【ASP.NET Core 依赖注入】在程序启动时获取服务实例

public class Program
{
    public static void Main(string[] args)
    {
        var host = CreateHostBuilder(args).Build();
        using (var scope = host.Services.CreateScope())
        {
            var services = scope.ServiceProvider;
            var context = services.GetRequiredService<ApplicationDbContext>();
            var logger = services.GetRequiredService<ILogger<Program>>();
        }
        host.Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder => 
                webBuilder.UseStartup<Startup>());
}