C#中IOC容器-Autofac的使用

什么是Ioc 把对象的统一创建交给第三方容器来创建 Inversion of Control，英文缩写为IoC，不是什么技术，而是一种设计思想。

Autofac容器初识

auto 是一款有优秀的IOC容器：那么如何使用？第三方容器

1. Nuget引入程序包autofac
   
2. 创建containerBuilder
3. 注册首先和实现的关系
4. Build一下，得到ConTainer容器
5. 用去获取服务实例
6. 使用服务

代码实现

                //构造函数注入
                //ContainerBuilder containerBuilder = new ContainerBuilder();
                //containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>();
                //containerBuilder.RegisterType<TestServiceB>().As<ITestServiceB>();
                //containerBuilder.RegisterType<TestServiceC>().As<ITestServiceC>();
                //IContainer container = containerBuilder.Build();
                //TestServiceB testServiceb = container.Resolve<TestServiceB>();//获取服务
                //testServiceb.Show();

Autofac多种注入方式

构造函数注入

           {
                ////构造函数注入
                //ContainerBuilder containerBuilder = new ContainerBuilder();
                //containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>();
                //containerBuilder.RegisterType<TestServiceB>().As<ITestServiceB>();
                //containerBuilder.RegisterType<TestServiceC>().As<ITestServiceC>();
                //IContainer container = containerBuilder.Build();
                //ITestServiceB testServiceb = container.Resolve<ITestServiceB>();//获取服务
                //testServiceb.Show();
            }

属性注入

          //{
            //    ContainerBuilder containerBuilder = new ContainerBuilder();
            //    containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>();
            //    containerBuilder.RegisterType<TestServiceB>().As<ITestServiceB>();
            //    containerBuilder.RegisterType<TestServiceC>().As<ITestServiceC>();
            //    containerBuilder.RegisterType<TestServiceD>().As<ITestServiceD>().PropertiesAutowired();
            //    IContainer container = containerBuilder.Build();
            //    ITestServiceD testServiceD = container.Resolve<ITestServiceD>();//获取服务
            //    testServiceD.Show();
            //}

方法注入

 //{
            //    ContainerBuilder containerBuilder = new ContainerBuilder();
            //    containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>();
            //    //containerBuilder.RegisterType<TestServiceB>().As<ITestServiceB>();
            //    containerBuilder.RegisterType<TestServiceB>().OnActivated(e => e.Instance.SetService(e.Context.Resolve<ITestServiceA>())).As<ITestServiceB>();
            //    containerBuilder.RegisterType<TestServiceC>().As<ITestServiceC>();
            //    containerBuilder.RegisterType<TestServiceD>().As<ITestServiceD>().PropertiesAutowired();
            //    IContainer container = containerBuilder.Build();
            //    ITestServiceB testServiceb = container.Resolve<ITestServiceB>();//获取服务
            //    testServiceb.Show();
            //}

Autofac生命周期

1. 瞬时生命周期 ---每一期获取对象都是一个全新的实例（默认的生命）

{ //瞬时生命周期 ---每一期获取对象都是一个全新的实例（默认的生命）
                    //ContainerBuilder containerBuilder = new ContainerBuilder();
                    //containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>().InstancePerDependency();
                    //IContainer container = containerBuilder.Build();
                    //ITestServiceA testServiceA = container.Resolve<ITestServiceA>();//获取服务
                    //ITestServiceA testServiceA1 = container.Resolve<ITestServiceA>();//获取服务
                    //Console.WriteLine(object.ReferenceEquals(testServiceA, testServiceA1));
                }

1. 单例生命周期---在整个进程中，对象永远都是同一个实例（SingleInstance）

 { //单例生命周期---在整个进程中，对象永远都是同一个实例（SingleInstance）
                    //ContainerBuilder containerBuilder = new ContainerBuilder();
                    //containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>().SingleInstance();
                    //IContainer container = containerBuilder.Build();
                    //ITestServiceA testServiceA = container.Resolve<ITestServiceA>();//获取服务
                    //ITestServiceA testServiceA1 = container.Resolve<ITestServiceA>();//获取服务
                    //Console.WriteLine(object.ReferenceEquals(testServiceA, testServiceA1));
                }

