UWP模板10和服务密度注入(MVVM)不是WPF

问题描述

我花了两个多星期的时间搜索google，bing，堆栈溢出和msdn文档，试图弄清楚如何对我正在开发的移动应用程序进行适当的依赖注入.需要明确的是，我每天都在Web应用程序中进行DI.我不需要关于什么，谁以及为什么DI很重要的速成班.我知道这是事实，并且一直在拥抱它.

I have spent over two weeks searching google, bing, stack overflow, and msdn docs trying to figure out how to do a proper dependency injection for a mobile app that I am developing. To be clear, I do DI every day in web apps. I do not need a crash course on what, who, and why DI is important. I know it is, and am always embracing it.

我需要了解的是它在移动应用程序世界中的工作原理，尤其是UWP Template 10移动应用程序.

What I need to understand is how this works in a mobile app world, and in particular a UWP Template 10 Mobile app.

从过去，在.net/Asp应用程序中，我可以"RegisterType(new XYZ).Singleton()等等" {请原谅语法；只是一个示例}.在.netcore中，该方法几乎相同，但进行了一些语法更改.

From my past, in a .net/Asp app I can "RegisterType(new XYZ).Singleton() blah" {please forgive syntax; just an example} in App_Start.ConfigureServices. This works almost identical in .netcore, granted some syntactic changes.

我的问题是，现在我正在尝试提供我的api到需要摘要我的IXYZ服务的UWP应用.我绝不认为他们每次都应该更新"一个实例.必须有一种方法可以将其注入到UWP侧的容器中.而且我觉得我在此过程中缺少了非常一些简单的东西.

My problem is now I am trying to provide my api is going to an UWP app that needs to digest my IXYZ service. By no means do I think that they should "new" up an instance every time. There has to be a way to inject this into a container on the UWP side; and I feel I am missing something very simple in the process.

这是我的代码:

App.xaml.cs

App.xaml.cs

public override async Task OnStartAsync(StartKind startKind, IActivatedEventArgs args)
    {
        // TODO: add your long-running task here

        //if (args.Kind == ActivationKind.LockScreen)
        //{

        //}
        RegisterServices();
        await NavigationService.NavigateAsync(typeof(Views.SearchCompanyPage));

    }

public static IServiceProvider Container { get; private set; }

private static void RegisterServices()
{
    var services = new ServiceCollection();
    services.AddSingleton<IXYZ, XYZ>();
    Container = services.BuildServiceProvider();
}

MainPage.xaml.cs:

MainPage.xaml.cs:

public MainPage()
{
   InitializeComponent();
   NavigationCacheMode = NavigationCacheMode.Enabled;
}

MainPageViewModel:

MainPageViewModel:

public class MainPageViewModel : ViewModelBase
{
    private readonly IXYZ _xyz;
    public MainPageViewModel(IXYZ xyz)
    {
        //Stuff
        _xyz= xyz;
    }

}

我现在得到错误: XAML MainPage ... ViewModel类型无法构造.为了用XAML构造，类型不能是抽象的，接口嵌套的泛型或结构，并且必须具有公共的默认构造函数.

I now get the error:XAML MainPage...ViewModel type cannot be constructed. In order to be constructed in XAML, a type cannot be abstract, interface nested generic or a struct, and must have a public default constructor.

我愿意使用任何品牌的IoC容器，但我需要的是一个如何在UWP应用程序中正确使用DI进行服务的示例.关于DI的99.9％的问题与视图(即Prism?)有关，而不仅仅是服务(即DataRepo；又名API/DataService)的简单DI.

I am willing to use any brand of IoC Container, but what I need is an example of how to properly use DI for services in a UWP app. 99.9% of questions about DI is about Views (i.e. Prism?) not just a simple DI for a service (i.e. DataRepo; aka API/DataService).

再次，我觉得我缺少明显的东西，需要向正确的方向轻推.有人可以给我看一个示例项目，基本代码或关于我不应该成为程序员的基础鞭打...请不要这样做(我不知道我的自我是否可以接受).

Again, I feel I am missing something obvious and need a nudge in the right direction. Can somebody show me an example project, basic code, or a base flogging on how I should not be a programmer...please don't do that (I don't know if my ego could take it).

推荐答案

您可以尝试像ASP.NET一样使用Microsoft.Hosting.Extensions，Xamarin.Forms上有一个 James Montemagno ，也可以在我拥有的UWP中使用尝试，它完美地工作.您必须更改某些部分才能使其正常工作.

You can try to Microsoft.Hosting.Extensions just like ASP.NET, there's an implementation on Xamarin.Forms by James Montemagno, as well it can be used in UWP I have tried and it works perfectly. You have to change some parts in order to get it working.

public static class Startup
{
    public static IServiceProvider ServiceProvider { get; set; }
    public static void Init()
    {
        StorageFolder LocalFolder = ApplicationData.Current.LocalFolder;
        var configFile = ExtractResource("Sales.Client.appsettings.json", LocalFolder.Path);

        var host = new HostBuilder()
                    .ConfigureHostConfiguration(c =>
                    {
                        // Tell the host configuration where to file the file (this is required for Xamarin apps)
                        c.AddCommandLine(new string[] { $"ContentRoot={LocalFolder.Path}" });

                        //read in the configuration file!
                        c.AddJsonFile(configFile);
                    })
                    .ConfigureServices((c, x) =>
                    {
                        // Configure our local services and access the host configuration
                        ConfigureServices(c, x);
                    }).
                    ConfigureLogging(l => l.AddConsole(o =>
                    {
                        //setup a console logger and disable colors since they don't have any colors in VS
                        o.DisableColors = true;
                    }))
                    .Build();

        //Save our service provider so we can use it later.
        ServiceProvider = host.Services;
    }

    static void ConfigureServices(HostBuilderContext ctx, IServiceCollection services)
    {
        //ViewModels
        services.AddTransient<HomeViewModel>();
        services.AddTransient<MainPageViewModel>();
    }

    static string ExtractResource(string filename, string location)
    {
        var a = Assembly.GetExecutingAssembly();

        using (var resFilestream = a.GetManifestResourceStream(filename))
        {
            if (resFilestream != null)
            {
                var full = Path.Combine(location, filename);

                using (var stream = File.Create(full))
                {
                    resFilestream.CopyTo(stream);
                }
            }
        }
        return Path.Combine(location, filename);
    }
}

也可以注入ViewModel .

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