Orchard源碼分析（7.2）：Controller相關

概述

默認狀況下，ASP.NET MVC內置的DefaultControllerFactory負責Controller實例的建立。Orchard定義了一個繼承自DefaultControllerFactory類的Orchard.Mvc.OrchardControllerFactory類並在OrchardStarter類中進行註冊：

         // 如下代碼來在Orchard.Environment.OrchardStarter類

          ControllerBuilder .Current.SetControllerFactory( new   OrchardControllerFactory ());

OrchardControllerFactory做用是能從Shell生命週期的Autofac"子容器"中解析(Resolver)Controller類型，再根據類型解析Controller實例。這裏就引出這些問題：Controller類型在何時被註冊到Autofac容器中，Controller的類型如何被解析出來，Controller的實例如何被解析出來。

 

1、Controller註冊

在激活Shell以前，會建立Shell的上下文對象ShellContext，在這個過程當中會將Shell須要用到的Controller註冊到Shell做用域的Autofac容器中：

                     // 如下代碼來在Orchard.Environment.ShellBuilders.ShellContainerFactory類的CreateContainer方法

                      foreach   ( var   item   in   blueprint.Controllers) {

                          var   serviceKeyName = (item.AreaName +   "/"   + item.ControllerName).ToLowerInvariant();

                          var   serviceKeyType = item.Type;

                        RegisterType(builder, item)

                            .EnableDynamicProxy(dynamicProxyContext)

                            .Keyed<   IController >(serviceKeyName)

                            .Keyed<   IController >(serviceKeyType)

                            .WithMetadata(   "ControllerType" , item.Type)

                            .InstancePerDependency()

                            .OnActivating(e =>s {

                                  // necessary to inject custom filters dynamically

                                  // see FilterResolvingActionInvoker

                                  var   controller = e.Instance   as   Controller ;

                                  if   (controller !=   null   )

                                    controller.ActionInvoker = (   IActionInvoker )e.Context.ResolveService( new   TypedService ( typeof   ( IActionInvoker )));

                            });

                    }

 

                      foreach   ( var   item   in   blueprint.HttpControllers) {

                          var   serviceKeyName = (item.AreaName +   "/"   + item.ControllerName).ToLowerInvariant();

                          var   serviceKeyType = item.Type;

                        RegisterType(builder, item)

                            .EnableDynamicProxy(dynamicProxyContext)

                            .Keyed<   IHttpController >(serviceKeyName)

                            .Keyed<   IHttpController >(serviceKeyType)

                            .WithMetadata(   "ControllerType" , item.Type)

                            .InstancePerDependency();

                    }

 

          // 如下代碼來在Orchard.Environment.ShellBuilders.ShellContainerFactory類

        private   IRegistrationBuilder < object   ,   ConcreteReflectionActivatorData ,   SingleRegistrationStyle > RegisterType( ContainerBuilder   builder,   ShellBlueprintItem   item) {

              return   builder.RegisterType(item.Type)

                .WithProperty(   "Feature" , item.Feature)

                .WithMetadata(   "Feature" , item.Feature);

        }

2、ControllerFactory

既然Controller已經被註冊到了Autofac容器中，則很容易提取出來：

      // 如下代碼來在Orchard.Mvc.ControllerFactory類

     ///   <summary>

      ///   Overrides the default controller factory to resolve controllers using LoC, based their areas and names.

      ///   </summary>

      public   class   OrchardControllerFactory   :   DefaultControllerFactory   {

          ///   <summary>

          ///   Tries to resolve an instance for the controller associated with a given service key for the work context scope.

          ///   </summary>

          ///   <typeparam name="T">   The type of the controller. </typeparam>

          ///   <param name="workContext">   The work context. </param>

          ///   <param name="serviceKey">   The service key for the controller.   </param>

          ///   <param name="instance">   The controller instance. </param>

          ///   <returns>   True if the controller was resolved; false otherwise.   </returns>

          protected   bool   TryResolve<T>( WorkContext   workContext,   object   serviceKey,   out   T instance) {

              if   (workContext !=   null   && serviceKey !=   null ) {

                  var   key =   new   KeyedService (serviceKey,   typeof   (T));

                  object   value;

                  if   (workContext.Resolve< ILifetimeScope   >().TryResolveService(key,   out   value)) {

                    instance = (T) value;

                      return   true   ;

                }

            }

 

            instance =   default (T);

              return   false   ;

        }

 

          ///   <summary>

          ///   Returns the controller type based on the name of both the controller and area.

