关于IHttpModule的相关知识总结

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

<system.web>

<httpModules>

<add name="..."  type="MyApplication.RequestDurationLoggerModule, MyApplication"/>

</httpModules>

</system.web>

2)IIS7注册HttpModule

<system.webServer>

<modules>

   <add name="..."    type="MyApplication.RequestDurationLoggerModule, MyApplication"/>

</modules>

</system.webServer>

​

 

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()

{ }

/// <summary>

/// 验证HttpModule事件机制

/// </summary>

/// <param name="application"></param>

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<br/>");

}

private void application_EndRequest(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_EndRequest<br/>");

}

private void application_PreRequestHandlerExecute(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_PreRequestHandlerExecute<br/>");

}

private void application_PostRequestHandlerExecute(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_PostRequestHandlerExecute<br/>");

}

private void application_ReleaseRequestState(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_ReleaseRequestState<br/>");

}

private void application_AcquireRequestState(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_AcquireRequestState<br/>");

}

private void application_PreSendRequestContent(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_PreSendRequestContent<br/>");

}

private void application_PreSendRequestHeaders(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_PreSendRequestHeaders<br/>");

}

private void application_ResolveRequestCache(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_ResolveRequestCache<br/>");

}

private void application_AuthorizeRequest(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_AuthorizeRequest<br/>");

}

private void application_AuthenticateRequest(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_AuthenticateRequest<br/>");

}

}

}

 

<add name="HttpModule1" type="MyHttpModule.HttpModule1,MyHttpModule"/>

<add name="HttpModule2" type="MyHttpModule.HttpModule2,MyHttpModule"/>

 

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：

​​​​

 

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

<system.web>

<httpModules>

<add name="..."  type="MyApplication.RequestDurationLoggerModule, MyApplication"/>

</httpModules>

</system.web>

2)IIS7注册HttpModule

<system.webServer>

<modules>

   <add name="..."    type="MyApplication.RequestDurationLoggerModule, MyApplication"/>

</modules>

</system.webServer>

​

 

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()

{ }

/// <summary>

/// 验证HttpModule事件机制

/// </summary>

/// <param name="application"></param>

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<br/>");

}

private void application_EndRequest(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_EndRequest<br/>");

}

private void application_PreRequestHandlerExecute(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_PreRequestHandlerExecute<br/>");

}

private void application_PostRequestHandlerExecute(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_PostRequestHandlerExecute<br/>");

}

private void application_ReleaseRequestState(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_ReleaseRequestState<br/>");

}

private void application_AcquireRequestState(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_AcquireRequestState<br/>");

}

private void application_PreSendRequestContent(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_PreSendRequestContent<br/>");

}

private void application_PreSendRequestHeaders(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_PreSendRequestHeaders<br/>");

}

private void application_ResolveRequestCache(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_ResolveRequestCache<br/>");

}

private void application_AuthorizeRequest(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_AuthorizeRequest<br/>");

}

private void application_AuthenticateRequest(object sender, EventArgs e)

{

HttpApplication application = (HttpApplication)sender;

application.Context.Response.Write("application_AuthenticateRequest<br/>");

}

}

}

 

<add name="HttpModule1" type="MyHttpModule.HttpModule1,MyHttpModule"/>

<add name="HttpModule2" type="MyHttpModule.HttpModule2,MyHttpModule"/>

 

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：

​​​​