项目中引入Autofac的目的是为了实现控制反转，即IoC，Inversion of Control。控制反转可以有效的降低类之间的相互依赖关系，增加架构的弹性，降低软件复杂度。

　　示例代码：

　　IProvinceRepository.cs

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace Libing.Portal.Web.Models{    public interface IProvinceRepository    {        List
      
        GetProvinceList();    }}
      

　　ProvinceRepository.cs

using System;using System.Collections.Generic;using System.Linq;using System.Web;namespace Libing.Portal.Web.Models{    public class ProvinceRepository : IProvinceRepository    {        public List
      
        GetProvinceList()        {            using (var ctx = new PortalContext())            {                return ctx.Provinces.ToList();            }        }    }}
      

　　ProvinceController.cs

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.Mvc;namespace Libing.Portal.Web.Controllers{    public class ProvinceController : Controller    {        private Libing.Portal.Web.Models.IProvinceRepository _provinceRepository;        public ProvinceController(Libing.Portal.Web.Models.IProvinceRepository provinceRepository)        {            _provinceRepository = provinceRepository;        }        public ActionResult Index()        {            return View(_provinceRepository.GetProvinceList());        }    }}

　　ICityRepository.cs

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace Libing.Portal.Web.Models{    public interface ICityRepository    {        List
      
        GetCityList();    }}
      

　　CityRepository.cs

using System;using System.Collections.Generic;using System.Linq;using System.Web;namespace Libing.Portal.Web.Models{    public class CityRepository : ICityRepository    {        public List
      
        GetCityList()        {            using (var ctx = new PortalContext())            {                return ctx.Cities.ToList();            }        }    }}
      

　　CityController.cs

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.Mvc;namespace Libing.Portal.Web.Controllers{    public class CityController : Controller    {        private Libing.Portal.Web.Models.IProvinceRepository _provinceRepository;        private Libing.Portal.Web.Models.ICityRepository _cityRepository;        public CityController(Libing.Portal.Web.Models.IProvinceRepository provinceRepository, Libing.Portal.Web.Models.ICityRepository cityRepository)        {            _provinceRepository = provinceRepository;            _cityRepository = cityRepository;        }        public ActionResult Index()        {            return View(_cityRepository.GetCityList());        }    }}

　　Global.cs

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.Http;using System.Web.Mvc;using System.Web.Routing;using System.Reflection;using Autofac;using Autofac.Integration.Mvc;namespace Libing.Portal.Web{    // Note: For instructions on enabling IIS6 or IIS7 classic mode,     // visit http://go.microsoft.com/?LinkId=9394801    public class MvcApplication : System.Web.HttpApplication    {        protected void Application_Start()        {            AreaRegistration.RegisterAllAreas();            #region Autofac注入依赖            var builder = new ContainerBuilder();            SetupResolveRules(builder);            builder.RegisterControllers(Assembly.GetExecutingAssembly());            var container = builder.Build();            DependencyResolver.SetResolver(new AutofacDependencyResolver(container));            #endregion            WebApiConfig.Register(GlobalConfiguration.Configuration);            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);            RouteConfig.RegisterRoutes(RouteTable.Routes);        }        private static void SetupResolveRules(ContainerBuilder builder)        {            builder.RegisterType
      
       ().As
       
        ();            builder.RegisterType
        
         ().As
         
          ();        }    }}
         
        
       
      

　　在Global.cs中的SetupResolveRules可以使用下面的方式来注册：

private static void SetupResolveRules(ContainerBuilder builder){    builder.RegisterAssemblyTypes(Assembly.GetExecutingAssembly())        .Where(t => t.Name.EndsWith("Repository"))        .AsImplementedInterfaces();}

　　利用ContainerBuilder的RegisterAssemblyTypes()方法来注册组件中的所有类，通过Where()筛选出全部以“Repository”结尾的类，并自动找出这些类所实现的接口，然后设定与其对应。