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。
相关类型：
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
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