IOC容器Autofac

//类ContainerBuilder中的方法:

RegisterType<T>()//注册类型T

AsImplementedInterfaces()//表示注册的类型，以接口的方式注册

Build()//创建一个容器

接口IContainer的方法：

Resolve<T>()//从容器中取出一个T类型的实例

1. 如何实现AsImplementedInterfaces()

builder.RegisterType<ListMovieFinder>().AsImplementedInterfaces(); //以类ListMovieFinder的接口IMovieFinder注册

那么我使用 Resolve<IMovieFinder>()要获取一个接口实例的时候，会返回一个ListMovieFinder的实例

2. 如何实现对同一个类型的注册，后面的覆盖前面的注册， 如源代码中:

builder.RegisterType<ListMovieFinder>().AsImplementedInterfaces();
builder.RegisterType<DBMovieFinder>().AsImplementedInterfaces();

 后面的DBMovieFinder会覆盖掉ListMovieFinder的注册

这样，当我调用 Resolve<IMovieFinder>()要获取一个接口实例的时候，会返回一个DBMovieFinder的实例

protected void Application_Start()
{
    var builder = new ContainerBuilder();
    builder.RegisterControllers(typeof(MvcApplication).Assembly);
    var container = builder.Build();
    DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

    // Other MVC setup...
}

1. 首先创建一个ContainerBuilder(它会稍后为我们提供一个容器，我们可以从中取出我们所需的对象实例)

2. 注册当前Assembly中的所有Controllers到Builder，这样Builder就获取了当前MVC项目中的所有Controller类型

3. 创建容器

4. 用AutofacDependencyResolver替换MVC默认的DependencyResolver

一、使用Entity Framework Code First， 写代码创建Student表

 public class SchoolContext : DbContext
    {
        public SchoolContext()
            : base("DefaultConnection")
        {
        }

        public DbSet<Student> Students { get; set; }
    }

    [Table("Student")]
    public class Student
    {
        [Key]
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }

首先我们可以创建一个接口:

 public interface IStudentRepository
 {
    IEnumerable<Student> GetStudents();
 }

然后, 创建一个集成这个接口的类，这个类并不访问数据库，但是提供我们开发页面所需的数据。

  public class StubStudentRepository:IStudentRepository
  {
        public IEnumerable<Student> GetStudents()
        {
            return new[]
                       {
                           new Student {Id = 1, Name = "Sam", Age = 14}
                       };
        }
  }

  public class HomeController : Controller
    {
        public ActionResult Index()
        {
            IStudentRepository studentRepository = new StubStudentRepository();
            //IStudentRepository studentRepository = new StudentRepository();//注释掉访问数据层的代码，用Stub类代替
            var students = studentRepository.GetStudents();
            
            return View(students);
        }
    }

实例化

IStudentRepository studentRepository = new StubStudentRepository()

Autofac大显身手

   public class HomeController : Controller
    {
        private readonly IStudentRepository _studentRepository;
        //由构造函数来提供Controller的依赖IStudentRepository
        public HomeController(IStudentRepository studentRepository)
        {
            _studentRepository = studentRepository;
        }

        public ActionResult Index()
        {
            var students = _studentRepository.GetStudents();
            
            return View(students);
        }
    }

 修改Global.asax,

public class MvcApplication : System.Web.HttpApplication
{
        protected void Application_Start()
        {
            //Autofac初始化过程
            var builder = new ContainerBuilder();
            builder.RegisterControllers(typeof(MvcApplication).Assembly);//注册所有的Controller
            //开发环境下，使用Stub类
            builder.RegisterAssemblyTypes(typeof (MvcApplication).Assembly).Where(
                t => t.Name.EndsWith("Repository") && t.Name.StartsWith("Stub")).AsImplementedInterfaces();
            //发布环境下，使用真实的数据访问层
            //builder.RegisterAssemblyTypes(typeof(MvcApplication).Assembly).Where(
            //   t => t.Name.EndsWith("Repository")).AsImplementedInterfaces();

            var container = builder.Build();
            DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

            //其它的初始化过程
            ........
        }
}

所有的controller就都是使用Stub类的实例

//开发环境下，使用Stub类
builder.RegisterAssemblyTypes(typeof (MvcApplication).Assembly).Where(
             t => t.Name.EndsWith("Repository") && t.Name.StartsWith("Stub")).AsImplementedInterfaces();

private static void AutofacMvcRegister()
        {
            ContainerBuilder builder = new ContainerBuilder();
            builder.RegisterGeneric(typeof(DbContextBase<>)).As(typeof(IDataRepository<>));
            Type baseType = typeof(IDependency);
            Assembly[] assemblies = Assembly.GetExecutingAssembly().GetReferencedAssemblies()
                .Select(Assembly.Load).ToArray();
            assemblies = assemblies.Union(new[] { Assembly.GetExecutingAssembly() }).ToArray();
            builder.RegisterAssemblyTypes(assemblies)
                .Where(type => baseType.IsAssignableFrom(type) && !type.IsAbstract)
                .AsImplementedInterfaces().InstancePerLifetimeScope();//InstancePerLifetimeScope 保证生命周期基于请求

            //无效
            //builder.RegisterType<DefaultCacheAdapter>().PropertiesAutowired().As<ICacheStorage>();

            builder.RegisterControllers(Assembly.GetExecutingAssembly());
            builder.RegisterFilterProvider();
            IContainer container = builder.Build();
            DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
        }

 public class ListMovieFinder : IMovieFinder
    {
        public List<Movie> FindAll()
        {
            return new List<Movie>
                       {
                           new Movie
                               {
                                   Name = "Die Hard.wmv"
                               },
                           new Movie
                               {
                                   Name = "My Name is John.MPG"
                               }
                       };
        }
    }

 public interface IMovieFinder
    {
        List<Movie> FindAll();
    }

    public class Movie
    {
        public string Name { get; set; }
    }

public class MPGMovieLister
    {
        private readonly IMovieFinder _movieFinder;
        public MPGMovieLister(IMovieFinder movieFinder)
        {
            _movieFinder = movieFinder;
        }

        public Movie[] GetMPG()
        {
            var allMovies = _movieFinder.FindAll();
            return allMovies.Where(m => m.Name.EndsWith(".MPG")).ToArray();
        }
    }

internal class Program
    {
        private static IContainer _container;
        private static void Main(string[] args)
        {
            InitIoC();

            var lister = _container.Resolve<MPGMovieLister>();

            foreach (var movie in lister.GetMPG())
            {
                Console.WriteLine(movie.Name);
            }
            Console.Read();
        }


        private static void InitIoC()
        {
            var builder = new ContainerBuilder();
            builder.RegisterType<ListMovieFinder>().AsImplementedInterfaces();
            //builder.RegisterType<DBMovieFinder>().AsImplementedInterfaces();
            builder.RegisterType<MPGMovieLister>();
            _container = builder.Build();
        }
    }