详解ASP.NET|详解ASP.NET MVC的整个生命周期详解ASP.NETMVC的整个生命周期

一、介绍
二、MVC生命周期详述

View的初始化和渲染呈现

三、结束

一、介绍我们做开发的，尤其是做微软技术栈的，有一个方向是跳不过去的，那就是MVC开发。我相信大家，做ASP.NET MVC 开发有的有很长时间，当然，也有刚进入这个行业的。无论如何，如果有人问你，你知道ASP.NET MVC的生命周期吗？你知道它的来世今生吗？你知道它和 ASP.NET WEBFORM 有什么区别吗?估计，这些问题，有很多人会答不上来，或者说不清楚。今天，我就把我的理解写出来，也是对我自己学习的一次回顾和总结吧。当然，由于本人能力有限，在写的过程中也可能会有一些错误，希望大家多多包涵，当然，更希望大家能不灵赐教，我们共同进步。
在开始之前，我们先来说说，ASP.NET Web Form 和 Asp.net MVC 有什么区别，这里说的区别，当然是本质区别，不是适用语法那个层次的。其实，说起来，ASP.NET WEB FORM 和 ASP.NET MVC 它们两个没有本质区别，使用的都是ASP.NET WEB FORM 的管道处理模型，ASP.NET MVC 也是通过扩展 IHttpModule 和 IHttpHandler 来实现的，都是基于 ASP.NET 的 HttpApplication 的管道处理模型扩展的，在这个层面来说，它们是一样的。当然，大家不要抬杠，我说的本质区别都是在这个方面，不同意的勿喷。
有人会问，ASP.NET MVC和 ASP.NET WEBAPI 它们会有什么不同吗？好像 WebAPi 能做的，WebMVC都可以完成，第一眼看上去，好像是这样，但是它们有着本质的不同。WebAPI 的处理管道是重新写过的，不是基于 HTTPApplication 管道扩展的。ASP.NET WEB API 类似专人做专事，它的管道处理模型更高效，并且有了 Restfull 的概念。当然，大家如何向了解更细的内容，就需要看源码了。或再说回来，到了 NET CORE 时代，二者又融合管道了。

二、MVC生命周期详述 【详解ASP.NET|详解ASP.NET MVC的整个生命周期】1、我们既然要说 ASP.NET MVC的生命周期，为了给大家一个整体印象，俗话说，文不如图，我就贴一张图，按着箭头走，相信大家也会不能理解。

文章图片

2、上图很简单，大家按着箭头走，也能理解的差不多。以下是按着我的理解，划分了4个模块。

（1）、路由模块
RouteBase 是对路由规则的抽象，也就是说，一个 RouteBase 对象，也就代表了一个条路由规则。在 ASP.NET MVC 中，有一个唯一的子类实现就是 Route ，它同样也是路由规则的代表。我们有了路由规则，一定会把这个规则存放在一个地方，这个地方保存了很多路由规则，这个地方就是 RouteCollection，中文叫“路由集合”，因为这个集合里面包含的就是 RouteBase 对象。

RouteCollection 就是路由集合，用于保存路由规则对象，它的定义形式：

[TypeForwardedFrom("System.Web.Routing, Version=3.5.0.0, Culture=Neutral, PublicKeyToken=31bf3856ad364e35")]public class RouteCollection : Collection{private class ReadLockDisposable : IDisposable{private ReaderWriterLockSlim _rwLock; public ReadLockDisposable(ReaderWriterLockSlim rwLock){this._rwLock = rwLock; }void IDisposable.Dispose(){this._rwLock.ExitReadLock(); }}......

RouteTable 就是路由表，其实它和 RouteCollection 是一样的。

public class RouteTable{private static RouteCollection _instance = new RouteCollection(); public static RouteCollection Routes{get{return RouteTable._instance; }}}

