IOC容器又像一個插座，將電輸送到須要的每一處。須要充電的話，就鏈接，不須要就不鏈接，節省資源，不用時時刻刻連上電源了。省電的，哈哈。測試

AutoFac是.net平臺下的IOC容器產品，它能夠管理類之間的複雜的依賴關係。在使用方面主要是register和resolve兩類操做。這篇文章用單元測試的形式列舉了AutoFac的經常使用使用方法：

註冊部分

使用RegisterType進行註冊

 
       [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);  }

註冊爲接口

 
       [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表達式進行註冊

 
       [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);  }

帶構造參數的註冊

 
       [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>());  }

帶屬性賦值的註冊

 
       [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分離了類的建立和使用，這樣能夠根據輸入參數（NamedParameter）動態的選擇實現類。

 
       [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也能夠用一個實例來註冊，好比用在單例模式狀況下：

 
       [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);  }

註冊open generic類型

 
       [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);  }

對於同一個接口，後面註冊的實現會覆蓋以前的實現

 
       [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());  }

若是不想覆蓋的話，能夠用PreserveExistingDefaults，這樣會保留原來註冊的實現。

 
       [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());  }

能夠用Name來區分不一樣的實現，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());  }

若是一個類有多個構造函數的話，能夠在註冊時候選擇不一樣的構造函數

 
       [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能夠註冊一個Assemble下全部的類，固然，也能夠根據類型進行篩選

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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);  }

AutoFac使用方法總結:Part II

APR 6TH, 2012 | COMMENTS

事件

AutoFac支持三種事件：OnActivating，OnActivated，OnRelease。OnActivating在註冊組件使用以前會被調用，此時能夠替換實現類或者進行一些其餘的初始化工做，OnActivated在實例化以後會被調用，OnRelease在組件釋放以後會被調用。

 
         public class MyEvent : IDisposable  {  public MyEvent(string input)  {  Console.WriteLine(input);  }   public MyEvent()  {  Console.WriteLine("Init");  }   public void Dispose()  {  Console.WriteLine("Dispose");  }  }

 
         public void test_event()  {  var builder = new ContainerBuilder();  builder.RegisterType<MyEvent>().  OnActivating(e => e.ReplaceInstance(new MyEvent("input"))).  OnActivated(e => Console.WriteLine("OnActivated")).  OnRelease(e => Console.WriteLine("OnRelease"));    using (IContainer container = builder.Build())  {  using (var myEvent = container.Resolve<MyEvent>())  {  }  }  }

此時的輸出爲：

 
        Init input OnActivated Dispose OnRelease

利用事件能夠在構造對象以後調用對象的方法：

 
         [Fact]  public void call_method_when_init()  {  var builder = new ContainerBuilder();  builder.RegisterType<MyClassWithMethod>().OnActivating(e => e.Instance.Add(5));  IContainer container = builder.Build();  Assert.Equal(5, container.Resolve<MyClassWithMethod>().Index);  }  public class MyClassWithMethod  {  public int Index { get; set; }  public void Add(int value)  {  Index = Index + value;  }  }

循環依賴

循環依賴是個比較頭疼的問題，在AutoFac中不少循環依賴的場景不被支持：

 
         public class ClassA  {  private readonly ClassB b;   public ClassA(ClassB b)  {  this.b = b;  }  }   public class ClassB  {  public ClassA A { get; set; }   }   [Fact]  public void circular_dependencies_exception()  {  var builder = new ContainerBuilder();  builder.Register(c => new ClassB(){A = c.Resolve<ClassA>()});  builder.Register(c => new ClassA(c.Resolve<ClassB>()));  IContainer container = builder.Build();  Assert.Throws(typeof(DependencyResolutionException), ()=>container.Resolve<ClassA>());  }

能夠部分的解決這種循環依賴的問題，前提是ClassA和ClassB的生命週期不能都是InstancePerDependency

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 [Fact]  public void circular_dependencies_ok()  {  var builder = new ContainerBuilder();  builder.RegisterType<ClassB>().  PropertiesAutowired(PropertyWiringFlags.AllowCircularDependencies).SingleInstance();  builder.Register(c => new ClassA(c.Resolve<ClassB>()));  IContainer container = builder.Build();  Assert.NotNull(container.Resolve<ClassA>());  Assert.NotNull(container.Resolve<ClassB>());  Assert.NotNull(container.Resolve<ClassB>().A);  }

AutoFac使用方法總結:Part III

APR 6TH, 2012 | COMMENTS

生命週期

AutoFac中的生命週期概念很是重要，AutoFac也提供了強大的生命週期管理的能力。

AutoFac定義了三種生命週期：

Per Dependency
Single Instance
Per Lifetime Scope

Per Dependency爲默認的生命週期，也被稱爲’transient’或’factory’，其實就是每次請求都建立一個新的對象

 
           [Fact]  public void per_dependency()  {  var builder = new ContainerBuilder();  builder.RegisterType<MyClass>().InstancePerDependency();  IContainer container = builder.Build();  var myClass1 = container.Resolve<MyClass>();  var myClass2 = container.Resolve<MyClass>();  Assert.NotEqual(myClass1,myClass2);  }

Single Instance也很好理解，就是每次都用同一個對象

 
           [Fact]  public void single_instance()  {  var builder = new ContainerBuilder();  builder.RegisterType<MyClass>().SingleInstance();   IContainer container = builder.Build();  var myClass1 = container.Resolve<MyClass>();  var myClass2 = container.Resolve<MyClass>();   Assert.Equal(myClass1,myClass2);  }

Per Lifetime Scope，同一個Lifetime生成的對象是同一個實例

 
           [Fact]  public void per_lifetime_scope()  {  var builder = new ContainerBuilder();  builder.RegisterType<MyClass>().InstancePerLifetimeScope();   IContainer container = builder.Build();  var myClass1 = container.Resolve<MyClass>();  var myClass2 = container.Resolve<MyClass>();   ILifetimeScope inner = container.BeginLifetimeScope();  var myClass3 = inner.Resolve<MyClass>();  var myClass4 = inner.Resolve<MyClass>();   Assert.Equal(myClass1,myClass2);  Assert.NotEqual(myClass2,myClass3);  Assert.Equal(myClass3,myClass4);  }

 
           [Fact]  public void life_time_and_dispose()  {  var builder = new ContainerBuilder();  builder.RegisterType<Disposable>();   using (IContainer container = builder.Build())  {  var outInstance = container.Resolve<Disposable>(new NamedParameter("name", "out"));   using(var inner = container.BeginLifetimeScope())  {  var inInstance = container.Resolve<Disposable>(new NamedParameter("name", "in"));  }//inInstance dispose here  }//out dispose here  }

AutoFac Ioc依賴注入容器

AutoFac使用方法總結:Part I

註冊部分

AutoFac使用方法總結:Part II

事件

循環依賴

AutoFac使用方法總結:Part III

生命週期