AutoFac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
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[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
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[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
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[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
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[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
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[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。
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[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：
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[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
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[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
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[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。
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[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
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[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
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[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
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[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); }
