如何在MVVM中注册IHttpClientFactory

Question

我正在使用MVVM编写一个WPF应用程序，我最初的想法是使用静态Httpclient从多个设备抽象数据，存在一个与静态Httpclient有关的DNS问题。那么，如果我要使用IHttpClientFactory，我应该如何设置呢？

我所读到的是我的MainViewModel构造函数需要这样做：

 public class MainViewModel : ViewModelBase
{
    /// <summary>
    /// Initializes a new instance of the MainViewModel class.
    /// </summary>
    /// 

    private readonly IHttpClientFactory httpClientFactory;
   
    public MainViewModel(IHttpClientFactory httpClientFactory)
    {
        this.httpClientFactory = httpClientFactory;
        var client = httpClientFactory.CreateClient();
    }

}

我这里有两个问题：

( a)我无法在MainViewModel上注册ViewLocator

 public ViewModelLocator()
    {
        ServiceLocator.SetLocatorProvider(() => SimpleIoc.Default);

        if (ViewModelBase.IsInDesignModeStatic)
        {
            // Create design time view services and models
           // SimpleIoc.Default.Register<IDataService, DesignDataService>();
        }
        else
        {
        ///    // Create run time view services and models
            //SimpleIoc.Default.Register<IDataService, DataService>();
       }

         SimpleIoc.Default.Register<IHttpClientFactory, MainViewModel>();  
        
    }

     public MainViewModel Main
    {
        get
        {
            return ServiceLocator.Current.GetInstance< MainViewModel>(); --> Error
            "ServiceLocator.ActivationException: 'Type not found in cache: "
        }
    }

( b)启动时是否低于要求，我应该在哪里使用此方法？

 private void ConfigureServices(IServiceCollection services)
    {
        // ...

        services.AddHttpClient();

        services.AddTransient(typeof(MainWindow));  ---> ? valid for MVVM?
    }

或者有人在WPF中使用过IHttpClientFactory和MVVM？

谢谢

西蒙

Answer 1

您可以使用Microsoft.Extensions.Hosting中的Microsoft.Extensions.Hosting创建ViewModelLocator中的DI容器。

public class ViewModelLocator
{
    private readonly IServiceProvider _serviceProvider;

    public ViewModelLocator()
    {
        _serviceProvider = new HostBuilder()
            .ConfigureServices(ConfigureServices)
            .Build()
            .Services;
    }

    public MainViewModel Main =>
        _serviceProvider.GetService<MainViewModel>();

    private void ConfigureServices(IServiceCollection services)
    {
        services.AddHttpClient();
        services.AddSingleton<MainViewModel>();
    }
}