.NET 5中 Autofac 的使用

DI 依賴注入、IOC 控制反轉(zhuǎn)以及 AOP 切面編程

Autofac 容器

Autofac 是一款.NET IoC 容器 . 它管理類之間的依賴關(guān)系, 從而使 應(yīng)用在規(guī)模及復(fù)雜性增長的情況下依然可以輕易地修改 . 它的實現(xiàn)方式是將常規(guī)的.net類當(dāng)做 組件 處理.

  1. 安裝 NuGet 程序包： Autofac 6.0.0
  2. 創(chuàng)建一個 ContainerBuiler
  3. 注冊接口和實現(xiàn)關(guān)系
  4. 通過 ContainerBuiler 的 Build 方法，得到 IContainer 容器
  5. 通過 IContainer 容器獲取實例
  6. 使用服務(wù)
  • ITestServiceA 和 TestServiceA 
    public interface ITestServiceA
    {
        void Show();
    }

    public class TestServiceA : ITestServiceA
    {
        public TestServiceA()
        {
            Console.WriteLine($"{this.GetType().Name} 被構(gòu)造了...");
        }

        public void Show()
        {
            Console.WriteLine($"This is a {this.GetType().Name} Instance...");
        }
    }
  • Program 中的 Main 方法
 var builder = new ContainerBuilder();
 builder.RegisterType<TestServiceA>().As<ITestServiceA>();
 var container = builder.Build();

 // 獲取服務(wù)實例
 var testService = container.Resolve<ITestServiceA>();
 testService.Show();

Autofac 多種注入方式

  • ITestServiceB 和 TestServiceB 
    public interface ITestServiceB
    {
        void Show();
    }

    public class TestServiceB : ITestServiceB
    {
        private ITestServiceA _testServiceA;

        public void SetService(ITestServiceA testServiceA)
        {
            _testServiceA = testServiceA;
        }

        public TestServiceB()
        {
            Console.WriteLine($"{this.GetType().Name} 被構(gòu)造了...");
        }

        public void Show()
        {
            // _testServiceA.Show();
            Console.WriteLine($"This is a {this.GetType().Name} Instance...");
        }
    }
  • ITestServiceC 和 TestServiceC 
    public interface ITestServiceC
    {
        void Show();
    }

    public class TestServiceC : ITestServiceC
    {
        public TestServiceC()
        {
            Console.WriteLine($"{this.GetType().Name} 被構(gòu)造了...");
        }

        public void Show()
        {
            Console.WriteLine($"This is a {this.GetType().Name} Instance...");
        }
    }
  • ITestServiceD 和 TestServiceD 
    public interface ITestServiceD
    {
        void Show();
    }

    public class TestServiceD : ITestServiceD
    {
        public ITestServiceA TestServiceA { get; set; }
        public ITestServiceB TestServiceB { get; set; }
        public ITestServiceC TestServiceC { get; set; }

        public TestServiceD()
        {
            Console.WriteLine($"{this.GetType().Name} 被構(gòu)造了...");
        }

        public void Show()
        {
            // TestServiceA.Show();
            // TestServiceB.Show();
            // TestServiceC.Show();
            Console.WriteLine($"This is a {this.GetType().Name} Instance...");
        }
    }
  1. 構(gòu)造函數(shù)注入
 var builder = new ContainerBuilder();
 builder.RegisterType<TestServiceA>().As<ITestServiceA>();
 builder.RegisterType<TestServiceB>().As<ITestServiceB>();
 builder.RegisterType<TestServiceC>().As<ITestServiceC>();
 builder.RegisterType<TestServiceD>().As<ITestServiceD>();
 var container = builder.Build();

 // 獲取服務(wù)實例
 var testService = container.Resolve<ITestServiceA>();
 testService.Show();
  1. 屬性注入
 var builder = new ContainerBuilder();
 builder.RegisterType<TestServiceA>().As<ITestServiceA>();
 builder.RegisterType<TestServiceB>().As<ITestServiceB>();
 builder.RegisterType<TestServiceC>().As<ITestServiceC>();
 builder.RegisterType<TestServiceD>().As<ITestServiceD>().PropertiesAutowired();
 var container = builder.Build();

