AutoFac在项目中应用的体会

AutoFac的工作原理就是：注册类并映射到接口，通过注入后返回相应实例化的类！

先来简单介绍下Autofac的使用

1、通过Nuget或代码安装autofac

安装autofac :install-package autofac

安装对mvc4的支持：install -package autofac.mvc4

2、新建相应的类及接口，并在autofac中进行映射

2.1、新建接口 INewsHelper

1 namespace test.Interface
2 {
3     public interface INewsHelper
4     {
5         string GetNewInfo(int id);
6     }
7 }

2.2、新建类NewsHelper并继承INewsHelper

 1 namespace test.Helper
 2 {
 3     public class NewsHelper:INewsHelper
 4     {
 5         public string GetNewInfo(int id)
 6         {
 7             return "newshelper";
 8         }
 9     }
10 }

2.3 新建类SubjectHelper并继承INewsHelper

 1 namespace test.Helper
 2 {
 3     public class SubjectHelper:INewsHelper
 4     {
 5         public string GetNewInfo(int id)
 6         {
 7             return "subjecthelper";
 8         }
 9  
10     }
11 }

2.4 在autofac中注册并映射

 1 namespace test
 2 {
 3     // 注意: 有关启用 IIS6 或 IIS7 经典模式的说明，
 4     // 请访问 http://go.microsoft.com/?LinkId=9394801
 5  
 6     public class MvcApplication : System.Web.HttpApplication
 7     {
 8         protected void Application_Start()
 9         {
10             var builder = new ContainerBuilder();
11             builder.RegisterType<CategoryHelper>().As<ICategoryHelper>().InstancePerHttpRequest();
12  
13             builder.RegisterType<NewsHelper>().Named<INewsHelper>("news");
14             builder.RegisterType<SubjectHelper>().Named<INewsHelper>("subject");
15  
16             builder.RegisterControllers(Assembly.GetExecutingAssembly());
17             var container = builder.Build();
18             DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
19  
20  
21             AreaRegistration.RegisterAllAreas();
22             WebApiConfig.Register(GlobalConfiguration.Configuration);
23             FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
24             RouteConfig.RegisterRoutes(RouteTable.Routes);
25             BundleConfig.RegisterBundles(BundleTable.Bundles);
26             AuthConfig.RegisterAuth();
27         }
28     }
29 }

3、新建ServiceGetter类及 IServiceGetter接口

3.1

1 namespace test.Interface
2 {
3     public interface IServiceGetter
4     {
5          T GetByName<T>(string name);
6     }
7 }

3.2

 1 namespace test.Helper
 2 {
 3     public class ServiceGetter:IServiceGetter
 4     {
 5         public T GetByName<T>(string name)
 6         {
 7             return AutofacDependencyResolver.Current.RequestLifetimeScope.ResolveNamed<T>(name);
 8         }
 9     }
10 }

3.3 增加注册

builder.RegisterType<ServiceGetter>().As<IServiceGetter>();

整个步骤3做了一件事，给中间件一个泛型的name,由中间件向autofac将相应的class的实例并返回，说白了就是干了下面这句代码的事：

AutofacDependencyResolver.Current.RequestLifetimeScope.ResolveNamed<INewsHelper>("news");

4、通过构造函数进行注入

 1 namespace test.Controllers
 2 {
 3     public class HomeController : Controller
 4     {
 5          
 6         private IServiceGetter getter;
 7  
 8         public HomeController(IServiceGetter getter)
 9         {
10              
11             this.getter = getter;
12  
13         }
14  
15         public ActionResult Index()
16         {
17              
18             ViewBag.Message = getter.GetByName<INewsHelper>("subject").GetNewInfo(1);
19             return View();
20         }
21         
22     }
23 }