在ASP.NET MVC处理管线中的第一站就是路由模块。当请求到达路由模块后，ASP.NET MVC 框架就会根据 RouteTable 中配置的路由模板来匹配当前请求以获得对应的 Controller 和 Action 信息。具体的匹配过程就是有UrlRoutingModule(System.Web.Routing.UrlRoutingModule)来实现的。如果遇到一个匹配的规则，就会立刻跳出下面的配置。也就是说，配置过程是有顺序的，如果有一个匹配，后面就算有匹配的也不会执行的。

namespace System.Web.Routing{[TypeForwardedFrom("System.Web.Routing, Version=3.5.0.0, Culture=Neutral, PublicKeyToken=31bf3856ad364e35")]public class UrlRoutingModule : IHttpModule{private static readonly object _contextKey = new object(); private static readonly object _requestDataKey = new object(); private RouteCollection _routeCollection; public RouteCollection RouteCollection{get{if (this._routeCollection == null){this._routeCollection = RouteTable.Routes; }return this._routeCollection; }set{this._routeCollection = value; }}protected virtual void Dispose(){}protected virtual void Init(HttpApplication application){if (application.Context.Items[UrlRoutingModule._contextKey] != null){return; }application.Context.Items[UrlRoutingModule._contextKey] = UrlRoutingModule._contextKey; application.PostResolveRequestCache += new EventHandler(this.OnApplicationPostResolveRequestCache); }private void OnApplicationPostResolveRequestCache(object sender, EventArgs e){HttpApplication httpApplication = (HttpApplication)sender; HttpContextBase context = new HttpContextWrapper(httpApplication.Context); this.PostResolveRequestCache(context); }[Obsolete("This method is obsolete. Override the Init method to use the PostMapRequestHandler event.")]public virtual void PostMapRequestHandler(HttpContextBase context){}public virtual void PostResolveRequestCache(HttpContextBase context){RouteData routeData = https://www.it610.com/article/this.RouteCollection.GetRouteData(context); 第一步匹配路由规则if (routeData == null){return; }IRouteHandler routeHandler = routeData.RouteHandler; 第二步：如有匹配，就找到RouteHandler对象，该类型的实例是：MvcRouteHandler。if (routeHandler == null){throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, SR.GetString("UrlRoutingModule_NoRouteHandler"), new object[0])); }if (routeHandler is StopRoutingHandler){return; }RequestContext requestContext = new RequestContext(context, routeData); context.Request.RequestContext = requestContext; IHttpHandler httpHandler = routeHandler.GetHttpHandler(requestContext); 第三步，根据 RouteHandler 对象，找到最终处理请求的 IHttpHandler 的对象，该类型是 MvcHandlerif (httpHandler == null){throw new InvalidOperationException(string.Format(CultureInfo.CurrentUICulture, SR.GetString("UrlRoutingModule_NoHttpHandler"), new object[]{routeHandler.GetType()})); }if (!(httpHandler is UrlAuthFailureHandler)){context.RemapHandler(httpHandler); 第四步，有找到的 IHttpHandler 处理请求。return; }if (FormsAuthenticationModule.FormsAuthRequired){UrlAuthorizationModule.ReportUrlAuthorizationFailure(HttpContext.Current, this); return; }throw new HttpException(401, SR.GetString("Assess_Denied_Description3")); }void IHttpModule.Dispose(){this.Dispose(); }void IHttpModule.Init(HttpApplication application){this.Init(application); }}}

（2）、Controller 创建模块
经过了路由模块，生成了 RouteData 路由数据，它包含了根据路由规则匹配的 Controller 和 Action。有了路由数据，需要有处理器来处理请求，这个任务就交给了 RouteData 的 RouteHandler 属性，它的类型是 IRouteHandler，它的值就是MvcRouteHandler，MvcRouteHandler 调用 GetHttpHandler 获取处理请求的 IHttpHandler 对象，在 MVC 框架中就是 MvcHandler，详细代码如下：