 // 獲取服務(wù)實例
 var testService = container.Resolve<ITestServiceD>();
 testService.Show();
  1. 方法注入
 var builder = new ContainerBuilder();
 builder.RegisterType<TestServiceA>().As<ITestServiceA>();
 builder.RegisterType<TestServiceB>().OnActivated(e => 
          e.Instance.SetService(e.Context.Resolve<ITestServiceA>())
 ).As<ITestServiceB>();
 builder.RegisterType<TestServiceC>().As<ITestServiceC>();
 builder.RegisterType<TestServiceD>().As<ITestServiceD>();
 var container = builder.Build();

 // 獲取服務(wù)實例
 var testService = container.Resolve<ITestServiceB>();
 testService.Show();

Autofac 生命周期

  1. InstancePerDependency ：默認模式，每次調(diào)用，都會重新實例化對象；每次請求都創(chuàng)建一個新的對象；
var builder = new ContainerBuilder();
builder.RegisterType<TestServiceA>().As<ITestServiceA>().InstancePerDependency();
var container = builder.Build();
var testServiceA = container.Resolve<ITestServiceA>();
var testServiceA1 = container.Resolve<ITestServiceA>();
Console.WriteLine(object.ReferenceEquals(testServiceA,testServiceA1));
  1. SingleInstance ：單例模式，每次調(diào)用，都會使用同一個實例化的對象；每次都用同一個對象；
var builder = new ContainerBuilder();
builder.RegisterType<TestServiceA>().As<ITestServiceA>().SingleInstance();
var container = builder.Build();
var testServiceA = container.Resolve<ITestServiceA>();
var testServiceA1 = container.Resolve<ITestServiceA>();
Console.WriteLine(object.ReferenceEquals(testServiceA,testServiceA1));
  1. InstancePerLifetimeScope ： 同一個生命周期域中，每次調(diào)用，都會使用同一個實例化的對象；每次都用同一個對象；且每個不同的生命周期域中的實例是唯一的，不共享的。
var builder = new ContainerBuilder();
builder.RegisterType<TestServiceA>().As<ITestServiceA>().InstancePerLifetimeScope();
var container = builder.Build();
ITestServiceA testServiceA15;
ITestServiceA testServiceA16;
using (var scope1 = container.BeginLifetimeScope())
{
    var testServiceA11 = scope1.Resolve<ITestServiceA>();
    var testServiceA12 = scope1.Resolve<ITestServiceA>();
    Console.WriteLine(object.ReferenceEquals(testServiceA11,testServiceA12));
    testServiceA15 = testServiceA12;
}
using (var scope1 = container.BeginLifetimeScope())
{
    var testServiceA13 = scope1.Resolve<ITestServiceA>();
    var testServiceA14 = scope1.Resolve<ITestServiceA>();
    Console.WriteLine(object.ReferenceEquals(testServiceA13,testServiceA14));
    testServiceA16 = testServiceA14;
}
Console.WriteLine(object.ReferenceEquals(testServiceA15,testServiceA16));
  1. InstancePerMatchingLifetimeScope ： 同一個匹配的生命周期域中，每次調(diào)用，都會使用同一個實例化的對象；每次都用同一個對象；且每個不匹配的生命周期域中的實例是唯一的，不共享的。
var builder = new ContainerBuilder();
builder.RegisterType<TestServiceA>().As<ITestServiceA>()
    .InstancePerMatchingLifetimeScope("Run2948");
var container = builder.Build();
ITestServiceA testServiceA15;
ITestServiceA testServiceA16;
using (var scope1 = container.BeginLifetimeScope("Run2948"))
{
    var testServiceA11 = scope1.Resolve<ITestServiceA>();
    using (var scope2 = container.BeginLifetimeScope())
    {
        var testServiceA12 = scope2.Resolve<ITestServiceA>();
        Console.WriteLine(object.ReferenceEquals(testServiceA11,testServiceA12));
    }
    testServiceA15 = testServiceA11;
}
using (var scope1 = container.BeginLifetimeScope("Run2948"))
{
    var testServiceA13 = scope1.Resolve<ITestServiceA>();
    using (var scope2 = container.BeginLifetimeScope())
    {
        var testServiceA14 = scope2.Resolve<ITestServiceA>();
        Console.WriteLine(object.ReferenceEquals(testServiceA13,testServiceA14));
    }
    testServiceA16 = testServiceA13;
}
Console.WriteLine(object.ReferenceEquals(testServiceA15,testServiceA16));

