namespace MEF.Repository
{public interface ITestRepository{string GetTestString();}
}

    [Export(typeof(ITestRepository))]public class TestRepository:ITestRepository{public string GetTestString(){return "Hello World";}}

using System.ComponentModel.Composition;

            //设置MEF依赖注入容器DirectoryCatalog catalog = new DirectoryCatalog(AppDomain.CurrentDomain.SetupInformation.PrivateBinPath);MefDependencySolver solver = new MefDependencySolver(catalog);DependencyResolver.SetResolver(solver);

public class MefDependencySolver : IDependencyResolver{private readonly ComposablePartCatalog _catalog;private const string MefContainerKey = "MefContainerKey";public MefDependencySolver(ComposablePartCatalog catalog){_catalog = catalog;}public CompositionContainer Container{get{if (!HttpContext.Current.Items.Contains(MefContainerKey)){HttpContext.Current.Items.Add(MefContainerKey, new CompositionContainer(_catalog));}CompositionContainer container = (CompositionContainer)HttpContext.Current.Items[MefContainerKey];HttpContext.Current.Application["Container"] = container;return container;}}public object GetService(Type serviceType){string contractName = AttributedModelServices.GetContractName(serviceType);return Container.GetExportedValueOrDefault<object>(contractName);}public IEnumerable<object> GetServices(Type serviceType){return Container.GetExportedValues<object>(serviceType.FullName);}}
}

    [Export]public class HomeController : Controller{[Import]public ITestRepository Repository { get; set; }public ActionResult Index(){Repository.GetTestString();ViewBag.Message = "Welcome to ASP.NET MVC!" + Repository.GetTestString();return View();}