namespace System.Web.Mvc{/// Selects the controller that will handle an HTTP request.public class MvcHandler : IHttpAsyncHandler, IHttpHandler, IRequiresSessionState{private struct ProcessRequestState{internal IAsyncController AsyncController; internal IControllerFactory Factory; internal RequestContext RequestContext; internal void ReleaseController(){this.Factory.ReleaseController(this.AsyncController); }}[CompilerGenerated][Serializable]private sealed class <>c{public static readonly MvcHandler.<>c <>9 = new MvcHandler.<>c(); public static BeginInvokeDelegate <>9__20_0; public static EndInvokeVoidDelegate <>9__20_1; public static Func <>9__26_0; internal IAsyncResult b__20_0(AsyncCallback asyncCallback, object asyncState, MvcHandler.ProcessRequestState innerState){IAsyncResult result; try{result = innerState.AsyncController.BeginExecute(innerState.RequestContext, asyncCallback, asyncState); }catch{innerState.ReleaseController(); throw; }return result; }internal void b__20_1(IAsyncResult asyncResult, MvcHandler.ProcessRequestState innerState){try{innerState.AsyncController.EndExecute(asyncResult); }finally{innerState.ReleaseController(); }}internal bool b__26_0(KeyValuePair entry){return entry.Value =https://www.it610.com/article/= UrlParameter.Optional; }}private static readonly object _processRequestTag = new object(); internal static readonly string MvcVersion = MvcHandler.GetMvcVersionString(); /// Contains the header name of the ASP.NET MVC version.public static readonly string MvcVersionHeaderName ="X-AspNetMvc-Version"; private ControllerBuilder _controllerBuilder; internal ControllerBuilder ControllerBuilder{get{if (this._controllerBuilder == null){this._controllerBuilder = ControllerBuilder.Current; }return this._controllerBuilder; }set{this._controllerBuilder = value; }}/// Gets or sets a value that indicates whether the MVC response header is disabled./// true if the MVC response header is disabled; otherwise, false.public static bool DisableMvcResponseHeader{get; set; }/// Gets a value that indicates whether another request can use theinstance./// true if theinstance is reusable; otherwise, false.protected virtual bool IsReusable{get{return false; }}/// Gets the request context./// The request context.public RequestContext RequestContext{get; private set; }/// Gets a value that indicates whether another request can use theinstance./// true if theinstance is reusable; otherwise, false.bool IHttpHandler.IsReusable{get{return this.IsReusable; }}/// Initializes a new instance of theclass./// The request context./// The parameter is null.public MvcHandler(RequestContext requestContext){if (requestContext == null){throw new ArgumentNullException("requestContext"); }this.RequestContext = requestContext; }/// Adds the version header by using the specified HTTP context./// The HTTP context.protected internal virtual void AddVersionHeader(HttpContextBase httpContext){if (!MvcHandler.DisableMvcResponseHeader){httpContext.Response.AppendHeader(MvcHandler.MvcVersionHeaderName, MvcHandler.MvcVersion); }}/// Called by ASP.NET to begin asynchronous request processing./// The status of the asynchronous call./// The HTTP context./// The asynchronous callback method./// The state of the asynchronous object.protected virtual IAsyncResult BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, object state){HttpContextBase httpContext2 = new HttpContextWrapper(httpContext); return this.BeginProcessRequest(httpContext2, callback, state); }/// Called by ASP.NET to begin asynchronous request processing using the base HTTP context./// The status of the asynchronous call./// The HTTP context./// The asynchronous callback method./// The state of the asynchronous object.protected internal virtual IAsyncResult BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, object state){IController controller; IControllerFactory factory; this.ProcessRequestInit(httpContext, out controller, out factory); IAsyncController asyncController = controller as IAsyncController; if (asyncController != null){BeginInvokeDelegate arg_51_0; if ((arg_51_0 = MvcHandler.<>c.<>9__20_0) == null){arg_51_0 = (MvcHandler.<>c.<>9__20_0 = new BeginInvokeDelegate(MvcHandler.<>c.<>9.b__20_0)); }BeginInvokeDelegate beginDelegate = arg_51_0; EndInvokeVoidDelegate arg_71_0; if ((arg_71_0 = MvcHandler.<>c.