.text urlRewrite介绍

里我详细分析下。
  它实现了IHttpHandlerFactory
  (看注释就知道这个类是很重要的了)
  
  
  HttpModule处理完后(这句话并不正确，在这里是这样的)进入HttpHandler Factory,根据HttpHandler的配置内容我们可以马上找到这个类
  UrlReWriteHandlerFactory它是处理重写URL请求核心，在这里我详细分析下。
  它实现了IHttpHandlerFactory
  (看注释就知道这个类是很重要的了)
  
  using System;
  using System.Web;
  using System.Web.UI;
  using System.Text.RegularExpressions;
  
  using Dottext.Framework;
  using Dottext.Framework.Components;
  using Dottext.Framework.Configuration;
  
  namespace Dottext.Common.UrlManager
  {
   /**//// <summary>
   /// Class responisble for figuring out which .Text page to load. By default will load an array of Dottext.UrlManager.HttpHanlder
   /// from the blog.config file. This contains a list of Regex patterns to match the current request to. It also allows caching of the
   /// Regex's and Types
   /// </summary>
   public class UrlReWriteHandlerFactory: IHttpHandlerFactory
   {
   public UrlReWriteHandlerFactory(){} //Nothing to do in the cnstr
   //自定义虚方法从自定义配置节内容反序列化时构造Httphandler
   protected virtual HttpHandler[] GetHttpHandlers(HttpContext context)
   {
   return HandlerConfiguration.Instance().HttpHandlers;
   }
  
   /**//// <summary>
   /// Implementation of IHttpHandlerFactory. By default, it will load an array of HttpHanlder (Dottext.UrlManager.HttpHandler) from
   /// the blog.config. This can be changed, by overrideing the GetHttpHandlers(HttpContext context) method.
   /// </summary>
   /// <param name="context">Current HttpContext</param>
   /// <param name="requestType">Request Type (Passed along to other IHttpHandlerFactory's)</param>
   /// <param name="url">The current requested url. (Passed along to other IHttpHandlerFactory's)</param>
   /// <param name="path">The physical path of the current request. Is not gaurenteed to exist (Passed along to other IHttpHandlerFactory's)</param>
   /// <returns>
   /// Returns an Instance of IHttpHandler either by loading an instance of IHttpHandler or by returning an other
   /// IHttpHandlerFactory.GetHanlder(HttpContext context, string requestType, string url, string path) method
   /// </returns>
   //实现接口IHttpHandlerFactory定义的方法
   public virtual IHttpHandler GetHandler(HttpContext context, string requestType, string url, string path)
   {
   //Get the Handlers to process. By defualt, we grab them from the blog.config
   HttpHandler[] items = GetHttpHandlers(context);
   //Dottext.Framework.Logger.LogManager.Log("path",Dottext.Framework.Util.Globals.RemoveAppFromPath(context.Request.Path,context.Request.ApplicationPath));
   //Do we have any?
   if(items != null)
   {
   int count = items.Length;
  
   for(int i = 0; i<count; i++)
   {
   //We should use our own cached Regex. This should limit the number of Regex's created
   //and allows us to take advantage of RegexOptons.Compiled
   //逐个匹配所配置节中定义的请求类型
   if(items[i].IsMatch(Dottext.Framework.Util.Globals.RemoveAppFromPath(context.Request.Path,context.Request.ApplicationPath)))
   {
   //注意这里是关键，注意返回的Httphandler实例
   //throw new Exception();
   switch(items[i].HandlerType)
   {
   case HandlerType.Page://默认是Page
  
   return ProccessHandlerTypePage(items[i],context,requestType,url);
   case HandlerType.Direct:
   HandlerConfiguration.SetControls(context,items[i].BlogControls);
   return (IHttpHandler)items[i].Instance();
   case HandlerType.Factory:
   //Pass a long the request to a custom IHttpHandlerFactory
   return ((IHttpHandlerFactory)items[i].Instance()).GetHandler(context,requestType,url,path);
   default:
   throw new Exception("Invalid HandlerType: Unknown");
   }
   }
   }
   }
   //If we do not find the page, just let ASP.NET take over
   return PageHandlerFactory.GetHandler(context,requestType,url, path);
   }
  
  
   private IHttpHandler ProccessHandlerTypePage(HttpHandler item, HttpContext context, string requestType, string url)
   {
   string pagepath = item.FullPageLocation;
   if(pagepath == null)
   {
   pagepath = HandlerConfiguration.Instance().FullPageLocation;
   }
   HandlerConfiguration.SetControls(context,item.BlogControls);
   IHttpHandler myhandler=PageParser.GetCompiledPageInstance(url,pagepath,context);