1. 每个生命周期范围一个实例--同一个生命周期范围内是同一个实例，不同的生命周期范围，实例不一样； (InstancePerLifetimeScope)

                   { //每个生命周期范围一个实例--同一个生命周期范围内是同一个实例，不同的生命周期范围，实例不一样；  (InstancePerLifetimeScope)
                       //ContainerBuilder containerBuilder = new ContainerBuilder();
                       //containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>().InstancePerLifetimeScope();
                       //IContainer container = containerBuilder.Build();
   
                       //ITestServiceA testServiceA15 = null;
                       //ITestServiceA testServiceA16 = null;
                       //using (var scope1 = container.BeginLifetimeScope()) //生命周期范围
                       //{
                       //    ITestServiceA testServiceA11 = scope1.Resolve<ITestServiceA>();
                       //    ITestServiceA testServiceA12 = scope1.Resolve<ITestServiceA>();
                       //    Console.WriteLine(object.ReferenceEquals(testServiceA11, testServiceA12));
                       //    testServiceA15 = testServiceA12;
                       //}
   
                       //using (var scope1 = container.BeginLifetimeScope())
                       //{
                       //    ITestServiceA testServiceA13 = scope1.Resolve<ITestServiceA>();
                       //    ITestServiceA testServiceA14 = scope1.Resolve<ITestServiceA>();
                       //    Console.WriteLine(object.ReferenceEquals(testServiceA13, testServiceA14));
                       //    testServiceA16 = testServiceA14;
                       //}
                       //Console.WriteLine(object.ReferenceEquals(testServiceA15, testServiceA16));
                   }
   
   

2. 每个【匹配生命周期范围一个实例】（InstancePerMatchingLifetimeScope（名称））

 { //每个【匹配生命周期范围一个实例】（InstancePerMatchingLifetimeScope（名称））
                    //ContainerBuilder containerBuilder = new ContainerBuilder();
                    //containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>().InstancePerMatchingLifetimeScope("Zhaoxi");

                    //IContainer container = containerBuilder.Build();

                    //ITestServiceA testServiceA15 = null;
                    //ITestServiceA testServiceA16 = null;
                    //using (var scope1 = container.BeginLifetimeScope("Zhaoxi"))
                    //{
                    //    ITestServiceA testServiceA11 = scope1.Resolve<ITestServiceA>();
                    //    using (var scope2 = scope1.BeginLifetimeScope())
                    //    {
                    //        ITestServiceA testServiceA12 = scope2.Resolve<ITestServiceA>();
                    //        Console.WriteLine(object.ReferenceEquals(testServiceA11, testServiceA12));
                    //    }
                    //    testServiceA15 = testServiceA11;
                    //}

                    //using (var scope1 = container.BeginLifetimeScope("Zhaoxi"))
                    //{
                    //    ITestServiceA testServiceA13 = scope1.Resolve<ITestServiceA>();
                    //    using (var scope2 = scope1.BeginLifetimeScope())
                    //    {
                    //        ITestServiceA testServiceA14 = scope2.Resolve<ITestServiceA>();
                    //        Console.WriteLine(object.ReferenceEquals(testServiceA13, testServiceA14));
                    //    }

                    //    testServiceA16 = testServiceA13;
                    //}
                    //Console.WriteLine(object.ReferenceEquals(testServiceA15, testServiceA16));
                }