  1. InstancePerOwned ： 在一個所擁有的實例創(chuàng)建的生命周期中，每次調(diào)用，都會使用同一個實例化的對象；每次都用同一個對象；（較少使用）

  2. InstancePerHttpRequest ： 同一次Http請求上下文中，每次調(diào)用，都會使用同一個實例化的對象；每次都用同一個對象；僅適用于 ASP.NET (CORE) MVC 或 WebForm 應(yīng)用程序

Autofac 支持配置文件

  1. 安裝 NuGet 程序包： Autofac.Extensions.DependencyInjection 7.1.0 、Autofac.Configuration 6.0.0
  2. 新建配置文件（指定接口和實現(xiàn)的對應(yīng)關(guān)系） autofac.json:
{
    "components":[
        {
            "type: "One.Services.TestServiceA,One",
            "services": [
                {
                    "type": "One.Services.ITestServiceA,One"
                }
            ],
            "instanceScope": "single-instance",
            "injectProperties": true
        },
        {
            "type: "One.Services.TestServiceB,One",
            "services": [
                {
                    "type": "One.Services.ITestServiceB,One"
                }
            ],
            "instanceScope": "single-instance",
            "injectProperties": true
        },
        {
            "type: "One.Services.TestServiceC,One",
            "services": [
                {
                    "type": "One.Services.ITestServiceC,One"
                }
            ],
            "instanceScope": "single-instance",
            "injectProperties": true
        },
        {
            "type: "One.Services.TestServiceD,One",
            "services": [
                {
                    "type": "One.Services.ITestServiceD,One"
                }
            ],
            "instanceScope": "single-instance",
            "injectProperties": true
        }
    ]   
}
  1. 讀取配置文件，完成服務(wù)對應(yīng)關(guān)系的注冊
var builder = new ContainerBuilder();
var config = new ConfigurationBuilder();
var configSource = new JsonConfigurationSource()
{
    Path = "Config/autofac.json",
    Optional = false,
    ReloadOnChange = true
};
config.Add(configSource); 
var configModule = new ConfigurationModule(config.Build());
builder.RegisterModule(configModule);
var container = builder.Build();

 // 獲取服務(wù)實例
 var testServiceA = container.Resolve<ITestServiceA>();
 var testServiceD = container.Resolve<ITestServiceD>();
 testServiceD.Show();
  1. 新建 ITestServiceA 的新版實現(xiàn)類 TestServiceUpdate 
public class TestServiceUpdate : ITestServiceA
{
    public TestServiceUpdate()
    {
        Console.WriteLine($"{this.GetType().Name} 被構(gòu)造了...");
    }

    public void Show()
    {
        Console.WriteLine($"This is a {this.GetType().Name} Instance...");
    }
}
  1. 通過修改配置文件 autofac.json 來實現(xiàn)快速實現(xiàn) ITestServiceA 的實現(xiàn)的重新定義：
{
    "components":[
        {
            "type: "One.Services.TestServiceUpdate,One",
            "services": [
                {
                    "type": "One.Services.ITestServiceA,One"
                }
            ],
            "instanceScope": "single-instance",
            "injectProperties": true
        },
        // ...

Autofac 整合 .NET 5 MVC

  1. 安裝 NuGet 程序包： Autofac.Extensions.DependencyInjection 7.1.0

  2. Program文件中指定 Autofac 工廠替換默認工廠：

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
              webBuilder.UseStartup<Startup>();
            }).UseServiceProviderFactory(new AutofacServiceProviderFactory());
  1. 在 Startup 類中增加 ConfigureContainer 方法：
    public void ConfigureContainer(ContainerBuilder builder)
    {
        builder.RegisterType<TestServiceA>().As<ITestServiceA>();
    }
  1. 通過控制器構(gòu)造函數(shù)注入，獲取實例
    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        private readonly ITestServiceA _serviceA;

        public ValuesController(ITestServiceA serviceA
        {
            _serviceA = serviceA;
        }

