如何在 Asp.Net MVC 6 中检索 AppSettings 配置？

Question

假设我正在使用新的 DepencyInjection 框架在新的 ASP.Net/vNext 中配置我的类和依赖项。

如何使用，如何获取我的预定义配置设置？

    public void ConfigureServices(IServiceCollection services)
    {
        // Add Application settings to the services container.
        services.Configure<AppSettings>(Configuration.GetSubKey("AppSettings"));

        // Add EF services to the services container.
        services.AddEntityFramework()
            .AddSqlServer()
            .AddDbContext<ApplicationDbContext>(options =>
                options.UseSqlServer(Configuration["Data:DefaultConnection:ConnectionString"]));
        // Add Identity services to the services container.
        services.AddIdentity<ApplicationUser, IdentityRole>()
            .AddEntityFrameworkStores<ApplicationDbContext>()
            .AddDefaultTokenProviders();

        // Configure the options for the authentication middleware.
        // You can add options for Google, Twitter and other middleware as shown below.
        // For more information see http://go.microsoft.com/fwlink/?LinkID=532715
        services.Configure<FacebookAuthenticationOptions>(options =>
        {
            options.AppId = Configuration["Authentication:Facebook:AppId"];
            options.AppSecret = Configuration["Authentication:Facebook:AppSecret"];
        });

        services.Configure<MicrosoftAccountAuthenticationOptions>(options =>
        {
            options.ClientId = Configuration["Authentication:MicrosoftAccount:ClientId"];
            options.ClientSecret = Configuration["Authentication:MicrosoftAccount:ClientSecret"];
        });

        // Add MVC services to the services container.
        services.AddMvc();

        services.AddSingleton(a =>
        {
            //AppSettings settingsModel = ?? //GET CONFIGURATION SETTINGS FILLED 

            // TECHNICAL ARTIFICE TO RETRIEVE CURRENT SETTINGS
            //var settingsModel = new AppSettings();
            //var config = Configuration.GetSubKey("AppSettings");
            //foreach (var item in typeof(AppSettings).GetProperties().Where(b => b.CanWrite))
            {
                //item.SetValue(settingsModel, config.Get(item.Name));
            }

            return new FooService(settingsModel);
        });

        //Uncomment the following line to add Web API services which makes it easier to port Web API 2 controllers.
        //You will also need to add the Microsoft.AspNet.Mvc.WebApiCompatShim package to the 'dependencies' section of project.json.
        services.AddWebApiConventions();
    }

Answer 1

您可以通过在其构造函数中注入IOptions<AppSettings> DI 服务来获取 FooService 中的 AppSettings。

IOptions<> 接口是选项模型的一部分，用于在您的应用程序中访问 POCO 样式设置（例如：您的 AppSettings）。 在上面的示例中，像 services.Configure<AppSettings>( 和 services.Configure<FacebookAuthenticationOptions>(options => 这样的调用实际上注册了 DI 服务，而这些 DI 服务又被称为 OptionsManager 的 DI 服务在解析 IOptions<> 的请求时使用。

例子：

public class FooService
{
    private readonly AppSettings _settings;

    public FooService(IOptions<AppSettings> options)
    {
        _settings = options.Options;
    }

    ....
    ....
}