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？