<>9__20_1) == null){arg_71_0 = (MvcHandler.<>c.<>9__20_1 = new EndInvokeVoidDelegate(MvcHandler.<>c.<>9.b__20_1)); }EndInvokeVoidDelegate endDelegate = arg_71_0; MvcHandler.ProcessRequestState invokeState = new MvcHandler.ProcessRequestState{AsyncController = asyncController,Factory = factory,RequestContext = this.RequestContext}; SynchronizationContext synchronizationContext = SynchronizationContextUtil.GetSynchronizationContext(); return AsyncResultWrapper.Begin(callback, state, beginDelegate, endDelegate, invokeState, MvcHandler._processRequestTag, -1, synchronizationContext); }Action action = delegate{try{controller.Execute(this.RequestContext); }finally{factory.ReleaseController(controller); }}; return AsyncResultWrapper.BeginSynchronous(callback, state, action, MvcHandler._processRequestTag); }/// Called by ASP.NET when asynchronous request processing has ended./// The asynchronous result.protected internal virtual void EndProcessRequest(IAsyncResult asyncResult){AsyncResultWrapper.End(asyncResult, MvcHandler._processRequestTag); }private static string GetMvcVersionString(){return new AssemblyName(typeof(MvcHandler).Assembly.FullName).Version.ToString(2); }/// Processes the request by using the specified HTTP request context./// The HTTP context.protected virtual void ProcessRequest(HttpContext httpContext){HttpContextBase httpContext2 = new HttpContextWrapper(httpContext); this.ProcessRequest(httpContext2); }/// Processes the request by using the specified base HTTP request context./// The HTTP context.protected internal virtual void ProcessRequest(HttpContextBase httpContext){IController controller; IControllerFactory controllerFactory; this.ProcessRequestInit(httpContext, out controller, out controllerFactory); try{controller.Execute(this.RequestContext); }finally{controllerFactory.ReleaseController(controller); }}private void ProcessRequestInit(HttpContextBase httpContext, out IController controller, out IControllerFactory factory){HttpContext current = HttpContext.Current; if (current != null){bool? flag = ValidationUtility.IsValidationEnabled(current); bool flag2 = true; if (flag.GetValueOrDefault() == flag2 & flag.HasValue){ValidationUtility.EnableDynamicValidation(current); }}this.AddVersionHeader(httpContext); this.RemoveOptionalRoutingParameters(); string requiredString = this.RequestContext.RouteData.GetRequiredString("controller"); factory = this.ControllerBuilder.GetControllerFactory(); controller = factory.CreateController(this.RequestContext, requiredString); if (controller == null){throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, MvcResources.ControllerBuilder_FactoryReturnedNull, new object[]{factory.GetType(),requiredString})); }}private void RemoveOptionalRoutingParameters(){IDictionary arg_2F_0 = this.RequestContext.RouteData.Values; Func arg_2F_1; if ((arg_2F_1 = MvcHandler.<>c.<>9__26_0) == null){arg_2F_1 = (MvcHandler.<>c.<>9__26_0 = new Func(MvcHandler.<>c.<>9.b__26_0)); }arg_2F_0.RemoveFromDictionary(arg_2F_1); }/// Enables processing of HTTP Web requests by a custom HTTP handler that implements theinterface./// Anobject that provides references to the intrinsic server objects (for example, Request, Response, Session, and Server) that are used to service HTTP requests.void IHttpHandler.ProcessRequest(HttpContext httpContext){this.ProcessRequest(httpContext); }/// Called by ASP.NET to begin asynchronous request processing using the base HTTP context./// The status of the asynchronous call./// The HTTP context./// The asynchronous callback method./// The data.IAsyncResult IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData){return this.BeginProcessRequest(context, cb, extraData); }/// Called by ASP.NET when asynchronous request processing has ended./// The asynchronous result.void IHttpAsyncHandler.EndProcessRequest(IAsyncResult result){this.EndProcessRequest(result); }}}HttpRuntime 调用 IHttpHandler 类型的调用 ProcessRequest() 方法，用于处理请求。protected internal virtual void ProcessRequest(HttpContextBase httpContext){IController controller; IControllerFactory controllerFactory; this.ProcessRequestInit(httpContext, out controller, out controllerFactory); 创建 IControllerFactory，并创建 IController 对象。try{controller.Execute(this.RequestContext); 执行Controller，背后就是调用相应的 Action 方法。}finally{controllerFactory.ReleaseController(controller); }}

