学步园

namespace HandlerAndModule
{
    public class ImageHandler:IHttpHandler
    {
        #region IHttpHandler 成员

        public bool IsReusable
        {
            get { return true; }
        }

        public void ProcessRequest(System.Web.HttpContext context)
        {
            //获取当前Request对象
            HttpRequest req = context.Request;
            //从Request对象中获取所请求文件的物理路径
            string IMG_Path = req.PhysicalPath;
            string ContentType;

            //判断请求的URL是否为本站内的URL
            if (req.UrlReferrer != null && req.UrlReferrer.Host.Length > 0)
            {
                if (CultureInfo.InvariantCulture.CompareInfo.Compare(req.Url.Host, req.UrlReferrer.Host, CompareOptions.IgnoreCase) != 0)
                {
                    IMG_Path = context.Server.MapPath("~/images/error.gif");
                }
            }

            //根据路径名获取输出内容类型
            ContentType = GetContentType(IMG_Path);

            //判断文件是否存在
            if (File.Exists(IMG_Path))
            {
                context.Response.StatusCode = 200;
                context.Response.ContentType = ContentType;
                context.Response.WriteFile(IMG_Path);
            }
            else
            {
                context.Response.StatusCode = 404;
                context.Response.Status = "无法找到您请求的文件";
            }
        }

        #endregion

        /// <summary>
        /// 此方法用于从路径获取输出的MIME类型
        /// </summary>
        /// <param name="path">文件路径</param>
        /// <returns>对应的MIME类型</returns>
        private string GetContentType(string path)
        {
            //获取文件的扩展名
            string extension = Path.GetExtension(path);
            string contentType;
            //判断扩展名对应的Mime类型
            switch (extension)
            {
                case ".gif":
                    contentType = "image/gif";
                    break;
                case "image/jpeg":
                    contentType = "image/jpeg";
                    break;
                case ".png":
                    contentType = "image/png";
                    break;
                default:
                    contentType = "";
                    break;
            }
            //返回mime类型
            return contentType;
        }
    }
}

namespace HandlerFactory
{
    public class RARHandler:IHttpHandler,System.Web.SessionState.IRequiresSessionState
    {
        #region IHttpHandler 成员

        public bool IsReusable
        {
            get { return true; }
        }

        public void ProcessRequest(HttpContext context)
        {
            HttpRequest req = context.Request;
            //从Request对象中获取所请求文件的物理路径
            string RAR_Path = req.PhysicalPath;
            //设置HTTP输出的MIME类型
            string ContentType = "application/x-tar";
            //根据Session中UserName是否存在判断用户是否登陆
            if (context.Session["UserName"] == null)
            {
                //未登陆则设置状态代码为404
                context.Response.StatusCode = 404;
                context.Response.End();
            }
            else
            {
                //登陆则输出RAR文件
                context.Response.StatusCode = 200;
                context.Response.ContentType = ContentType;
                context.Response.WriteFile(RAR_Path);
            }
        }

        #endregion
    }
}

namespace HandlerFactory
{
    public class MyHandlerFactory:IHttpHandlerFactory
    {
        #region IHttpHandlerFactory 成员

        IHttpHandler IHttpHandlerFactory.GetHandler(HttpContext context, string requestType, string url, string pathTranslated)
        {
            //判断文件扩展名
            if (url.EndsWith(".jpeg", StringComparison.InvariantCultureIgnoreCase) || url.EndsWith(".jpg", StringComparison.InvariantCultureIgnoreCase))
                //实例化并返回一个JPGHandler
                return new JPGHandler();
            else if (url.EndsWith(".rar", StringComparison.InvariantCultureIgnoreCase))
                //实例化并返回一个RARHandler
                return new RARHandler();
            else
                return null;
        }

        void IHttpHandlerFactory.ReleaseHandler(IHttpHandler handler)
        {
        }

        #endregion
    }
}

namespace HandlerAndModule
{
    public class IPModule:IHttpModule
    {
        #region IHttpModule 成员

        public void Dispose()
        {
        }

        public void Init(HttpApplication context)
        {
            context.BeginRequest += new EventHandler(OnBeginRequest);
        }

        #endregion

        private void OnBeginRequest(object sender, EventArgs e)
        {
            HttpApplication app = sender as HttpApplication;
            if (app != null)
            {
                if(isBadIPAddr(app.Context))
                {
                    app.Context.Response.StatusCode = 404;
                    app.Context.Response.End();
                }
            }
        }

        private bool isBadIPAddr(HttpContext context)
        {
            string ip = context.Request.UserHostAddress;
            StringDictionary sdic = new StringDictionary();
            sdic.Add("127.0.0.0", "127.0.0.0");
            if (sdic.ContainsKey(ip))
                return true;
            else
                return false;
        }
    }
}