HttpModule,HttpHandler,HttpHandlerFactory
HttpModule:Http模块,可以在页面处理前后、应用程序初始化、出错等时候加入自己的事件处理程序.
HttpHandler:Http处理程序,处理页面请求
HttpHandlerFactory:用来创建Http处理程序,创建的同时可以附加自己的事件处理程序
一、HttpModule 这个对象我们经常用来进行统一的权限判断、日志等处理
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web.config中配置:
<add name="test" type="HttpHandle.MyModule, HttpHandle"/>
</httpModules>
二、HttpHandler 这个对象经常用来加入特殊的后缀所对应的处理程序,比如可以限制.doc的文件只能给某个权限的人访问。 Asp.Net中的Page类就是一个IHttpHandler的实现例子代码:
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web.config中配置:
<httpHandlers>
<add verb="*" path="*.aspx" type="HttpHandle.MyHandler, HttpHandle"/>
</httpHandlers>
这个对象主要就是ProcessRequest方法,在这个方法中输出版权信息,但同时也有一个问题:原来的页面不会被处理,也就是说页面中只有版权声明了。那么所有的aspx页面都不能正常运行了
三、HttpHandlerFactory 这个对象也可以用来加入特殊的后缀所对应的处理程序,它的功能比HttpHandler要更加强大,在系统的web.config中就是通过注册HttpHandlerFactory来实现aspx页面的访问的:
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HttpHandlerFactory是HttpHandler的工厂,通过它来生成不同的HttpHandler对象。 例子代码:
{
public IHttpHandler GetHandler(HttpContext context, string requestType, string url, string pathTranslated)
{
PageHandlerFactory factory = (PageHandlerFactory)Activator.CreateInstance(typeof(PageHandlerFactory), true);
IHttpHandler handler = factory.GetHandler(context, requestType, url, pathTranslated);
Execute(handler);
return handler;
}
private void Execute(IHttpHandler handler)
{
if (handler is Page)
{ //可以直接对Page对象进行操作
((Page)handler).PreLoad += new EventHandler(MyHandlerFactory_PreLoad);
}
}
void MyHandlerFactory_PreLoad(object sender, EventArgs e)
{
((Page)sender).Response.Write("Copyright @Gspring<br/>");
}
public void ReleaseHandler(IHttpHandler handler){ }
}
web.config中配置:
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<add verb="*" path="*.aspx" type="HttpHandle.MyHandlerFactory, HttpHandle"/>
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</httpHandlers>
在例子中我们通过调用系统默认的PageHandlerFactory类进行常规处理,然后在处理过程中加入自己的代码,可以在Page对象上附加自己的事件处理程序。 附一个小的恶作剧: 我们可以开发好aspx页面,然后把web应用程序发布后把所有的aspx文件的后缀都改为spring,再在web.config中加入配置:
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<add verb="*" path="*.spring" type="HttpHandle.MyHandlerFactory, HttpHandle"/>
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</httpHandlers>
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<compilation>
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<buildProviders>
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<add extension=".spring" type="System.Web.Compilation.PageBuildProvider"/>
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</buildProviders>
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</compilation>
buildProviders是用来指定spring后缀的编译程序,我们把它设置成和aspx一致就可以了。如果在IIS中发布的话还需要在应用程序配置中加入spring的后缀映射。然后我们就可以通过 http://../.../*.spring来访问我们的网站了