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：
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);
}
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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>());
}
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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);
}
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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>());
}
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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);
}
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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());
}
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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);
}
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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);
}
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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());
}
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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());
}
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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());
}
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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);
}
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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);
}
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