核心处理请求的方法是ProcessRequestInit()，用于创建 IController 和 IControllerFactory 实例。IControllerFactory 的实际类型是：DefaultControllerFactory，该类型用于创建 IController类型的实例。

private void ProcessRequestInit(HttpContextBase httpContext, out IController controller, out IControllerFactory factory){HttpContext current = HttpContext.Current; if (current != null){bool? flag = ValidationUtility.IsValidationEnabled(current); bool flag2 = true; if (flag.GetValueOrDefault() == flag2 & flag.HasValue){ValidationUtility.EnableDynamicValidation(current); }}this.AddVersionHeader(httpContext); this.RemoveOptionalRoutingParameters(); string requiredString = this.RequestContext.RouteData.GetRequiredString("controller"); factory = this.ControllerBuilder.GetControllerFactory(); controller = factory.CreateController(this.RequestContext, requiredString); if (controller == null){throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, MvcResources.ControllerBuilder_FactoryReturnedNull, new object[]{factory.GetType(),requiredString})); }}

以上加红的代码就是创建 IController 的实例的逻辑。IController 实例创建完成后，判断是否实现了 IAsyncController 接口，如果是，就异步执行 Controller 方法的调用，否则就同步执行。

protected internal virtual IAsyncResult BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, object state){IController controller; IControllerFactory factory; this.ProcessRequestInit(httpContext, out controller, out factory); IAsyncController asyncController = controller as IAsyncController; 判读是否是需要异步执行if (asyncController != null)异步执行{BeginInvokeDelegate arg_51_0; if ((arg_51_0 = MvcHandler.<>c.<>9__20_0) == null){arg_51_0 = (MvcHandler.<>c.<>9__20_0 = new BeginInvokeDelegate(MvcHandler.<>c.<>9.b__20_0)); }BeginInvokeDelegate beginDelegate = arg_51_0; EndInvokeVoidDelegate arg_71_0; if ((arg_71_0 = MvcHandler.<>c.<>9__20_1) == null){arg_71_0 = (MvcHandler.<>c.<>9__20_1 = new EndInvokeVoidDelegate(MvcHandler.<>c.<>9.b__20_1)); }EndInvokeVoidDelegate endDelegate = arg_71_0; MvcHandler.ProcessRequestState invokeState = new MvcHandler.ProcessRequestState{AsyncController = asyncController,Factory = factory,RequestContext = this.RequestContext}; SynchronizationContext synchronizationContext = SynchronizationContextUtil.GetSynchronizationContext(); return AsyncResultWrapper.Begin(callback, state, beginDelegate, endDelegate, invokeState, MvcHandler._processRequestTag, -1, synchronizationContext); }Action action = delegate//同步执行。{try{controller.Execute(this.RequestContext); }finally{factory.ReleaseController(controller); }}; return AsyncResultWrapper.BeginSynchronous(callback, state, action, MvcHandler._processRequestTag); }

（3）、Action 执行模块，通过 ControllerActionInvoker 调用 InvokeAction() 执行其方法。Action 方法的执行也有2个版本，一个是异步版本，一个是同步版本。由于 ActionInvoker 实现了 IAsyncActionInvoker 接口，所以也是以已方式执行。该类型是 AsyncControllerActionInvoker。
A、当Controller对象被创建之后，紧接着就会执行Controler 对象的 Execute()，其实背后就是调用 InvokeAction() 方法：

public virtual bool InvokeAction(ControllerContext controllerContext, string actionName){if (controllerContext == null){throw new ArgumentNullException("controllerContext"); }if (string.IsNullOrEmpty(actionName) && !controllerContext.RouteData.HasDirectRouteMatch()){throw new ArgumentException(MvcResources.Common_NullOrEmpty, "actionName"); }ControllerDescriptor controllerDescriptor = this.GetControllerDescriptor(controllerContext); ActionDescriptor actionDescriptor = this.FindAction(controllerContext, controllerDescriptor, actionName); if (actionDescriptor != null){FilterInfo filters = this.GetFilters(controllerContext, actionDescriptor); 获取所有过滤器，全局的、控制器的和方法的try{AuthenticationContext authenticationContext = this.InvokeAuthenticationFilters(controllerContext, filters.AuthenticationFilters, actionDescriptor); 认证过滤器的执行。if (authenticationContext.Result != null){AuthenticationChallengeContext authenticationChallengeContext = this.InvokeAuthenticationFiltersChallenge(controllerContext, filters.AuthenticationFilters, actionDescriptor, authenticationContext.Result); this.InvokeActionResult(controllerContext, authenticationChallengeContext.Result ?? authenticationContext.Result); }else{AuthorizationContext authorizationContext = this.InvokeAuthorizationFilters(controllerContext, filters.AuthorizationFilters, actionDescriptor); 授权过滤器的执行。if (authorizationContext.Result != null){AuthenticationChallengeContext authenticationChallengeContext2 = this.InvokeAuthenticationFiltersChallenge(controllerContext, filters.AuthenticationFilters, actionDescriptor, authorizationContext.Result); this.InvokeActionResult(controllerContext, authenticationChallengeContext2.Result ?? authorizationContext.Result); }else{if (controllerContext.Controller.ValidateRequest){ControllerActionInvoker.ValidateRequest(controllerContext); }IDictionary parameterValues = this.GetParameterValues(controllerContext, actionDescriptor); 获取方法执行参数。ActionExecutedContext actionExecutedContext = this.InvokeActionMethodWithFilters(controllerContext, filters.ActionFilters, actionDescriptor, parameterValues); 执行action，同时执行执行方法前后的 IAcctionFilterAuthenticationChallengeContext authenticationChallengeContext3 = this.InvokeAuthenticationFiltersChallenge(controllerContext, filters.AuthenticationFilters, actionDescriptor, actionExecutedContext.Result); this.InvokeActionResultWithFilters(controllerContext, filters.ResultFilters, authenticationChallengeContext3.Result ?? actionExecutedContext.Result); 执行 ActionResult，同时执行方法前后的 IResultFilter}}}catch (ThreadAbortException){throw; }catch (Exception exception){ExceptionContext exceptionContext = this.InvokeExceptionFilters(controllerContext, filters.ExceptionFilters, exception); if (!exceptionContext.ExceptionHandled){throw; }this.InvokeActionResult(controllerContext, exceptionContext.Result); //异常过滤器的执行。}return true; }return false; }

