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<MvcHandler.ProcessRequestState> arg_51_0; if ((arg_51_0 = MvcHandler.<>c.<>9__20_0) == null) { arg_51_0 = (MvcHandler.<>c.<>9__20_0 = new BeginInvokeDelegate<MvcHandler.ProcessRequestState>(MvcHandler.<>c.<>9.<BeginProcessRequest>b__20_0)); } BeginInvokeDelegate<MvcHandler.ProcessRequestState> beginDelegate = arg_51_0; EndInvokeVoidDelegate<MvcHandler.ProcessRequestState> arg_71_0; if ((arg_71_0 = MvcHandler.<>c.<>9__20_1) == null) { arg_71_0 = (MvcHandler.<>c.<>9__20_1 = new EndInvokeVoidDelegate<MvcHandler.ProcessRequestState>(MvcHandler.<>c.<>9.<BeginProcessRequest>b__20_1)); } EndInvokeVoidDelegate<MvcHandler.ProcessRequestState> endDelegate = arg_71_0; MvcHandler.ProcessRequestState invokeState = new MvcHandler.ProcessRequestState { AsyncController = asyncController, Factory = factory, RequestContext = this.RequestContext }; SynchronizationContext synchronizationContext = SynchronizationContextUtil.GetSynchronizationContext(); return AsyncResultWrapper.Begin<MvcHandler.ProcessRequestState>(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<string, object> 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 IAcctionFilter AuthenticationChallengeContext 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; }