        [HttpGet]
        public IActionResult Get()
        {
            _serviceA.Show();
            return Ok();
        }
    }
  1. 使用 IServiceCollection 注冊的服務(wù)，將來也會交給 Autofac 管理
    public void ConfigureServices(IServiceCollection services)
    {
      #region IServiceCollection 注冊的服務(wù)，將來也會交給 Autofac 處理

      services.AddTransient<ITestServiceA, TestServiceA>();
      services.AddTransient<ITestServiceB, TestServiceB>();
      services.AddTransient<ITestServiceC, TestServiceC>();

      #endregion
    }

    public void ConfigureContainer(ContainerBuilder builder)
    {
        // builder.RegisterType<TestServiceA>().As<ITestServiceA>();
        // builder.RegisterType<TestServiceB>().As<ITestServiceB>();
        // builder.RegisterType<TestServiceC>().As<ITestServiceC>();
        builder.RegisterType<TestServiceD>().As<ITestServiceD>();
    }

Autofac 支持控制器屬性注入

控制器本身是一個類，它的實例其實是有 IControllerActivator 來創(chuàng)建的。

  1. 指定控制器的實例由容器來創(chuàng)建
    public void ConfigureServices(IServiceCollection services)
    {
        // ...
        
      #region 指定控制器的實例由容器來創(chuàng)建

      services.Replace(ServiceDescriptor.Transient<IControllerActivator, ServiceBasedControllerActivator>());

      #endregion
    }
  1. 注冊控制器的抽象和具體的關(guān)系
    public void ConfigureContainer(ContainerBuilder builder)
    {
        builder.RegisterType<TestServiceA>().As<ITestServiceA>().PropertiesAutowired();
        builder.RegisterType<TestServiceB>().As<ITestServiceB>();


        #region 注冊所有控制器的關(guān)系及控制器實例化所需要的組件

        var controllersTypesInAssembly = typeof(Startup).Assembly.GetExportedTypes()
            .Where(type => typeof(ControllerBase).IsAssignableFrom(type)).ToArray();

        builder.RegisterTypes(controllersTypesInAssembly)
            .PropertiesAutowired();

        #endregion
    }
  1. 在控制器內(nèi)定義屬性
    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        public ITestServiceA TestServiceA { get; set; }
        public ITestServiceB TestServiceB { get; set; }
        
        [HttpGet]
        public IActionResult Get()
        {
            TestServiceA.Show();
            TestServiceB.Show();
            return Ok();
        }
    }
  1. 擴展：自己控制哪些屬性需要做依賴注入(默認是讓控制器中的屬性都依賴注入)
    [AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
    public class AutowaredAttribute : Attribute { }

    public class PropertySelector : IPropertySelector
    {
        public bool InjectProperty(PropertyInfo propertyInfo, object instance)
        {
            return propertyInfo.CustomAttributes.Any(ca => ca.AttributeType == typeof(AutowaredAttribute));
        }
    }

    public void ConfigureContainer(ContainerBuilder builder)
    {
        builder.RegisterType<TestServiceA>().As<ITestServiceA>();
        builder.RegisterType<TestServiceB>().As<ITestServiceB>();

        #region 注冊所有控制器的關(guān)系及控制器實例化所需要的組件

        var controllersTypesInAssembly = typeof(Startup).Assembly.GetExportedTypes()
            .Where(type => typeof(ControllerBase).IsAssignableFrom(type)).ToArray();

        builder.RegisterTypes(controllersTypesInAssembly)
            .PropertiesAutowired(new PropertySelector());

        #endregion
    }

    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        [Autowared]
        public ITestServiceA TestServiceA { get; set; }
        
        public ITestServiceB TestServiceB { get; set; }
        
        [HttpGet]
        public IActionResult Get()
        {
            TestServiceA.Show();
            TestServiceB.Show();
            return Ok();
        }
    }