          ///   </summary>

          ///   <param name="requestContext">   The request context from where to fetch the route data containing the area. </param>

          ///   <param name="controllerName">   The controller name. </param>

          ///   <returns>   The controller type. </returns>

          ///   <example>   ControllerName: Item, Area: Containers would return the type for the ItemController class. </example>

          protected   override   Type   GetControllerType(   RequestContext   requestContext,   string   controllerName) {

              var   routeData = requestContext.RouteData;

 

              // Determine the area name for the request, and fall back to stock orchard controllers

              var   areaName = routeData.GetAreaName();

 

              // Service name pattern matches the identification strategy

              var   serviceKey = (areaName +   "/"   + controllerName).ToLowerInvariant();

 

              // Now that the request container is known - try to resolve the controller information

              Meta < Lazy   < IController >> info;

              var   workContext = requestContext.GetWorkContext();

              if   (TryResolve(workContext, serviceKey,   out   info)) {

                  return   ( Type   ) info.Metadata[ "ControllerType" ];

            }

 

              return   null   ;

        }

 

          ///   <summary>

          ///   Returns an instance of the controller.

          ///   </summary>

          ///   <param name="requestContext">   The request context from where to fetch the route data containing the area. </param>

          ///   <param name="controllerType">   The controller type. </param>

          ///   <returns>   An instance of the controller if it's type is registered; null if otherwise.   </returns>

          protected   override   IController   GetControllerInstance(   RequestContext   requestContext,   Type   controllerType) {

              IController   controller;

              var   workContext = requestContext.GetWorkContext();

              if   (TryResolve(workContext, controllerType,   out   controller)) {

                  return   controller;

            }

 

              // fail as appropriate for MVC's expectations

              return   base   .GetControllerInstance(requestContext, controllerType);

        }

    }

 

 

3、ActionInvoker

在成功建立Controller實例後，會將其ActionInvoker設置成Orchard.Mvc.FilterResolvingActionInvoker。

咱們知道，ASP.NET MVC中，咱們能夠將Filter以Attribute的形式定義在Controller或Action上。Orchard提供了一個Filter Provider機制，便可以將一些Filter定義在其餘地方，在使用Filter以前再提取出來。這方面比較簡單，直接看FilterResolvingActionInvoker的定義：

      // 如下代碼來在Orchard.Mvc.Filters.FilterResolvingActionInvoker類

     public   class   FilterResolvingActionInvoker   :   ControllerActionInvoker   {

          private   readonly   IEnumerable <   IFilterProvider > _filterProviders;

 

          public   FilterResolvingActionInvoker( IEnumerable   < IFilterProvider > filterProviders) {

            _filterProviders = filterProviders;

        }

 

          protected   override   FilterInfo   GetFilters( ControllerContext   controllerContext,   ActionDescriptor   actionDescriptor) {

              var   filters=   base   .GetFilters(controllerContext, actionDescriptor);

              foreach ( var   provider   in   _filterProviders) {

                provider.AddFilters(filters);

            }

              return   filters;

        }

    }

 

只要一個Filter實現了Orchard.Mvc.Filters.FilterProvider:FilterProvider抽象類，就能很是方便的將Filter應用到全部Action之上。另外，高級的應用能夠直接實現IFilterProvider接口，不過通常實現FilterProvider抽象類就好了。

 

相關類型：

Orchard.Mvc.OrchardControllerFactory:System.Web.Mvc.DefaultActionInvoker

Orchard.Mvc.Filters.FilterResolvingActionInvoker:System.Web.Mvc.ControllerActionInvoker

Orchard.Mvc.Filters.IFilterProvider

Orchard.Environment.ShellBuilders.ShellContainerFactory

Orchard.Environment.AutofacUtil.DynamicProxy2.DynamicProxyContext