public interface ITestService
{string ShowMsg();
}

public class TestService: ITestService
{public string ShowMsg(){return "test123";}
}

Autofac
Autofac.Extensions.DependencyInjection

public IServiceProvider ConfigureServices(IServiceCollection services)
{services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);// Add Autofacvar containerBuilder = new ContainerBuilder();containerBuilder.RegisterModule<AutofacModule>();containerBuilder.Populate(services);var container = containerBuilder.Build();return new AutofacServiceProvider(container);
}

public class AutofacModule: Module
{protected override void Load(ContainerBuilder builder){builder.RegisterType<TestService>().As<ITestService>();　　　　 //...........}
}

public IServiceProvider ConfigureServices(IServiceCollection services)
{services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);// Add Autofacvar containerBuilder = new ContainerBuilder();//containerBuilder.RegisterModule<AutofacModule>();
　　 //自动注册该程序集下的所有接口//netcore_autofac 为程序集命名空间//InstancePerLifetimeScope：同一个Lifetime生成的对象是同一个实例//SingleInstance：单例模式，每次调用，都会使用同一个实例化的对象；每次都用同一个对象；//InstancePerDependency：默认模式，每次调用，都会重新实例化对象；每次请求都创建一个新的对象；containerBuilder.RegisterAssemblyTypes(Assembly.Load("netcore_autofac")).AsImplementedInterfaces().InstancePerLifetimeScope();containerBuilder.Populate(services);var container = containerBuilder.Build();return new AutofacServiceProvider(container);
}