IServiceCollection - 依赖注入？ 在哪里可用？

Question

I am learning ASP.NET core though a pluralsite video. The fellow in the video tells me I can add a "service" as a singleton or as a transient, by registering it in Startup.ConfigureServices.

public class Startup {

    public Startup() {
    }

    public IConfiguration Configuration { get; set; }

    // This method gets called by the runtime. Use this method to add services to the container.
    // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
    public void ConfigureServices(IServiceCollection services) {

        // Register the Greeter as an IGreeter and have the ASP.NET framework register it to be available to anyone who wants an IGreeter
        // Dependency injection?
        services.AddSingleton<IGreeter, Greeter>();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, IGreeter greeter) {
        if (env.IsDevelopment()) {
            app.UseDeveloperExceptionPage();
        }

        app.Run(async (context) => {
            var greeting = greeter.GetGreeting();
            await context.Response.WriteAsync(greeting);
        });
    }
}

He wasn't very clear about who is instantiating it, what its life time is, and where it is available. Can someone fill in those details for me?

Is this doing what I would have done with a dependency injection framework like Autofac, but ASP.NET Core has it built in? Or is this different?

Answer 1

who is instantiating it, what its lifetime is, and where it is available.

The framework will instantiate the service with the lifetime you specified during registering it in your DI-Container. All your registered services are available in the projects that have referenced from the main project which contains your DI-Container.

Is this doing what I would have done with a dependency injection framework like Autofac, but ASP.NET Core has it built in? Or is this different?

Everything is the same as other DI Containers like AutoFac . DI is done using ASP.NET Core's built-in DI Container called Microsoft.Extensions.DependencyInjection