public interface IHttpModule
{
    // Methods
    void Dispose();
    void Init(HttpApplication context);
}

 

 

public interface IHttpHandler
{
    // Methods
    void ProcessRequest(HttpContext context);

    // Properties
    bool IsReusable { get; }
}

 

        <httpModules>
            <add name="OutputCache" type="System.Web.Caching.OutputCacheModule" />
            <add name="Session" type="System.Web.SessionState.SessionStateModule" />
            <add name="WindowsAuthentication" type="System.Web.Security.WindowsAuthenticationModule" />
            <add name="FormsAuthentication" type="System.Web.Security.FormsAuthenticationModule" />
            <add name="PassportAuthentication" type="System.Web.Security.PassportAuthenticationModule" />
            <add name="RoleManager" type="System.Web.Security.RoleManagerModule" />
            <add name="UrlAuthorization" type="System.Web.Security.UrlAuthorizationModule" />
            <add name="FileAuthorization" type="System.Web.Security.FileAuthorizationModule" />
            <add name="AnonymousIdentification" type="System.Web.Security.AnonymousIdentificationModule" />
            <add name="Profile" type="System.Web.Profile.ProfileModule" />
            <add name="ErrorHandlerModule" type="System.Web.Mobile.ErrorHandlerModule, System.Web.Mobile, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
            <add name="ServiceModel" type="System.ServiceModel.Activation.HttpModule, System.ServiceModel.Activation, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
            <add name="UrlRoutingModule-4.0" type="System.Web.Routing.UrlRoutingModule" />
            <add name="ScriptModule-4.0" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
        </httpModules>

[TypeForwardedFrom("System.Web.Routing, Version=3.5.0.0, Culture=Neutral, PublicKeyToken=31bf3856ad364e35")]
public class UrlRoutingModule : IHttpModule
{
    // Fields
    private static readonly object _contextKey = new object();
    private static readonly object _requestDataKey = new object();
    private RouteCollection _routeCollection;

    // Methods
    protected virtual void Dispose()
    {
    }

    protected virtual void Init(HttpApplication application)
    {
        if (application.Context.Items[_contextKey] == null)
        {
            application.Context.Items[_contextKey] = _contextKey;
            application.PostResolveRequestCache += new EventHandler(this.OnApplicationPostResolveRequestCache);
        }
    }

    private void OnApplicationPostResolveRequestCache(object sender, EventArgs e)
    {
        HttpApplication application = (HttpApplication) sender;
        HttpContextBase context = new HttpContextWrapper(application.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 = this.RouteCollection.GetRouteData(context);
        if (routeData != null)
        {
            IRouteHandler routeHandler = routeData.RouteHandler;
            if (routeHandler == null)
            {
                throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, SR.GetString("UrlRoutingModule_NoRouteHandler"), new object[0]));
            }
            if (!(routeHandler is StopRoutingHandler))
            {
                RequestContext requestContext = new RequestContext(context, routeData);
                context.Request.RequestContext = requestContext;
                IHttpHandler httpHandler = routeHandler.GetHttpHandler(requestContext);
                if (httpHandler == null)
                {
                    throw new InvalidOperationException(string.Format(CultureInfo.CurrentUICulture, SR.GetString("UrlRoutingModule_NoHttpHandler"), new object[] { routeHandler.GetType() }));
                }
                if (httpHandler is UrlAuthFailureHandler)
                {
                    if (!FormsAuthenticationModule.FormsAuthRequired)
                    {
                        throw new HttpException(0x191, SR.GetString("Assess_Denied_Description3"));
                    }
                    UrlAuthorizationModule.ReportUrlAuthorizationFailure(HttpContext.Current, this);
                }
                else
                {
                    context.RemapHandler(httpHandler);
                }
            }
        }
    }

    [TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")]
    void IHttpModule.Dispose()
    {
        this.Dispose();
    }

    [TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")]
    void IHttpModule.Init(HttpApplication application)
    {
        this.Init(application);
    }

