public class A : D
{

    public A(B b)
    {
        // do something   
    }
    C c = new C();
}

public async Task Get(int id)
{
    IAdvertisementServices advertisementServices = new AdvertisementServices();
    return await advertisementServices.Query(d => d.Id == id);
}

 　　　　[HttpGet("{id}", Name = "Get")]
        public async Task Get(int id)
        {
            IAdvertisementServices advertisementServices = new AdvertisementServices();//需要引用两个命名空间Blog.Core.IServices;Blog.Core.Services;

            return await advertisementServices.Query(d => d.Id == id);
        }

 　　　　public IServiceProvider ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
            #region 配置信息
            //Blog.Core.Repository.BaseDBConfig.ConnectionString = Configuration.GetSection("AppSettings:SqlServerConnection").Value;
            #endregion

            #region Swagger
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new Info
                {
                    Version = "v0.1.0",
                    Title = "Blog.Core API",
                    Description = "框架说明文档",
                    TermsOfService = "None",
                    Contact = new Swashbuckle.AspNetCore.Swagger.Contact { Name = "Blog.Core", Email = "Blog.Core@xxx.com", Url = "https://www.jianshu.com/u/94102b59cc2a" }
                });

                //就是这里

                #region 读取xml信息
                var basePath = PlatformServices.Default.Application.ApplicationBasePath;
                var xmlPath = Path.Combine(basePath, "Blog.Core.xml");//这个就是刚刚配置的xml文件名
                var xmlModelPath = Path.Combine(basePath, "Blog.Core.Model.xml");//这个就是Model层的xml文件名
                c.IncludeXmlComments(xmlPath, true);//默认的第二个参数是false，这个是controller的注释，记得修改
                c.IncludeXmlComments(xmlModelPath);
                #endregion

                #region Token绑定到ConfigureServices
                //添加header验证信息
                //c.OperationFilter();
                var security = new Dictionarystring, IEnumerablestring>> { { "Blog.Core", new string[] { } }, };
                c.AddSecurityRequirement(security);
                //方案名称“Blog.Core”可自定义，上下一致即可
                c.AddSecurityDefinition("Blog.Core", new ApiKeyScheme
                {
                    Description = "JWT授权(数据将在请求头中进行传输) 直接在下框中输入{token}\"",
                    Name = "Authorization",//jwt默认的参数名称
                    In = "header",//jwt默认存放Authorization信息的位置(请求头中)
                    Type = "apiKey"
                }); 
                #endregion


            });
            #endregion

            #region Token服务注册
            services.AddSingleton(factory =>
             {
                 var cache = new MemoryCache(new MemoryCacheOptions());
                 return cache;
             });
            services.AddAuthorization(options =>
            {
                options.AddPolicy("Admin", policy => policy.RequireClaim("AdminType").Build());//注册权限管理，可以自定义多个
            });
            #endregion

            #region AutoFac
            
            //实例化 AutoFac  容器   
            var builder = new ContainerBuilder();

            //注册要通过反射创建的组件
            builder.RegisterType().As();

            //将services填充到Autofac容器生成器中
            builder.Populate(services);

            //使用已进行的组件登记创建新容器
            var ApplicationContainer = builder.Build();

            #endregion

            return new AutofacServiceProvider(ApplicationContainer);//第三方IOC接管 core内置DI容器
        }

 　　　　 IAdvertisementServices advertisementServices;
        /// 

        /// 构造函数
        /// 
        /// 
        public BlogController(IAdvertisementServices advertisementServices)
        {
            this.advertisementServices = advertisementServices;
        }


 　　　　[HttpGet("{id}", Name = "Get")]
        public async Task Get(int id)
        {
            //IAdvertisementServices advertisementServices = new AdvertisementServices();//需要引用两个命名空间Blog.Core.IServices;Blog.Core.Services;

            return await advertisementServices.Query(d => d.Id == id);
        }

 　　　　　　var builder = new ContainerBuilder();

            //注册要通过反射创建的组件
            //builder.RegisterType().As();

            var assemblysServices = Assembly.Load("Blog.Core.Services");
            builder.RegisterAssemblyTypes(assemblysServices).AsImplementedInterfaces();//指定已扫描程序集中的类型注册为提供所有其实现的接口。
            var assemblysRepository = Assembly.Load("Blog.Core.Repository");
            builder.RegisterAssemblyTypes(assemblysRepository).AsImplementedInterfaces();

            //将services填充到Autofac容器生成器中
            builder.Populate(services);

            //使用已进行的组件登记创建新容器
            var ApplicationContainer = builder.Build();

　　 public class BaseServices : IBaseServiceswhere TEntity : class, new()
    {
        //public IBaseRepository baseDal = new BaseRepository();
        public IBaseRepository baseDal;//通过在子类的构造函数中注入，这里是基类，不用构造函数
  　　　　//...  
　　 }


    public class AdvertisementServices : BaseServices, IAdvertisementServices
    {
        IAdvertisementRepository dal;
        public AdvertisementServices(IAdvertisementRepository dal)
        {
            this.dal = dal;
            base.baseDal = dal;
        }       
    }

//1. 定义一个服务，包含一个方法
public class PeopleService
{
    public string Run(string m) { return m; }
}
//2. 写一个扩展方法用来注入服务，与直接在ConfigureServices返回是一个道理
namespace Haos.Develop.CoreTest
{
    public static class Extension
    {
        public static IServiceCollection AddTestService(this IServiceCollection service)
        {
            return service.AddScoped(factory => new PeopleService());
        }
    }
}

//3. 回到Startup类中找到ConfigureServices方法添加如下代码
public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc(); 
    services.AddTestService();//将上边的方法注入
}

//4.我们可以采用构造函数方式来注入和直接获取
public PeopleService People;
public HomeController(PeopleService people)//构造函数
{
    People = people;
}
public JsonResult Test()
{
    People.Run("111"); 
    return Json("");
}