Orchard源码分析（7.2）：Controller相关

概述

默认情况下，ASP.NET MVC内置的DefaultControllerFactory负责Controller实例的创建。Orchard定义了一个继承自DefaultControllerFactory类的Orchard.Mvc.OrchardControllerFactory类并在OrchardStarter类中进行注册：

// 以下代码来在Orchard.Environment.OrchardStarter类

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

OrchardControllerFactory作用是能从Shell生命周期的Autofac"子容器"中解析(Resolver)Controller类型，再根据类型解析Controller实例。这里就引出这些问题：Controller类型在什么时候被注册到Autofac容器中，Controller的类型如何被解析出来，Controller的实例如何被解析出来。

一、Controller注册

在激活Shell之前，会创建Shell的上下文对象ShellContext，在这个过程中会将Shell需要用到的Controller注册到Shell作用域的Autofac容器中：

// 以下代码来在Orchard.Environment.ShellBuilders.ShellContainerFactory类的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();

}

// 以下代码来在Orchard.Environment.ShellBuilders.ShellContainerFactory类

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

return builder.RegisterType(item.Type)

.WithProperty( "Feature", item.Feature)

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

}

二、ControllerFactory

既然Controller已经被注册到了Autofac容器中，则很容易提取出来：

// 以下代码来在Orchard.Mvc.ControllerFactory类

/// <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);

}

三、ActionInvoker

在成功创建Controller实例后，会将其ActionInvoker设置成Orchard.Mvc.FilterResolvingActionInvoker。

我们知道，ASP.NET MVC中，我们可以将Filter以Attribute的形式定义在Controller或Action上。Orchard提供了一个Filter Provider机制，即可以将一些Filter定义在其他地方，在使用Filter之前再提取出来。这方面比较简单，直接看FilterResolvingActionInvoker的定义：

// 以下代码来在Orchard.Mvc.Filters.FilterResolvingActionInvoker类

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;

}

只要一个Filter实现了Orchard.Mvc.Filters.FilterProvider:FilterProvider抽象类，就能非常方便的将Filter应用到所有Action之上。另外，高级的应用可以直接实现IFilterProvider接口，不过一般实现FilterProvider抽象类就行了。