    // Properties
    public RouteCollection RouteCollection
    {
        get
        {
            if (this._routeCollection == null)
            {
                this._routeCollection = RouteTable.Routes;
            }
            return this._routeCollection;
        }
        [TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")]
        set
        {
            this._routeCollection = value;
        }
    }
}

 1 public virtual void PostResolveRequestCache(HttpContextBase context)
 2 {
 3     // 通过RouteCollection的静态方法GetRouteData获取到封装路由信息的RouteData实例
 4     RouteData routeData = this.RouteCollection.GetRouteData(context);
 5     if (routeData != null)
 6     {
 7         // 再从RouteData中获取MVCRouteHandler
 8         IRouteHandler routeHandler = routeData.RouteHandler;
 9         ......
10         if (!(routeHandler is StopRoutingHandler))
11         {
12             ......
13             // 调用 IRouteHandler.GetHttpHandler()，获取的IHttpHandler 类型实例，它是由 IRouteHandler.GetHttpHandler获取的，这个得去MVC的源码里看
14             IHttpHandler httpHandler = routeHandler.GetHttpHandler(requestContext);
15             ......
16             // 合适条件下，把之前将获取的IHttpHandler 类型实例 映射到IIS HTTP处理管道中
17             context.RemapHandler(httpHandler);
18         }
19     }
20 }

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Web;
 5 using System.Web.Mvc;
 6 using System.Web.Routing;
 7 
 8 namespace ApiDemo
 9 {
10     public class RouteConfig
11     {
12         public static void RegisterRoutes(RouteCollection routes)
13         {
14             routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
15 
16             routes.MapRoute(
17                 name: "Default",
18                 url: "{controller}/{action}/{id}",
19                 defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
20             );
21         }
22     }
23 }

public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {

            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
        }
    }

    public class RouteConfig
    {
        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
System.Web.Mvc.RouteCollectionExtensions
            routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
            );
        }
    }    

 1 public static Route MapRoute(this RouteCollection routes, string name, string url, object defaults, object constraints, string[] namespaces) 
 2         {
 3             ......
 4 
 5             Route route = new Route(url, new MvcRouteHandler())             {
 6                 Defaults = new RouteValueDictionary(defaults),
 7                 Constraints = new RouteValueDictionary(constraints),
 8                 DataTokens = new RouteValueDictionary()
 9             };
10             ......
11             return route;
12         }

namespace System.Web.Routing
{  
    public interface IRouteHandler
    {       
        IHttpHandler GetHttpHandler(RequestContext requestContext);
    }
}

 1 public class MvcRouteHandler : IRouteHandler
 2 {
 3     // Fields
 4     private IControllerFactory _controllerFactory;
 5 
 6     // Methods
 7     public MvcRouteHandler()
 8     {
 9     }
10 
11     public MvcRouteHandler(IControllerFactory controllerFactory)
12     {
13         this._controllerFactory = controllerFactory;
14     }
15 
16     protected virtual IHttpHandler GetHttpHandler(RequestContext requestContext)
17     {
18         requestContext.HttpContext.SetSessionStateBehavior(this.GetSessionStateBehavior(requestContext));
19         return new MvcHandler(requestContext);
20     }
21 
22     protected virtual SessionStateBehavior GetSessionStateBehavior(RequestContext requestContext)
23     {
24         string str = (string) requestContext.RouteData.Values["controller"];
25         if (string.IsNullOrWhiteSpace(str))
26         {
27             throw new InvalidOperationException(MvcResources.MvcRouteHandler_RouteValuesHasNoController);
28         }
29         IControllerFactory factory = this._controllerFactory ?? ControllerBuilder.Current.GetControllerFactory();
30         return factory.GetControllerSessionBehavior(requestContext, str);
31     }
32 
33     IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext)
34     {
35         return this.GetHttpHandler(requestContext);
36     }
37 }
38 
39  

