AutoFac使用方法总结一：注册

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

 1     [Fact]
 2     public void can_resolve_myclass()
 3     {
 4         var builder = new ContainerBuilder();
 5         builder.RegisterType<MyClass>();
 6 
 7         IContainer container = builder.Build();
 8         var myClass = container.Resolve<MyClass>();
 9         Assert.NotNull(myClass);
10     }

注册为接口

 1     [Fact]
 2     public void register_as_interface()
 3     {
 4         var builder = new ContainerBuilder();
 5         builder.Register(c => new MyClass()).As<MyInterface>();
 6 
 7         IContainer container = builder.Build();
 8         Assert.NotNull(container.Resolve<MyInterface>());
 9         Assert.Throws(typeof (ComponentNotRegisteredException), () => container.Resolve<MyClass>());
10     }

使用lambda表达式进行注册

 1     [Fact]
 2     public void can_register_with_lambda()
 3     {
 4         var builder = new ContainerBuilder();
 5         builder.Register(c => new MyClass());
 6 
 7         IContainer container = builder.Build();
 8         var myClass = container.Resolve<MyClass>();
 9         Assert.NotNull(myClass);
10     }

带构造参数的注册

1     [Fact]
2     public void register_with_parameter()
3     {
4         var builder = new ContainerBuilder();
5         builder.Register(c => new MyParameter());
6         builder.Register(c => new MyClass(c.Resolve<MyParameter>()));
7         IContainer container = builder.Build();
8         Assert.NotNull(container.Resolve<MyClass>());
9     }

带属性赋值的注册

 1     [Fact]
 2     public void register_with_property()
 3     {
 4         var builder = new ContainerBuilder();
 5         builder.Register(c => new MyProperty());
 6         builder.Register(
 7             c => new MyClass()
 8                      {
 9                          Property = c.Resolve<MyProperty>()
10                      });
11         IContainer container = builder.Build();
12         var myClass = container.Resolve<MyClass>();
13         Assert.NotNull(myClass);
14         Assert.NotNull(myClass.Property);
15     }

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。

 1     [Fact]
 2     public void select_an_implementer_based_on_parameter_value()
 3     {
 4         var builder = new ContainerBuilder();
 5         builder.Register<IRepository>((c, p) =>
 6                              {
 7                                  var type = p.Named<string>("type");
 8                                  if (type == "test")
 9                                  {
10                                      return new TestRepository();
11                                  }
12                                  else
13                                  {
14                                      return new DbRepository();
15                                  }
16                              }).As<IRepository>();
17 
18         IContainer container = builder.Build();
19         var repository = container.Resolve<IRepository>(new NamedParameter("type", "test"));
20         Assert.Equal(typeof(TestRepository),repository.GetType());
21     }

AufoFac也可以用一个实例来注册，比如用在单例模式情况下：

 1     [Fact]
 2     public void register_with_instance()
 3     {
 4         var builder = new ContainerBuilder();
 5         builder.RegisterInstance(MyInstance.Instance).ExternallyOwned();
 6         IContainer container = builder.Build();
 7         var myInstance1 = container.Resolve<MyInstance>();
 8         var myInstance2 = container.Resolve<MyInstance>();
 9         Assert.Equal(myInstance1,myInstance2);
10     }

注册open generic类型

 1     [Fact]
 2     public void register_open_generic()
 3     {
 4         var builder = new ContainerBuilder();
 5         builder.RegisterGeneric(typeof (MyList<>));
 6         IContainer container = builder.Build();
 7         var myIntList = container.Resolve<MyList<int>>();
 8         Assert.NotNull(myIntList);
 9         var myStringList = container.Resolve<MyList<string>>();
10         Assert.NotNull(myStringList);
11     }

对于同一个接口，后面注册的实现会覆盖之前的实现

 1     [Fact]
 2     public void register_order()
 3     {
 4         var containerBuilder = new ContainerBuilder();
 5         containerBuilder.RegisterType<DbRepository>().As<IRepository>();
 6         containerBuilder.RegisterType<TestRepository>().As<IRepository>();
 7 
 8         IContainer container = containerBuilder.Build();
 9         var repository = container.Resolve<IRepository>();
10         Assert.Equal(typeof(TestRepository), repository.GetType());
11     }

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

 1     [Fact]
 2     public void register_order_defaults()
 3     {
 4         var containerBuilder = new ContainerBuilder();
 5         containerBuilder.RegisterType<DbRepository>().As<IRepository>();
 6         containerBuilder.RegisterType<TestRepository>().As<IRepository>().PreserveExistingDefaults();
 7 
 8         IContainer container = containerBuilder.Build();
 9         var repository = container.Resolve<IRepository>();
10         Assert.Equal(typeof (DbRepository), repository.GetType());
11     }

可以用Name来区分不同的实现，代替As方法

 1     [Fact]
 2     public void register_with_name()
 3     {
 4         var containerBuilder = new ContainerBuilder();
 5         containerBuilder.RegisterType<DbRepository>().Named<IRepository>("DB");
 6         containerBuilder.RegisterType<TestRepository>().Named<IRepository>("Test");
 7 
 8         IContainer container = containerBuilder.Build();
 9         var dbRepository = container.ResolveNamed<IRepository>("DB");
10         var testRepository = container.ResolveNamed<IRepository>("Test");
11         Assert.Equal(typeof(DbRepository), dbRepository.GetType());
12         Assert.Equal(typeof(TestRepository), testRepository.GetType());
13     }

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

 1     [Fact]
 2     public void choose_constructors()
 3     {
 4         var builder = new ContainerBuilder();
 5         builder.RegisterType<MyParameter>();
 6         builder.RegisterType<MyClass>().UsingConstructor(typeof (MyParameter));
 7         IContainer container = builder.Build();
 8         var myClass = container.Resolve<MyClass>();
 9         Assert.NotNull(myClass);
10     }

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

 1     [Fact]
 2     public void register_assembly()
 3     {
 4         var builder = new ContainerBuilder();
 5         builder.RegisterAssemblyTypes(Assembly.GetExecutingAssembly()).
 6             Where(t => t.Name.EndsWith("Repository")).
 7             AsImplementedInterfaces();
 8 
 9         IContainer container = builder.Build();
10         var repository = container.Resolve<IRepository>();
11         Assert.NotNull(repository);
12     }