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();
}
}