.NET MAUI Android端Google登录中Web Authenticator的正确用法

我按照.NET MAUI Web Authenticator官方文档配置，但文档缺少回调URL的关键信息。按文档要求使用myapp://作为回调URL时，WebAuthenticatorActivity报错：

You must subclass the WebAuthenticatorCallbackActivity and create an IntentFilter for it which matches your callbackUrl.

我参考了第三方辅助库、相关视频及GitHub示例，其中用myapp作为回调URL，但Uri类报错：

Invalid URI: The format of the URI could not be determined.

我尝试组合配置：Web Authenticator回调URL用myapp://，WebAuthenticatorActivity用myapp，虽能运行但Google控制台不允许将myapp://或myapp设为重定向URL。改用https://mysite/signin-google作为Google控制台重定向URL后，登录流程在Google从浏览器重定向回应用时失败，报错：

This mysite page can't by found. No webpage was found for the web address: https://mysite/signin-google

现需明确以下三个配置项的正确取值：

• Web Authenticator的回调URL
• WebAuthenticatorActivity的配置值
• Google控制台的重定向URL

文件 MauiProgram.cs #

using CommunityToolkit.Maui;
using FertilizerFarm.Helpers;
using FertilizerFarm.Services;
using FertilizerFarm.View;
using Refit;
using Telerik.Maui.Controls.Compatibility;

namespace FertilizerFarm;
public static class Constants
{

    public const string BaseUrl = "https://mysite/mobileauth/";
    public const string CallbackScheme = "myapp://";
}
public static class MauiProgram
{
    public static MauiApp CreateMauiApp()
    {
        var builder = MauiApp.CreateBuilder();
        builder
             .UseTelerik()
            .UseMauiApp<App>()
            .UseMauiCommunityToolkit()
            .ConfigureFonts(fonts =>
            {
                fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
                fonts.AddFont("telerikfontexamples.ttf", "TelerikFontExamples");
            });
        builder.Services.AddSingleton<IConnectivity>(Connectivity.Current)
        .AddSingleton(WebAuthenticator.Default)
        .AddSingleton(SecureStorage.Default)
        .AddRefitClient<IUserProfileService>()
        .AddSingleton<AuthService>()
        .AddSingleton<JWTService>()
        .AddTransient<LoginViewModel>()
        .AddTransient<Login>();

        return builder.Build();
    }
    public static IServiceCollection AddRefitClient<T>(this IServiceCollection services)
      where T : class
    {
        services.AddSingleton(sp =>
        {
            var settings = new RefitSettings
            {
                AuthorizationHeaderValueGetter = () => sp.GetRequiredService<ISecureStorage>().GetAsync("access_token")
            };
            return RestService.For<T>(Constants.BaseUrl, settings);
        });
        return services;
    }
}

文件 WebAuthenticatorCallbackActivity.cs #

using Android.App;
using Android.Content;
using Android.Content.PM;

namespace FertilizerFarm;

[Activity(NoHistory = true, LaunchMode = LaunchMode.SingleTop, Exported = true)]
[IntentFilter(new[] { Intent.ActionView },
                  Categories = new[] { Intent.CategoryDefault, Intent.CategoryBrowsable },
                  DataScheme = CALLBACK_SCHEME)]
public class WebAuthenticatorActivity : Microsoft.Maui.Authentication.WebAuthenticatorCallbackActivity
{
    const string CALLBACK_SCHEME = "myapp";
}

文件 LoginViewModel.cs #

[RelayCommand]
async Task SocialLogin()
{
    try
    {
        var result = await _webAuthenticator.AuthenticateAsync(new WebAuthenticatorOptions
        {
            CallbackUrl = new Uri($"{Constants.CallbackScheme}"),
            Url = new Uri(Constants.BaseUrl + "google")
        });

        await _storage.SetAsync("access_token", result.AccessToken);

        using var response = await _userProfile.GetProfileClaims();
        if (response.IsSuccessStatusCode)
        {
            Claims.Clear();
            var claims = response.Content.Select(x => $"{x.Key}: {x.Value}");
            foreach (var claim in claims)
                Claims.Add(claim);
        }
    }
    catch (Exception ex)
    {
    }
}

内容的提问来源于stack exchange，提问作者Pretorius