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HTTPModule生命周期与页面执行模型

2008-01-08 11:24 447 查看
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:
[align=left]using System;[/align]
[align=left]using System.Collections.Generic;[/align]
[align=left]using System.Text;[/align]
[align=left]using System.Web;[/align]
[align=left] [/align]
[align=left]namespace MyHttpModule[/align]
[align=left]{[/align]
[align=left]     ///<summary>[/align]
[align=left]     ///说明:用来实现自己的HttpModule类。[/align]
[align=left]     ///作者:文野[/align]
[align=left]     ///联系:stwyhm@cnblogs.com[/align]
[align=left]     ///</summary>[/align]
[align=left]     public class MyFirstHttpModule : IHttpModule[/align]
[align=left]     {[/align]
[align=left]         private void Application_BeginRequest(object sender, EventArgs e)[/align]
[align=left]         {[/align]
[align=left]              HttpApplication application = (HttpApplication)sender;[/align]
[align=left]              HttpContext context = application.Context;[/align]
[align=left]              HttpRequest request = application.Request;[/align]
[align=left]              HttpResponse response = application.Response;[/align]
[align=left] [/align]
[align=left]              response.Write("我来自自定义HttpModule中的BeginRequest<br />");[/align]
[align=left]         }[/align]
[align=left] [/align]
[align=left]         private void Application_EndRequest(object sender, EventArgs e)[/align]
[align=left]         {[/align]
[align=left]              HttpApplication application = (HttpApplication)sender;[/align]
[align=left]              HttpContext context = application.Context;[/align]
[align=left]              HttpRequest request = application.Request;[/align]
[align=left]              HttpResponse response = application.Response;[/align]
[align=left] [/align]
[align=left]              response.Write("我来自自定义HttpModule中的EndRequest<br />");[/align]
[align=left]         }[/align]
[align=left] [/align]
[align=left]         #region IHttpModule 成员[/align]
[align=left] [/align]
[align=left]         public void Dispose()[/align]
[align=left]         {}[/align]
[align=left] [/align]
[align=left]         public void Init(HttpApplication application)[/align]
[align=left]         {[/align]
[align=left]              application.BeginRequest += new EventHandler(Application_BeginRequest);[/align]
[align=left]              application.EndRequest += new EventHandler(Application_EndRequest);[/align]
[align=left]         }[/align]
[align=left] [/align]
[align=left]         #endregion[/align]
[align=left]     }[/align]
}
在Web.config进行如下配置
<addname="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
[align=left]using System;[/align]
[align=left]using System.Collections.Generic;[/align]
[align=left]using System.Text;[/align]
[align=left]using System.Web;[/align]
[align=left] [/align]
[align=left]namespace MyHttpModule[/align]
[align=left]{[/align]
[align=left]    public class ValidaterHttpModule : IHttpModule[/align]
[align=left]    {[/align]
[align=left]        #region IHttpModule 成员[/align]
[align=left] [/align]
[align=left]        public void Dispose()[/align]
[align=left]        {}[/align]
[align=left] [/align]
[align=left]        public void Init(HttpApplication application)[/align]
[align=left]        {[/align]
[align=left]            application.BeginRequest += new EventHandler(application_BeginRequest);[/align]
[align=left]            application.EndRequest += new EventHandler(application_EndRequest);[/align]
[align=left]            application.PreRequestHandlerExecute += new EventHandler(application_PreRequestHandlerExecute);[/align]
[align=left]            application.PostRequestHandlerExecute += new EventHandler(application_PostRequestHandlerExecute);[/align]
[align=left]            application.ReleaseRequestState += new EventHandler(application_ReleaseRequestState);[/align]
[align=left]            application.AcquireRequestState += new EventHandler(application_AcquireRequestState);[/align]
[align=left]            application.AuthenticateRequest += new EventHandler(application_AuthenticateRequest);[/align]
[align=left]            application.AuthorizeRequest += new EventHandler(application_AuthorizeRequest);[/align]
[align=left]            application.ResolveRequestCache += new EventHandler(application_ResolveRequestCache);[/align]
[align=left]            application.PreSendRequestHeaders += new EventHandler(application_PreSendRequestHeaders);[/align]
[align=left]            application.PreSendRequestContent += new EventHandler(application_PreSendRequestContent);[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_PreSendRequestContent(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]           application.Context.Response.Write("application_PreSendRequestContent<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_PreSendRequestHeaders(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.Context.Response.Write("application_PreSendRequestHeaders<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_ResolveRequestCache(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.Context.Response.Write("application_ResolveRequestCache<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_AuthorizeRequest(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.Context.Response.Write("application_AuthorizeRequest<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_AuthenticateRequest(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.Context.Response.Write("application_AuthenticateRequest<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_AcquireRequestState(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.Context.Response.Write("application_AcquireRequestState<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_ReleaseRequestState(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.Context.Response.Write("application_ReleaseRequestState<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_PostRequestHandlerExecute(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.Context.Response.Write("application_PostRequestHandlerExecute<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_PreRequestHandlerExecute(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.Context.Response.Write("application_PreRequestHandlerExecute<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_EndRequest(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.Context.Response.Write("application_EndRequest<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void application_BeginRequest(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.Context.Response.Write("application_BeginRequest<br/>");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        [/align]
[align=left] [/align]
[align=left]        #endregion[/align]
[align=left]    }[/align]
[align=left]}[/align]



 
多个自定义的Http Module的运作
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。注:系统默认那几个HttpModule是最先衩ASP.NET Framework所加载上去的。
示例3:(代码类同示例2)



 

HttpModule中终止此次的HTTP请求
可以利用HttpModule通过调用HttpApplication.CompleteRequest()方法实现当满足某一个条件时终止此次的HTTP请求。
需要注意的是,即使调用了HttpApplication.CompleteRequest()方法终止了一个HTTP请求,ASP.NET Framework仍然会触发HttpApplication后面的这3个事件:EndRequest事件、PreSendRequestHeaders事件、PreSendRequestContent事件。
如果存在多个自定义的HttpModule的话,当Module1终止了一个HTTP请求,这个HTTP请求将不会再触发Module2中相应的事件了,但Module2的最后三个事件仍会被触发。
示例4:
[align=left]using System;[/align]
[align=left]using System.Collections.Generic;[/align]
[align=left]using System.Text;[/align]
[align=left]using System.Web;[/align]
[align=left] [/align]
[align=left]namespace MyHttpModule[/align]
[align=left]{[/align]
[align=left]    public class CompleteRequestHttpModule : IHttpModule[/align]
[align=left]    {[/align]
[align=left]        #region IHttpModule 成员[/align]
[align=left] [/align]
[align=left]        public void Dispose()[/align]
[align=left]        {}[/align]
[align=left] [/align]
[align=left]        public void Init(HttpApplication application)[/align]
[align=left]        {[/align]
[align=left]            application.BeginRequest += new EventHandler(Application_BeginRequest);[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        void Application_BeginRequest(object sender, EventArgs e)[/align]
[align=left]        {[/align]
[align=left]            HttpApplication application = (HttpApplication)sender;[/align]
[align=left]            application.CompleteRequest();[/align]
[align=left]            application.Context.Response.Write("请求被终止。");[/align]
[align=left]        }[/align]
[align=left] [/align]
[align=left]        #endregion[/align]
[align=left]    }[/align]
[align=left]}[/align]


 
 
注意: 当存在多个Module时他们的执行顺序是与你的配置顺充有关, 配置在前的先执行. 当多个Module间存在关联关系时需要注意的.
 
代码:http://download1.csdn.net/down3/20070527/27174300529.rar

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