asp.net-自定义HttpModule与HttpHandler

在之前的ASP.NET是如何在IIS下工作的这篇文章中介绍了ASP.NET与IIS配合工作的机制，在http请求经过一系列处理后，最后到达ASP.NET管道中，这时，就是Http Modules和HttpHandler出场的时候了。

　　再来摆出管道工作时序图来一看：

HttpModule

HttpModule是类似于过滤器的作用，可以没有，也可以有任意个，每一个都可以订阅管道事件中的任意个事件，在每个订阅的事件中可自定义功能实现。

HttpModule是实现IHttpModule接口的类。接口如下：

public interface IHttpModule    {        // 摘要:         //     处置由实现 System.Web.IHttpModule 的模块使用的资源（内存除外）。        void Dispose();        //        // 摘要:         //     初始化模块，并使其为处理请求做好准备。        //        // 参数:         //  context:        //  一个 System.Web.Httpapplication，它提供对 ASP.NET 应用程序内所有应用程序对象的公用的方法、属性和事件的访问        void Init(HttpApplication context);    }

下面实现一个HttpModule，并订阅管道中的一系列事件,订阅事件就是在Init方法中绑定EventHandler的过程：

代码有点长，因为我把每一个事件都订阅了，这样一来可以清楚的看出哪些事件执行了，这些事件执行的先后顺序是什么。代码如下：

public class MyModule : IHttpModule    {        #region IHttpModule Members        public void Dispose()        {            //此处放置清除代码。        }        public void Init(HttpApplication context)        {            // 下面是如何处理 LogRequest 事件并为其             // 提供自定义日志记录实现的示例            context.LogRequest += new EventHandler(OnLogRequest);            context.BeginRequest += new EventHandler(context_BeginRequest);            context.AuthenticateRequest += new EventHandler(context_AuthenticateRequest);            context.AcquireRequestState += new EventHandler(context_AcquireRequestState);            context.AuthorizeRequest += new EventHandler(context_AuthorizeRequest);            context.Disposed += new EventHandler(context_Disposed);            context.Error += new EventHandler(context_Error);            context.EndRequest += new EventHandler(context_EndRequest);            context.MaPRequestHandler += new EventHandler(context_MapRequestHandler);            context.PostAcquireRequestState += new EventHandler(context_PostAcquireRequestState);            context.PostAuthenticateRequest += new EventHandler(context_PostAuthenticateRequest);            context.PostAuthorizeRequest += new EventHandler(context_PostAuthorizeRequest);            context.PostLogRequest += new EventHandler(context_PostLogRequest);            context.PostReleaseRequestState += new EventHandler(context_PostReleaseRequestState);            context.PostRequestHandlerExecute += new EventHandler(context_PostRequestHandlerExecute);            context.PostResolveRequestCache += new EventHandler(context_PostResolveRequestCache);            context.PostUpdateRequestCache += new EventHandler(context_PostUpdateRequestCache);            context.ReleaseRequestState += new EventHandler(context_ReleaseRequestState);            context.RequestCompleted += new EventHandler(context_RequestCompleted);            context.ResolveRequestCache += new EventHandler(context_ResolveRequestCache);            context.UpdateRequestCache += new EventHandler(context_UpdateRequestCache);            context.PreRequestHandlerExecute += new EventHandler(context_PreRequestHandlerExecute);            context.PreSendRequestContent += new EventHandler(context_PreSendRequestContent);            context.PreSendRequestHeaders += new EventHandler(context_PreSendRequestHeaders);            context.PostMapRequestHandler += new EventHandler(context_PostMapRequestHandler);        }        void context_Error(object sender, EventArgs e)        {            WriteLog("Error");            //HttpContext.Current.Response.Write("Error<br />");        }        void context_UpdateRequestCache(object sender, EventArgs e)        {            WriteLog("UpdateRequestCache");            //HttpContext.Current.Response.Write("UpdateRequestCache<br />");        }        void context_ResolveRequestCache(object sender, EventArgs e)        {            WriteLog("ResolveRequestCache");            // HttpContext.Current.Response.Write("ResolveRequestCache<br />");        }        void context_RequestCompleted(object sender, EventArgs e)        {            WriteLog("RequestCompleted");            // HttpContext.Current.Response.Write("RequestCompleted<br />");        }        void context_ReleaseRequestState(object sender, EventArgs e)        {            WriteLog("ReleaseRequestState");            //HttpContext.Current.Response.Write("ReleaseRequestState<br />");        }        void context_PostUpdateRequestCache(object sender, EventArgs e)        {            WriteLog("PostUpdateRequestCache");            //HttpContext.Current.Response.Write("PostUpdateRequestCache<br />");        }        void context_PostResolveRequestCache(object sender, EventArgs e)        {            WriteLog("PostResolveRequestCache");            //HttpContext.Current.Response.Write("PostResolveRequestCache<br />");        }        void context_PostRequestHandlerExecute(object sender, EventArgs e)        {            WriteLog("PostRequestHandlerExecute");            //HttpContext.Current.Response.Write("PostRequestHandlerExecute<br />");        }        void context_PostReleaseRequestState(object sender, EventArgs e)        {            WriteLog("PostReleaseRequestState");            //HttpContext.Current.Response.Write("PostReleaseRequestState<br />");        }        void context_PostLogRequest(object sender, EventArgs e)        {            WriteLog("PostLogRequest");            //HttpContext.Current.Response.Write("PostLogRequest<br />");        }        void context_PostAuthorizeRequest(object sender, EventArgs e)        {            WriteLog("PostAuthorizeRequest");            //HttpContext.Current.Response.Write("PostAuthorizeRequest<br />");        }        void context_PostAuthenticateRequest(object sender, EventArgs e)        {            WriteLog("PostAuthenticateRequest");            //HttpContext.Current.Response.Write("PostAuthenticateRequest<br />");        }        void context_PostAcquireRequestState(object sender, EventArgs e)        {            WriteLog("PostAcquireRequestState");            //HttpContext.Current.Response.Write("PostAcquireRequestState<br />");        }        void context_MapRequestHandler(object sender, EventArgs e)        {            WriteLog("MapRequestHandler");            //HttpContext.Current.Response.Write("MapRequestHandler<br />");        }        void context_Disposed(object sender, EventArgs e)        {            WriteLog("Disposed");            //HttpContext.Current.Response.Write("Disposed<br />");        }        void context_AuthorizeRequest(object sender, EventArgs e)        {            WriteLog("AuthorizeRequest");            //HttpContext.Current.Response.Write("AuthorizeRequest<br />");        }        void context_AcquireRequestState(object sender, EventArgs e)        {            WriteLog("AcquireRequestState");            //HttpContext.Current.Response.Write("AcquireRequestState<br />");        }        void context_PreSendRequestHeaders(object sender, EventArgs e)        {            WriteLog("PreSendRequestHeaders");            //HttpContext.Current.Response.Write("PreSendRequestHeaders<br />");        }        void context_PreSendRequestContent(object sender, EventArgs e)        {            WriteLog("PreSendRequestContent");            //HttpContext.Current.Response.Write("PreSendRequestContent<br />");        }        void context_PreRequestHandlerExecute(object sender, EventArgs e)        {            WriteLog("PreRequestHandlerExecute");            //HttpContext.Current.Response.Write("PreRequestHandlerExecute<br />");        }        void context_EndRequest(object sender, EventArgs e)        {            WriteLog("EndRequest");            //HttpContext.Current.Response.Write("EndRequest<br />");        }        void context_BeginRequest(object sender, EventArgs e)        {            Wr