 1 // Copyright (c) Microsoft Open Technologies, Inc.<pre>// All rights reserved. See License.txt in the project root for license information.
 2 void IHttpHandler.ProcessRequest(HttpContext httpContext) 
 3 {
 4     ProcessRequest(httpContext);
 5 }
 6 protected virtual void ProcessRequest(HttpContext httpContext) 
 7 {
 8     HttpContextBase iHttpContext = new HttpContextWrapper(httpContext);
 9                 ProcessRequest(iHttpContext);
10 }
11 protected internal virtual void ProcessRequest(HttpContextBase httpContext) {
12     SecurityUtil.ProcessInApplicationTrust(() => {
13         IController controller;
14         IControllerFactory factory;
15         ProcessRequestInit(httpContext, out controller, out factory);
16     try
17     {
18         controller.Execute(RequestContext);
19     }
20     finally
21     {
22         factory.ReleaseController(controller);
23     }
24     });
25 }

 1 private void ProcessRequestInit(HttpContextBase httpContext, 
 2              out IController controller, out IControllerFactory factory) {
 3     // If request validation has already been enabled, make it lazy.
 4     // This allows attributes like [HttpPost] (which looks
 5     // at Request.Form) to work correctly without triggering full validation.
 6     bool? isRequestValidationEnabled = 
 7        ValidationUtility.IsValidationEnabled(HttpContext.Current);
 8     if (isRequestValidationEnabled == true) {
 9         ValidationUtility.EnableDynamicValidation(HttpContext.Current);
10     }
11     AddVersionHeader(httpContext);
12     RemoveOptionalRoutingParameters();
13     // Get the controller type
14     string controllerName = RequestContext.RouteData.GetRequiredString("controller");
15     // Instantiate the controller and call Execute
16     factory = ControllerBuilder.GetControllerFactory();
17     controller = factory.CreateController(RequestContext, controllerName);
18     if (controller == null) {
19         throw new InvalidOperationException(
20         String.Format(
21             CultureInfo.CurrentCulture,
22             MvcResources.ControllerBuilder_FactoryReturnedNull,
23             factory.GetType(),
24             controllerName));
25     }
26 }

 1 public abstract class ControllerBase : IController
 2 {
 3     protected virtual void Execute(RequestContext requestContext)
 4     {
 5         if (requestContext == null)
 6         {
 7             throw new ArgumentNullException("requestContext");
 8         }
 9         if (requestContext.HttpContext == null)
10         {
11             throw new ArgumentException(
12               MvcResources.ControllerBase_CannotExecuteWithNullHttpContext, 
13               "requestContext");
14         }
15         VerifyExecuteCalledOnce();
16         Initialize(requestContext);
17         using (ScopeStorage.CreateTransientScope())
18         {
19             ExecuteCore();
20         }
21     }
22     protected abstract void ExecuteCore(); 
23  // ....... 

bool InvokeAction(
               ControllerContext controllerContext,
               string actionName
) 

 public IActionInvoker ActionInvoker {
    get {
        if (_actionInvoker == null) {
            _actionInvoker = CreateActionInvoker();
        }
        return _actionInvoker;
    }
    set {
       _actionInvoker = value;
    }
}
   protected virtual IActionInvoker CreateActionInvoker() {
    return new ControllerActionInvoker();
}

public abstract class ActionResult
  {
      public abstract void ExecuteResult(ControllerContext context);
  }

if (View == null)
           {
               result = FindView(context); //calls the ViewResult‘s FindView() method
               View = result.View;
           }

           ViewContext viewContext = new ViewContext(context, View, ViewData, TempData);
           View.Render(viewContext, context.HttpContext.Response.Output);

protected abstract ViewEngineResult FindView(ControllerContext context); //this is implemented by                                                                         //the ViewResult

protected override ViewEngineResult FindView(ControllerContext context)
    {
        ViewEngineResult result = ViewEngineCollection.FindView(context, ViewName, MasterName);
        if (result.View != null)
        {
            return result;
        }
       //rest of the code omitted 
    }