从上至下:执行顺序
application_BeginRequest
application_AuthenticateRequest
application_AuthorizeRequest
application_ResolveRequestCache
application_AcquireRequestState
application_PreRequestHandlerExecute
application_ReleaseRequestState
application_EndRequest
application_PreSendRequestHeaders
application_PreSendRequestContent
在web.config里
<system.web>
<httpModules>
<add type="Discuz.Forum.HttpModule, Discuz.Forum" name="HttpModule"/>
</httpModules>
</system.web>
