e) {

            string type = Request.QueryString["t"];
            bool isCss = type == "css";
            string filename = Config.IncludeFilePath +
                              (Request.QueryString["v"] ?? "").Replace("..", "").Replace("\\", "").Replace("/", "") +
                              (isCss ? ".css" : ".js");

            Response.ContentType = isCss ? "text/css" : "text/javascript";

            if (Common.IsGzipAccepted) {
                filename += ".gz";
                Response.AddHeader("Content-Encoding", "gzip");
            }

            // Tell client to cache this exact version for a year. If any of the files 
            // that is included in the file is changed a new version will be created 
            // to replace this cached version.
            Response.Cache.SetCacheability(HttpCacheability.Private);
            Response.Cache.SetExpires(DateTime.Now.AddYears(1));
            Response.Cache.SetNoServerCaching();

            Response.WriteFile(filename);
            Response.End();

        }
    }
}