B、当选择完合适的Action后，接着就是 ModelBinder（默认是System.Web.Mvc.DefaultModelBinder），它会从http请求的参数中提取数据并实现类型转换，数据校验（例如是否必填，数据格式等）以及是否自动装配到action方法的参数中System.Web.Mvc.DefaultModelBinder

protected virtual IDictionary GetParameterValues(ControllerContext controllerContext, ActionDescriptor actionDescriptor){Dictionary dictionary = new Dictionary(StringComparer.OrdinalIgnoreCase); ParameterDescriptor[] parameters = actionDescriptor.GetParameters(); for (int i = 0; i < parameters.Length; i++){ParameterDescriptor parameterDescriptor = parameters[i]; dictionary[parameterDescriptor.ParameterName] = this.GetParameterValue(controllerContext, parameterDescriptor); }return dictionary; }protected virtual object GetParameterValue(ControllerContext controllerContext, ParameterDescriptor parameterDescriptor){Type parameterType = parameterDescriptor.ParameterType; IModelBinder arg_92_0 = this.GetModelBinder(parameterDescriptor); IValueProvider valueProvider = controllerContext.Controller.ValueProvider; string modelName = parameterDescriptor.BindingInfo.Prefix ?? parameterDescriptor.ParameterName; Predicate propertyFilter = ControllerActionInvoker.GetPropertyFilter(parameterDescriptor); ModelBindingContext bindingContext = new ModelBindingContext{FallbackToEmptyPrefix = parameterDescriptor.BindingInfo.Prefix == null,ModelMetadata = https://www.it610.com/article/ModelMetadataProviders.Current.GetMetadataForType(null, parameterType),ModelName = modelName,ModelState = controllerContext.Controller.ViewData.ModelState,PropertyFilter = propertyFilter,ValueProvider = valueProvider}; return arg_92_0.BindModel(controllerContext, bindingContext) ?? parameterDescriptor.DefaultValue; }

C、Authentication Filter是mvc5中新增的一个Filter，它会先于authorization filter执行，目的是对访问用户的认证。在MVC5之前，认证和授权都是通过authorization filter来实现的，但现在这2个操作就分开来了，各自管各自喽。

AuthenticationContext authenticationContext = this.InvokeAuthenticationFilters(controllerContext, filters.AuthenticationFilters, actionDescriptor); if (authenticationContext.Result != null){AuthenticationChallengeContext authenticationChallengeContext = this.InvokeAuthenticationFiltersChallenge(controllerContext, filters.AuthenticationFilters, actionDescriptor, authenticationContext.Result); this.InvokeActionResult(controllerContext, authenticationChallengeContext.Result ?? authenticationContext.Result); }

D、Action filters有2个方法OnActionExecuting和OnActionExecuted分别在action执行前后执行。我们也可以通过实现IActionFilter接口来实现你个性化的过滤机制

protected virtual ActionExecutedContext InvokeActionMethodWithFilters(ControllerContext controllerContext, IList filters, ActionDescriptor actionDescriptor, IDictionary parameters){ActionExecutingContext preContext = new ActionExecutingContext(controllerContext, actionDescriptor, parameters); Func seed = () => new ActionExecutedContext(controllerContext, actionDescriptor, false, null){Result = this.InvokeActionMethod(controllerContext, actionDescriptor, parameters)}; return filters.Reverse().Aggregate(seed, (Func next, IActionFilter filter) => () => ControllerActionInvoker.InvokeActionMethodFilter(filter, preContext, next))(); }