1. 每个请求一个实例(InstancePerRequest) ---mvc中

    ////每个请求一个实例(InstancePerRequest)
                       //ContainerBuilder containerBuilder = new ContainerBuilder();
                       //containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>().InstancePerRequest();
                       //IContainer container = containerBuilder.Build(); 
                       //ITestServiceA testServiceA11 = container.Resolve<ITestServiceA>();
                       //ITestServiceA testServiceA12 = container.Resolve<ITestServiceA>();
                       //Console.WriteLine(object.ReferenceEquals(testServiceA11, testServiceA12));
   
   
   

Autofac支持配置文件

Nuget引入支持配置文件：

Autofac. Extensions.DependencyInjection Aputofac.Configuration Autofac

              {
                //ContainerBuilder containerBuilder = new ContainerBuilder();
                //// 就可以在这里写入Autofac注入的各种 
                //{
                //    //读取配置文件,把配置关系装载到ContainerBuilder
                //    IConfigurationBuilder config = new ConfigurationBuilder();
                //    IConfigurationSource autofacJsonConfigSource = new JsonConfigurationSource()
                //    {
                //        Path = "CfgFile/autofac.json",
                //        Optional = false,//boolean,默认就是false,可不写
                //        ReloadOnChange = true,//同上
                //    };
                //    config.Add(autofacJsonConfigSource);
                //    ConfigurationModule module = new ConfigurationModule(config.Build());
                //    containerBuilder.RegisterModule(module);
                //}
                //IContainer container = containerBuilder.Build();
                //ITestServiceA testServiceA = container.Resolve<ITestServiceA>();
                //ITestServiceD testServiceD = container.Resolve<ITestServiceD>();
                //testServiceD.Show();
            }

Autofac整合

Autofac是一个第三方容器

1. 指定Autofac工厂替换默认工厂,Program指定

Program中CreateHostBuilder的hostbuilder添加.UseServiceProviderFactory(new AutofacServiceProviderFactory());

var hostbuilder = Host.CreateDefaultBuilder(args) //创建一个默认的主机builder
                //.ConfigureLogging(loggingBuilder=> 
                //{  //配置log4Net配置文件的读取
                //    loggingBuilder.AddLog4Net("CfgFile/log4net.Config");
                //}) 
                .ConfigureWebHostDefaults(webBuilder =>  //配置成一个默认的Web主机
                {
                    webBuilder.UseStartup<Startup>(); //使用Startup文件来实现配置

                }).UseServiceProviderFactory(new AutofacServiceProviderFactory()); 

1. 在Startup类增加ConfigureContainer方法，注册关系

    public void ConfigureContainer(ContainerBuilder containerBuilder)
   {
       containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>();
   }
   
   

   Autofac支持控制器属性注入

   控制器是一个类, 控制器的实例其实是IControllerActivator来创建的;

   var controllersTypesInAssembly = typeof (Startup) .Assembly . GetExportedTypes()
   .Where(type => typeof (ControllerBase) .ISAssi gnab1eFrom(type)). ToArray();
   builder .RegisterTypes (control1ersTypes InAssemb1y) . PropertiesAutowired(new AutowiredpropertySelector();
   
   

1. 得让控制器使用容器来获取实例;
2. 注册控制器抽象和具体的关系

2. 在控制器内定义属性

3. 扩展，自己控制究竟哪些属性需要做依赖注入

//指定控制器实例让容器来创建
           services.Replace(ServiceDescriptor.Transient<IControllerActivator, ServiceBasedControllerActivator>());

Autofac抽象多实现的问题

1. 一个抽象多个实例，都注册了，通过构造函数用抽象类型来获取实例，哪个后面注册就获取到哪一个;覆盖型;
2. 个抽象多个实例，都注册了,可以通过一个IEnumerable<抽象> ,当做构造函数参数,可以获取到所有注册的具体的实例;
3. 注册一个抽象的多个实例资源，如下方式注册，可以在控制器的构造函数中，使用具体实现类型作为参数类型,可以匹配到不同到具体 类型实例

ontainerBuilder.RegisterSource (new AnyConcreteTypeNotAlreadyRegisteredsource(t =>
t. IsAssignab1eTo<IestServiceA>());

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