一、IHttpModule相关概述
相关IHttpModule接口：using System;namespace System.Web{ public interface IHttpModule { // 销毁不再被HttpModule使用的资源 void Dispose(); // 初始化一个Module,为捕获HttpRequest做准备 void Init(HttpApplication context); }}
功能概述:向实现类提供模块初始化和处置事件.它能够截获所有请求,如同windows hook一样.所以你能够利用它做很多你想要做的事情.
必然url重写、大文件上传、sql注入检测......
Asp.net会为每个请求分配一个HttpApplication对象.
二、IIS7、IIS6 web.config注册HttpModule
1)IIS6注册HttpModule
2)IIS7注册HttpModule
<system.webServer>
<modules><add name="..." type="MyApplication.RequestDurationLoggerModule, MyApplication"/>
</modules>
</system.webServer>
三、动态注册
四、HttpModule的事件
参考:
| 事件名称 | 功能介绍 |
| BeginRequest | 指示请求处理开始 |
| AuthenticateRequest | 封装请求身份验证过程 |
| AuthorizeRequest | 封装检查是否能利用以前缓存的输出页面处理请求的过程 |
| ResolveRequestCache | 从缓存中得到响应时触发 |
| AcquireRequestState | 加载初始化Session时候触发 |
| PreRequestHandlerExecute | 在Http请求进入HttpHandler之前触发 |
| PostRequestHandlerExecute | 在Http请求进入HttpHandler之后触发 |
| ReleaseRequestState | 存储Session状态时候触发 |
| UpdateRequestCache | 更新缓存信息时触发 |
| EndRequest | 在Http请求处理完成的时候触发 |
| PreSendRequestHenaders | 在向客户端发送Header之前触发 |
| PreSendRequestConternt | 在向客户端发送内容之前触发 |
说明：
a、BenginRequest和EndRequest分别是HttpModule容器最开始的和最后的事件； b、EndRequest之后还会触发PreSendRequestHeaders事件和PreSendRequestContent事件，这不是在HttpModule外的两个事件，表示HttpModule结束，即将开始向Client发送数据。五、完整的httpmodule运行过程
说明： a、HttpModule容器会将HttpRequest传递到HttpHandler容器，这个时间点是ResolveRequestCache事件 b、HttpModule容器会建立HttpHandler实例作为入口——Session从此生效 c、触发AcquireRequestState事件以及PreRequestHandlerExecute事件 d、HttpModule容器便将对HttpRequest的控制权转让给HttpHandler容器 e、HttpHandler容器处理HttpRequest——使用自身的ProcessRequest方法，将对其控制权又还给HttpModule容器——之后Session失效。
再次说明：
a、对于一个HttpModule，在BeginRquest中终止，但是仍然会调用EndRequest事件，以及PreSendRequestHeaders事件和PreSendRequestContent事件。也可以说是直接跳转到EndRequest事件，而不会调用这期间的事件 b、如果有两个HttpModule，在第一个HttpModule的BeginRequest中终止，仅仅不会调用第二个HttpModule的BeginRequest，但仍然会调用两个EndRequest事件，以及PreSendRequestHeaders事件和PreSendRequestContent事件。看下面的图示：验证生命周期代码：
using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
namespace MyHttpModule
{ public class ValidaterHttpModuleEvents : IHttpModule
{ public void Dispose()
{ } ///
/// 验证HttpModule事件机制
///
///
public void Init(HttpApplication application)
{ application.BeginRequest += new EventHandler(application_BeginRequest);
application.EndRequest += new EventHandler(application_EndRequest);
application.AcquireRequestState += new EventHandler(application_AcquireRequestState);
application.AuthenticateRequest += new EventHandler(application_AuthenticateRequest);
application.AuthorizeRequest += new EventHandler(application_AuthorizeRequest);
application.PreRequestHandlerExecute += new EventHandler(application_PreRequestHandlerExecute);
application.PostRequestHandlerExecute += new EventHandler(application_PostRequestHandlerExecute);
application.ReleaseRequestState += new EventHandler(application_ReleaseRequestState);
application.ResolveRequestCache += new EventHandler(application_ResolveRequestCache);
application.PreSendRequestHeaders += new EventHandler(application_PreSendRequestHeaders);
application.PreSendRequestContent += new EventHandler(application_PreSendRequestContent);
}
private void application_BeginRequest(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_BeginRequest"); }
private void application_EndRequest(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_EndRequest"); }
private void application_PreRequestHandlerExecute(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_PreRequestHandlerExecute"); }
private void application_PostRequestHandlerExecute(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_PostRequestHandlerExecute"); }
private void application_ReleaseRequestState(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_ReleaseRequestState"); }
private void application_AcquireRequestState(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_AcquireRequestState"); }
private void application_PreSendRequestContent(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_PreSendRequestContent"); }
private void application_PreSendRequestHeaders(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_PreSendRequestHeaders"); }
private void application_ResolveRequestCache(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_ResolveRequestCache"); }
private void application_AuthorizeRequest(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_AuthorizeRequest"); }
private void application_AuthenticateRequest(object sender, EventArgs e)
{ HttpApplication application = (HttpApplication)sender;
application.Context.Response.Write("application_AuthenticateRequest"); }
}
}
HttpModule1和HttpModule2模仿ValidaterHttpModuleEvents编写（除了类名改变外，事件和方法不变），不贴代码了。运行结果如下：
从运行结果可以看到，在web.config文件中引入自定义HttpModule的顺序就决定了多个自定义HttpModule在处理一个HTTP请求的接管顺序。
(3)、利用HttpModule实现终止此次HttpRequest请求
在BeginRequest事件中，使用HttpApplication.CompleteRequest()方法可以实现当满足一定条件时终止此次HttpRequest请求
using System;
using System.Web;
namespace ClassLibrary1
{ public class MyHttpModule : IHttpModule
{ public void Dispose() { } public void Init(HttpApplication context)
{ context.BeginRequest += new EventHandler(Application_BeginRequest);
}
public void Application_BeginRequest(object sender, EventArgs e)
{ HttpApplication application = sender as HttpApplication;
application.CompleteRequest();
application.Context.Response.Write("请求被终止"); }
}
}
说明：
a、对于一个HttpModule，在BeginRquest中终止，但是仍然会调用EndRequest事件，以及PreSendRequestHeaders事件和PreSendRequestContent事件。也可以说是直接跳转到EndRequest事件，而不会调用这期间的事件 b、如果有两个HttpModule，在第一个HttpModule的BeginRequest中终止，仅仅不会调用第二个HttpModule的BeginRequest，但仍然会调用两个EndRequest事件，以及PreSendRequestHeaders事件和PreSendRequestContent事件。看下面的图示：
出处：http://www.cnblogs.com/humble/p/3913078.html