HttpModule是如何工作的 当一个HTTP请求到达HttpModule时，整个ASP.NET Framework系统还并没有对这个HTTP请求做任何处理，也就是说此时对于HTTP请求来讲，HttpModule是一个HTTP请求的“必经之路”，所以可以在这个HTTP请求传递到真正的请求处理中心（HttpHandler）之前附加一些需要的信息在这个HTTP请求信息之上，或者针对截获的这个HTTP请求信息作一些额外的工作，或者在某些情况下干脆终止满足一些条件的HTTP请求，从而可以起到一个Filter过滤器的作用。 示例1： using System; using System.Collections.Generic; using System.Text; using System.Web; namespace MyHttpModule { ///<summary> /// 说明：用来实现自己的HttpModule类。 /// 作者：文野 /// 联系：[email protected] ///</summary> public class MyFirstHttpModule : IHttpModule { private void Application_BeginRequest(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; HttpContext context = application.Context; HttpRequest request = application.Request; HttpResponse response = application.Response; response.Write(" 我来自自定义HttpModule中的BeginRequest<br />" ); } private void Application_EndRequest(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; HttpContext context = application.Context; HttpRequest request = application.Request; HttpResponse response = application.Response; response.Write(" 我来自自定义HttpModule中的EndRequest<br />" ); } #region IHttpModule 成员 public void Dispose() {} public void Init(HttpApplication application) { application.BeginRequest += new EventHandler(Application_BeginRequest); application.EndRequest += new EventHandler(Application_EndRequest); } #endregion } } 在Web.config进行如下配置 < add name = "MyFirstHttpModule"type="MyHttpModule.MyFirstHttpModule,MyHttpModule"/>
深入了解 HttpModule 一个HTTP请求在HttpModule容器的传递过程中，会在某一时刻（ResolveRequestCache事件）将这个HTTP请求传递给HttpHandler容器。在这个事件之后，HttpModule容器会建立一个HttpHandler的入口实例，但是此时并没有将HTTP请求控制权交出，而是继续触发AcquireRequestState事件以及PreRequestHandlerExcute事件。在PreRequestHandlerExcute事件之后，HttpModule窗口就会将控制权暂时交给HttpHandler容器，以便进行真正的HTTP请求处理工作。 而在HttpHandler容器内部会执行ProcessRequest方法来处理HTTP请求。在容器HttpHandler处理完毕整个HTTP请求之后，会将控制权交还给HttpModule，HttpModule则会继续对处理完毕的HTTP请求信息流进行层层的转交动作，直到返回到客户端为止。
图1：HttpModule生命周期示意图 示例2：验证HttpModule生命周期 using System; using System.Collections.Generic; using System.Text; using System.Web; namespace MyHttpModule { public class ValidaterHttpModule : IHttpModule { #region IHttpModule 成员 public void Dispose() {} public void Init(HttpApplication application) { application.BeginRequest += new EventHandler(application_BeginRequest); application.EndRequest += new EventHandler(application_EndRequest); application.PreRequestHandlerExecute += new EventHandler(application_PreRequestHandlerExecute); application.PostRequestHandlerExecute += new EventHandler(application_PostRequestHandlerExecute); application.ReleaseRequestState += new EventHandler(application_ReleaseRequestState); application.AcquireRequestState += new EventHandler(application_AcquireRequestState); application.AuthenticateRequest += new EventHandler(application_AuthenticateRequest); application.AuthorizeRequest += new EventHandler(application_AuthorizeRequest); application.ResolveRequestCache += new EventHandler(application_ResolveRequestCache); application.PreSendRequestHeaders += new EventHandler(application_PreSendRequestHeaders); application.PreSendRequestContent += new EventHandler(application_PreSendRequestContent); } void application_PreSendRequestContent(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_PreSendRequestContent<br/>"); } void application_PreSendRequestHeaders(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_PreSendRequestHeaders<br/>"); } void application_ResolveRequestCache(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_ResolveRequestCache<br/>"); } void application_AuthorizeRequest(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_AuthorizeRequest<br/>"); } void application_AuthenticateRequest(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_AuthenticateRequest<br/>"); } void application_AcquireRequestState(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_AcquireRequestState<br/>"); } void application_ReleaseRequestState(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_ReleaseRequestState<br/>"); } void application_PostRequestHandlerExecute(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_PostRequestHandlerExecute<br/>"); } void application_PreRequestHandlerExecute(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_PreRequestHandlerExecute<br/>"); } void application_EndRequest(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_EndRequest<br/>"); } void application_BeginRequest(object sender, EventArgs e) { HttpApplication application = (HttpApplication)sender; application.Context.Response.Write("application_BeginRequest<br/>"); } #endregion } }