Autofac 單實例多實現(xiàn)

    public void ConfigureContainer(ContainerBuilder builder)
    {
        builder.RegisterType<TestServiceA>().As<ITestServiceA>();
        builder.RegisterType<TestServiceUpdate>().As<ITestServiceA>();
    }
  1. 如果多個實現(xiàn)同時注冊，則后注冊的實現(xiàn)就會覆蓋先注冊的實現(xiàn)，最后將返回最后一個注冊的實現(xiàn)。
  2. 如果多個實現(xiàn)同時注冊，可以通過一個 IEnumerable<實例> 來獲取到所有的實現(xiàn)。
        private readonly IEnumerable<ITestServiceA> _testServiceAs;

        public ValuesController(IEnumerable<ITestServiceA> testServiceAs)
        {
            _testServiceAs = testServiceAs;
        }
  1. 當(dāng)多個實現(xiàn)同時注冊后，可以通過以下方式繼續(xù)注冊 實例 的所有實現(xiàn)。從而可以在控制器中直接使用具體實現(xiàn)類作為實現(xiàn)。
    public void ConfigureContainer(ContainerBuilder builder)
    {
        builder.RegisterType<TestServiceA>().As<ITestServiceA>();
        builder.RegisterType<TestServiceUpdate>().As<ITestServiceA>();
        builder.RegisterSource(new AnyConcreteTypeNotAlreadyRegisteredSource(type => type.IsAssignableTo<ITestServiceA>()));
    }

        private readonly TestServiceA _testServiceA;
        private readonly TestServiceUpdate _testServiceUpdate;

        public ValuesController(TestServiceA testServiceA,TestServiceUpdate testServiceUpdate)
        {
            _testServiceA = testServiceA;
            _testServiceUpdate = testServiceUpdate;
        }
  1. 擴展：Autofac 的注冊邏輯可以通過 Module 來拆分管理。
    public class AutofacModule : Autofac.Module
    {
        protected override void Load(ContainerBuilder builder)
        {
            // base.Load(builder);
            builder.RegisterType<TestServiceA>().As<ITestServiceA>();
            builder.RegisterType<TestServiceUpdate>().As<ITestServiceA>();
            builder.RegisterSource(new AnyConcreteTypeNotAlreadyRegisteredSource(type => type.IsAssignableTo<ITestServiceA>()));
        }
    }

    public void ConfigureContainer(ContainerBuilder builder)
    {
        // builder.RegisterModule(new AutofacModule());
        builder.RegisterModule<AutofacModule>();
    }

Autofac 支持 AOP

AOP 面向切面編程，通過預(yù)編譯方式和運行期動態(tài)代理實現(xiàn)程序功能的統(tǒng)一維護的一種技術(shù)。Autofac 的AOP是通過 Castle（也是一個容器）項目的名為 Autofac.Extras.DynamicProxy 核心部分實現(xiàn)的，顧名思義其實現(xiàn)方式為動態(tài)代理。

  1. 安裝 NuGet 程序包： Castle.Core 4.4.1 、Autofac.Extras.DynamicProxy 6.0.0

  2. 新建自定義 AOP 攔截器

    public class CustomAutofacAop : IInterceptor
    {
        public void Intercept(IInvocation invocation)
        {
            {
                Console.WriteLine("方法執(zhí)行前...");
            }

            invocation.Proceed();

            {
                Console.WriteLine("方法執(zhí)行后...");
            }
        }
    }
  1. 在接口上標(biāo)記需要使用的攔截器
[Intercept(typeof(CustomAutofacAop))]
public interface ITestServiceA
{
    void Show();
}
  1. 注冊自定義攔截器，并允許實例接口使用攔截器
    public void ConfigureContainer(ContainerBuilder builder)
    {
        //builder.RegisterType<CustomAutofacAop>();
        builder.RegisterType(typeof(CustomAutofacAop));
        builder.RegisterType<TestServiceA>().As<ITestServiceA>();
        builder.RegisterType<TestServiceUpdate>().As<ITestServiceA>().EnableInterfaceInterceptors();
    }
  1. 在控制器中調(diào)用實例，即可成功執(zhí)行 AOP 攔截器
    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        private readonly TestServiceA _testServiceA;
        private readonly TestServiceUpdate _testServiceUpdate;

        public ValuesController(TestServiceA testServiceA,TestServiceUpdate testServiceUpdate)
        {
            _testServiceA = testServiceA;
            _testServiceUpdate = testServiceUpdate;
        }

        public IActionResult Get()
        {
            _testServiceA.Show();
            _testServiceUpdate.Show();
            return Ok();
        }
    }
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