E、接下来就是执行我们平时在Action方法中写的代码了（根据请求相应结果）

protected virtual ActionResult InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary parameters){object actionReturnValue = https://www.it610.com/article/actionDescriptor.Execute(controllerContext, parameters); return this.CreateActionResult(controllerContext, actionDescriptor, actionReturnValue); }

（4）、ActionResult 执行模块。
A、在 ActionResult 执行前后，仍然会有一个filter（IResultFilter），同样的，通过实现 IResultFilter 接口你可以定制自己的过滤逻辑。

namespace System.Web.Mvc{/// Defines the methods that are required for a result filter.public interface IResultFilter{/// Called before an action result executes./// The filter context.void OnResultExecuting(ResultExecutingContext filterContext); /// Called after an action result executes./// The filter context.void OnResultExecuted(ResultExecutedContext filterContext); }}

B、ActionResult 就是把处理的用户请求结果返回。因此 ViewResult, PartialViewResult, RedirectToRouteResult, RedirectResult, ContentResult, JsonResult, FileResult and EmptyResult就是具体的返回类型。
C、上面的返回类型可以大致分为2类：ViewResult 和非ViewResult。对于需要生成html页面给客户端的划到ViewResult，而其他的例如返回文本，json数据等则划分到非ViewResult，对于非ViewResult直接返回就可以了。

View的初始化和渲染呈现
A、对于 ViewResult 最终是由合适的 View Engine 通过调用 IView 的 Render() 方法来渲染的：

namespace System.Web.Mvc{/// Defines the methods that are required for a view engine.public interface IViewEngine{/// Finds the specified partial view by using the specified controller context./// The partial view./// The controller context./// The name of the partial view./// true to specify that the view engine returns the cached view, if a cached view exists; otherwise, false.ViewEngineResult FindPartialView(ControllerContext controllerContext, string partialViewName, bool useCache); /// Finds the specified view by using the specified controller context./// The page view./// The controller context./// The name of the view./// The name of the master./// true to specify that the view engine returns the cached view, if a cached view exists; otherwise, false.ViewEngineResult FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache); /// Releases the specified view by using the specified controller context./// The controller context./// The view.void ReleaseView(ControllerContext controllerContext, IView view); }}

namespace System.Web.Mvc{/// Defines the methods that are required for a view.public interface IView{/// Renders the specified view context by using the specified the writer object./// The view context./// The writer object.void Render(ViewContext viewContext, TextWriter writer); }}

B、整个处理过程是由 IViewEngine 来实现的。ASP.NET MVC 默认提供 WebForm（.aspx）和 Razor(.cshtml) 模板引擎，你可以通过实现 IViewEngine 接口来实现自己的 ViewEngine，然后在Application_Start方法中做如下注册：

protected void Application_Start(){ //移除所有的View引擎包括Webform和Razor ViewEngines.Engines.Clear(); //注册你自己的View引擎 ViewEngines.Engines.Add(new CustomViewEngine()); }

C、最后，Html Helpers将帮我们生成 input 标签，基于AJAX的 form 等等。
（5）、作为总结，将每个节点主要的代码类贴出来。
这就是整个流程的代码节点，有些是同步执行，有些是异步执行，把握关键点，我这里只是谢了一个大概。

UrlRoutingModule-----RouteCollection.GetRouteData(context)----->IRouteHandler routeHandler = routeData.RouteHandler------》IHttpHandler httpHandler = routeHandler.GetHttpHandler(requestContext)-----》context.RemapHandler(httpHandler)------->MvcHandler------->ProcessRequest()------>ProcessRequestInit()--------》IController------>controller.Execute(this.RequestContext)-------->ControllerActionInvoker------->InvoleAction()--------->InvoleActionMethod()------->InvoleActionReslt()

三、结束今天就到这里了，东西虽然不多，但是也写了2个多小时。今天就算自己有学习了一边，大家一定要好好的把握这个流程，对于解决程序中的问题，扩展框架都有很大的好处。我们作为程序员的，应该要知道其一，也要知道其二。没事，看看源码，我们对框架和我们自己的代码有更深的了解。当然，这样做也是有代价的，需要更多的时间去支持，我相信我们的付出是值得。不忘初心，继续努力。老天不会辜负努力的人。
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