昨天.NET Core 3.0 正式发布，创建一个项目运行后发现：原来使用的Autofac在ConfigureServices返回IServiceProvider的这种写法已经不再支持。当然Autofac官方也给出了示例。

.NET Core 本身内置DI，我决定不再使用Autofac，就使用原生DI，拓展IServiceCollection实现一个IocManager,

实现批量注入，静态获取实例功能。

一、Autofac官方文档

Program Class

Hosting changed in ASP.NET Core 3.0 and requires a slightly different integration. This is for ASP.NET Core 3+ and the .NET Core 3+ generic hosting support:

public class Program
{
  public static void Main(string[] args)
  {
    // ASP.NET Core 3.0+:
    // The UseServiceProviderFactory call attaches the
    // Autofac provider to the generic hosting mechanism.
    var host = Host.CreateDefaultBuilder(args)
        .UseServiceProviderFactory(new AutofacServiceProviderFactory())
        .ConfigureWebHostDefaults(webHostBuilder => {
          webHostBuilder
            .UseContentRoot(Directory.GetCurrentDirectory())
            .UseIISIntegration()
            .UseStartup<Startup>();
        })
        .Build();

    host.Run();
  }
}

Startup Class

In your Startup class (which is basically the same across all the versions of ASP.NET Core) you then use ConfigureContainer to access the Autofac container builder and register things directly with Autofac.

public class Startup
{
  public Startup(IHostingEnvironment env)
  {
    // In ASP.NET Core 3.0 env will be an IWebHostingEnvironment, not IHostingEnvironment.
    var builder = new ConfigurationBuilder()
        .SetBasePath(env.ContentRootPath)
        .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
        .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
        .AddEnvironmentVariables();
    this.Configuration = builder.Build();
  }

  public IConfigurationRoot Configuration { get; private set; }

  public ILifetimeScope AutofacContainer { get; private set; }

  // ConfigureServices is where you register dependencies. This gets
  // called by the runtime before the ConfigureContainer method, below.
  public void ConfigureServices(IServiceCollection services)
  {
    // Add services to the collection. Don't build or return
    // any IServiceProvider or the ConfigureContainer method
    // won't get called.
    services.AddOptions();
  }

  // ConfigureContainer is where you can register things directly
  // with Autofac. This runs after ConfigureServices so the things
  // here will override registrations made in ConfigureServices.
  // Don't build the container; that gets done for you. If you
  // need a reference to the container, you need to use the
  // "Without ConfigureContainer" mechanism shown later.
  public void ConfigureContainer(ContainerBuilder builder)
  {
      builder.RegisterModule(new AutofacModule());
  }

  // Configure is where you add middleware. This is called after
  // ConfigureContainer. You can use IApplicationBuilder.ApplicationServices
  // here if you need to resolve things from the container.
  public void Configure(
    IApplicationBuilder app,
    ILoggerFactory loggerFactory)
  {
    // If, for some reason, you need a reference to the built container, you
    // can use the convenience extension method GetAutofacRoot.
    this.AutofacContainer = app.ApplicationServices.GetAutofacRoot();

    loggerFactory.AddConsole(this.Configuration.GetSection("Logging"));
    loggerFactory.AddDebug();
    app.UseMvc();
  }
}

二、IocManager实现

1、创建IocManager

public interface IIocManager
{
    IServiceProvider ServiceProvider { get; set; }
}

public class IocManager : IIocManager
{
    static Io