AutoFac使用方法总结:Part I

utoFac是.net平台下的IOC容器产品，它可以管理类之间的复杂的依赖关系。在使用方面主要是register和resolve两类操作。 这篇文章用单元测试的形式列举了AutoFac的常用使用方法：

注册部分

使用RegisterType进行注册

[Fact]

    public void can_resolve_myclass()

    {

        var builder = new ContainerBuilder();

        builder.RegisterType<MyClass>();



        IContainer container = builder.Build();

        var myClass = container.Resolve<MyClass>();

        Assert.NotNull(myClass);

    }

 注册为接口

[Fact]

    public void register_as_interface()

    {

        var builder = new ContainerBuilder();

        builder.Register(c => new MyClass()).As<MyInterface>();



        IContainer container = builder.Build();

        Assert.NotNull(container.Resolve<MyInterface>());

        Assert.Throws(typeof (ComponentNotRegisteredException), () => container.Resolve<MyClass>());

    }

使用lambda表达式进行注册

[Fact]

    public void can_register_with_lambda()

    {

        var builder = new ContainerBuilder();

        builder.Register(c => new MyClass());



        IContainer container = builder.Build();

        var myClass = container.Resolve<MyClass>();

        Assert.NotNull(myClass);

    }

带构造参数的注册

    [Fact]

    public void register_with_parameter()

    {

        var builder = new ContainerBuilder();

        builder.Register(c => new MyParameter());

        builder.Register(c => new MyClass(c.Resolve<MyParameter>()));

        IContainer container = builder.Build();

        Assert.NotNull(container.Resolve<MyClass>());

    }  

带属性赋值的注册

  [Fact]

    public void register_with_property()

    {

        var builder = new ContainerBuilder();

        builder.Register(c => new MyProperty());

        builder.Register(

            c => new MyClass()

                     {

                         Property = c.Resolve<MyProperty>()

                     });

        IContainer container = builder.Build();

        var myClass = container.Resolve<MyClass>();

        Assert.NotNull(myClass);

        Assert.NotNull(myClass.Property);

    }      

Autofac分离了类的创建和使用，这样可以根据输入参数（NamedParameter）动态的选择实现类。

  [Fact]

    public void select_an_implementer_based_on_parameter_value()

    {

        var builder = new ContainerBuilder();

        builder.Register<IRepository>((c, p) =>

                             {

                                 var type = p.Named<string>("type");

                                 if (type == "test")

                                 {

                                     return new TestRepository();

                                 }

                                 else

                                 {

                                     return new DbRepository();

                                 }

                             }).As<IRepository>();



        IContainer container = builder.Build();

        var repository = container.Resolve<IRepository>(new NamedParameter("type", "test"));

        Assert.Equal(typeof(TestRepository),repository.GetType());

    }

AufoFac也可以用一个实例来注册，比如用在单例模式情况下：

  [Fact]

    public void register_with_instance()

    {

        var builder = new ContainerBuilder();

        builder.RegisterInstance(MyInstance.Instance).ExternallyOwned();

        IContainer container = builder.Build();

        var myInstance1 = container.Resolve<MyInstance>();

        var myInstance2 = container.Resolve<MyInstance>();

        Assert.Equal(myInstance1,myInstance2);

    }

注册open generic类型

  [Fact]

    public void register_open_generic()

    {

        var builder = new ContainerBuilder();

        builder.RegisterGeneric(typeof (MyList<>));

        IContainer container = builder.Build();

        var myIntList = container.Resolve<MyList<int>>();

        Assert.NotNull(myIntList);

        var myStringList = container.Resolve<MyList<string>>();

        Assert.NotNull(myStringList);

    }

对于同一个接口，后面注册的实现会覆盖之前的实现

  [Fact]

    public void register_order()

    {

        var containerBuilder = new ContainerBuilder();

        containerBuilder.RegisterType<DbRepository>().As<IRepository>();

        containerBuilder.RegisterType<TestRepository>().As<IRepository>();



        IContainer container = containerBuilder.Build();

        var repository = container.Resolve<IRepository>();

        Assert.Equal(typeof(TestRepository), repository.GetType());

    }

如果不想覆盖的话，可以用PreserveExistingDefaults，这样会保留原来注册的实现。

  [Fact]

    public void register_order_defaults()

    {

        var containerBuilder = new ContainerBuilder();

        containerBuilder.RegisterType<DbRepository>().As<IRepository>();

        containerBuilder.RegisterType<TestRepository>().As<IRepository>().PreserveExistingDefaults();



        IContainer container = containerBuilder.Build();

        var repository = container.Resolve<IRepository>();

        Assert.Equal(typeof (DbRepository), repository.GetType());

    }

可以用Name来区分不同的实现，代替As方法

  [Fact]

    public void register_with_name()

    {

        var containerBuilder = new ContainerBuilder();

        containerBuilder.RegisterType<DbRepository>().Named<IRepository>("DB");

        containerBuilder.RegisterType<TestRepository>().Named<IRepository>("Test");



        IContainer container = containerBuilder.Build();

        var dbRepository = container.ResolveNamed<IRepository>("DB");

        var testRepository = container.ResolveNamed<IRepository>("Test");

        Assert.Equal(typeof(DbRepository), dbRepository.GetType());

        Assert.Equal(typeof(TestRepository), testRepository.GetType());

    }

如果一个类有多个构造函数的话，可以在注册时候选择不同的构造函数

  [Fact]

    public void choose_constructors()

    {

        var builder = new ContainerBuilder();

        builder.RegisterType<MyParameter>();

        builder.RegisterType<MyClass>().UsingConstructor(typeof (MyParameter));

        IContainer container = builder.Build();

        var myClass = container.Resolve<MyClass>();

        Assert.NotNull(myClass);

    }

AutoFac可以注册一个Assemble下所有的类，当然，也可以根据类型进行筛选

  [Fact]

    public void register_assembly()

    {

        var builder = new ContainerBuilder();

        builder.RegisterAssemblyTypes(Assembly.GetExecutingAssembly()).

            Where(t => t.Name.EndsWith("Repository")).

            AsImplementedInterfaces();



        IContainer container = builder.Build();

        var repository = container.Resolve<IRepository>();

        Assert.NotNull(repository);

    }