从.net Core中的appsettings.json获取价值

Question

不知道我在这里缺少什么，但是我无法从.net核心应用程序中的appsettings.json获取值。我有我的appsettings.json为：

{

    "AppSettings": {

        "Version": "One"

    }

}

启动：

public class Startup

{

    private IConfigurationRoot _configuration;

    public Startup(IHostingEnvironment env)

    {

        _configuration = new ConfigurationBuilder()

    }

    public void ConfigureServices(IServiceCollection services)

    {

      //Here I setup to read appsettings        

      services.Configure<AppSettings>(_configuration.GetSection("AppSettings"));

    }

}

模型：

public class AppSettings

{

    public string Version{ get; set; }

}

控制器：

public class HomeController : Controller

{

    private readonly AppSettings _mySettings;

    public HomeController(IOptions<AppSettings> settings)

    {

        //This is always null

        _mySettings = settings.Value;

    }

}

_mySettings始终为null。我在这里缺少什么吗？