在ASP.Net Core 3.1通用主机“Worker Service”应用程序中使用Autofac

Question

在一个ASP.Net Core应用程序中，使用以下方法配置Autofac非常简单：

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();
  }
}

public class Startup
{
  // Omitting extra stuff so you can see the important part...
  public void ConfigureServices(IServiceCollection services)
  {
    // Add controllers as services so they'll be resolved.
    services.AddMvc().AddControllersAsServices();
  }

  public void ConfigureContainer(ContainerBuilder builder)
  {
    // If you want to set up a controller for, say, property injection
    // you can override the controller registration after populating services.
    builder.RegisterType<MyController>().PropertiesAutowired();
  }
}

然而在一个通用主机中，Worker类没有任何内置的支持ConfigureServices和ConfigureContainer。

如何在非ASP.Net Core应用程序中为通用主机启用相同的功能？

- Satyajit

Answer 1

通用主机构建器确实内置了对ConfigureContainer和ConfigureServices的支持。

var host = Host.CreateDefaultBuilder(args)
    .UseServiceProviderFactory(new AutofacServiceProviderFactory())
    .ConfigureContainer<ContainerBuilder>(builder => {

        builder.RegisterType<MyDependencyType>();

        //...
    })
    .ConfigureServices(services => {

        services.AddHostedService<Worker>();

        //...
    })
    .ConfigureWebHostDefaults(webHostBuilder => {
        webHostBuilder
            .UseContentRoot(Directory.GetCurrentDirectory())
            .UseIISIntegration()
            .UseStartup<Startup>();
    })
    .Build();

host.Run();

参考 .NET 通用主机

- Nkosi

---

在这种情况下，您会如何调用UseStartup？ - Maulik Modi

@MaulikModi 请查看此处的文档。它将在ConfigureWebHostDefaults扩展中被调用。 - Nkosi

Answer 2

在 @Nkosi 的优秀答案基础上补充一点：

如果您还需要从 ConfigureContainer 访问某些配置数据，请使用 (hostContext, services) 重载：

    // ...    
    .ConfigureContainer<ContainerBuilder>((hostContext, builder) =>
          {
             IConfiguration configuration = hostContext.Configuration;
             var myDbConnectionString = configuration.GetConnectionString("MyDbConnection");

             builder.RegisterType<MyDependencyType>();
          }))
    // ... 

- brunochaina