.NET MAUI ContentView中如何解决依赖注入问题？

我试过某方法但无效，GetService返回null。

声明：这是最小可复现示例（MRE），请勿建议不使用服务的解决方案。

我需要在ContentView中访问已添加到依赖注入容器的单例服务，希望LuckyNumberText通过该服务生成随机数。但ContentView的构造函数必须无参，无法直接注入依赖。

以下是完整的最小可复现代码：

App.xaml #

<?xml version = "1.0" encoding = "UTF-8" ?>
<Application xmlns="http://schemas.microsoft.com/dotnet/2021/maui" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:local="clr-namespace:MauiMRE" x:Class="MauiMRE.App">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="Resources/Styles/Colors.xaml" />
                <ResourceDictionary Source="Resources/Styles/Styles.xaml" />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>

App.xaml.cs #

namespace MauiMRE;
public partial class App : Application
{
    public static IServiceProvider Services => ServiceProvider.Current;
    public App()
    {
        InitializeComponent();
        MainPage = new AppShell();
    }
}

AppShell.xaml #

<?xml version="1.0" encoding="UTF-8" ?>
<Shell x:Class="MauiMRE.AppShell" xmlns="http://schemas.microsoft.com/dotnet/2021/maui" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:local="clr-namespace:MauiMRE" Shell.FlyoutBehavior="Disabled">
    <ShellContent Title="Home" ContentTemplate="{DataTemplate local:MainPage}" Route="MainPage" />
</Shell>

AppShell.xaml.cs #

namespace MauiMRE;
public partial class AppShell : Shell
{
    public AppShell()
    {
        InitializeComponent();
    }
}

MainPage.xaml #

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="MauiMRE.MainPage" xmlns:local="clr-namespace:MauiMRE" >
    <local:MyContentView>
    </local:MyContentView>
</ContentPage>

MainPage.xaml.cs #

namespace MauiMRE;
public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();
    }
}

MauiProgram.cs #

using Microsoft.Extensions.Logging;
namespace MauiMRE;
public static class MauiProgram
{
    public static MauiApp CreateMauiApp()
    {
        var builder = MauiApp.CreateBuilder();
        builder
            .UseMauiApp<App>()
            .ConfigureFonts(fonts =>
            {
                fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
            });
#if DEBUG
        builder.Logging.AddDebug();
#endif        
        builder.Services.AddSingleton<MyContentView>();
        builder.Services.AddSingleton<MyContentViewModel>();
        builder.Services.AddSingleton<MyService>();
        return builder.Build();
    }
}

MyContentView.xaml #

<?xml version="1.0" encoding="utf-8" ?>
<ContentView xmlns="http://schemas.microsoft.com/dotnet/2021/maui" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="MauiMRE.MyContentView">
    <VerticalStackLayout>
        <Label Text="{Binding LuckyNumberText}" VerticalOptions="Center" HorizontalOptions="Center" />
    </VerticalStackLayout>
</ContentView>

MyContentView.xaml.cs #

namespace MauiMRE;
public partial class MyContentView : ContentView
{
    public MyContentView()
    {
        InitializeComponent();
        BindingContext = new MyContentViewModel();
    }
}

MyContentViewModel.cs #

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace MauiMRE;
public class MyContentViewModel
{
    public MyContentViewModel()
    {
        var service = ServiceProvider.GetService<MyService>(); 
        var result = service.RandomInt(); // 执行到这里前就崩溃了
    }
    public string LuckyNumberText
    {
        get
        {
            return $"Lucky number: {1}";
        }
    }
}

MyService.cs #

namespace MauiMRE
{
    public static class ServiceProvider
    {
        public static T GetService<T>()
        {
            var current = Current; // 能执行
            return current.GetService<T>(); // 这里崩溃
        }
        public static IServiceProvider Current
            =>
#if WINDOWS10_0_17763_0_OR_GREATER
                MauiWinUIApplication.Current.Services;
#elif ANDROID
                MauiApplication.Current.Services; // 应该是这里崩溃
#else
                null;
#endif
    }
}

内容的提问来源于stack exchange，提问作者infinitezero