.NET MAUI(WinUI3)自定义URI协议重复启动实例问题求助

针对你遇到的Windows端自定义URI协议启动新实例、无法触发OnAppLinkRequestReceived的问题，可通过以下步骤解决：

1. 实现单实例与协议激活事件转发 #

在Windows项目的Platforms/Windows/App.xaml.cs中，利用Windows App SDK的AppInstance实现单实例逻辑，并捕获协议激活事件：

using Microsoft.Maui;
using Microsoft.Windows.AppLifecycle;
using Windows.ApplicationModel.Activation;
using Windows.UI.Xaml;
using System;

namespace YourAppNamespace.WinUI;

public partial class App : MauiWinUIApplication
{
    private AppInstance? _currentInstance;

    public App()
    {
        InitializeComponent();
        SetupSingleInstanceAndProtocolHandling();
    }

    protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();

    private void SetupSingleInstanceAndProtocolHandling()
    {
        // 注册唯一实例标识
        _currentInstance = AppInstance.FindOrRegisterInstanceForKey("DayPlanner_InstanceKey");

        if (!_currentInstance.IsCurrent)
        {
            // 转发激活请求到已有实例，退出新实例
            AppInstance.GetCurrent().RedirectActivationTo(_currentInstance);
            Environment.Exit(0);
            return;
        }

        // 订阅实例激活事件
        _currentInstance.Activated += OnInstanceActivated;
    }

    private void OnInstanceActivated(object? sender, AppActivationArguments args)
    {
        if (args.Kind != ActivationKind.Protocol) return;
        
        var protocolArgs = args.Data as ProtocolActivatedEventArgs;
        if (protocolArgs?.Uri == null) return;

        // 手动触发MAUI的AppLink事件
        var mauiApp = (Microsoft.Maui.Controls.App)MauiContext!.Services.GetRequiredService<IApplication>();
        mauiApp.OnAppLinkRequestReceived(protocolArgs.Uri);

        // 激活当前窗口
        Window.Current?.Activate();
    }

    // 处理首次启动时的协议激活
    protected override void OnLaunched(LaunchActivatedEventArgs args)
    {
        base.OnLaunched(args);

        if (args.Kind == ActivationKind.Protocol)
        {
            var protocolArgs = args as ProtocolActivatedEventArgs;
            if (protocolArgs?.Uri != null)
            {
                var mauiApp = (Microsoft.Maui.Controls.App)MauiContext!.Services.GetRequiredService<IApplication>();
                mauiApp.OnAppLinkRequestReceived(protocolArgs.Uri);
            }
        }
    }
}

2. 确保MAUI端正确处理AppLink事件 #

在MAUI项目根目录的App.xaml.cs中，重写OnAppLinkRequestReceived以处理令牌参数：

using Microsoft.Maui.Controls;
using System;
using System.Web; // 需添加System.Web引用，或用其他方式解析QueryString

namespace YourAppNamespace;

public partial class App : Application
{
    public App()
    {
        InitializeComponent();
        MainPage = new MainPage();
    }

    protected override void OnAppLinkRequestReceived(Uri uri)
    {
        // 解析令牌参数
        var queryParams = HttpUtility.ParseQueryString(uri.Query);
        var token = queryParams["token"];
        var refreshToken = queryParams["refreshToken"];

        // 执行你的认证逻辑，比如保存令牌、跳转页面等
        if (!string.IsNullOrEmpty(token))
        {
            // 示例：保存令牌到本地存储
            Preferences.Set("AuthToken", token);
            Preferences.Set("RefreshToken", refreshToken);
            
            // 跳转到主页或认证后的页面
            MainPage = new MainPage();
        }

        base.OnAppLinkRequestReceived(uri);
    }
}

3. 检查Package.appxmanifest配置 #

确保协议扩展处于正确的层级（在<Application>节点内），并补充必要的显示名称：

<Package ...>
  <Applications>
    <Application Id="App" Executable="$targetnametoken$.exe" EntryPoint="YourAppNamespace.WinUI.App">
      <!-- 其他配置 -->
      <Extensions>
        <uap:Extension Category="windows.protocol">
          <uap:Protocol Name="dayplanner">
            <uap:DisplayName>Day Planner 协议</uap:DisplayName>
          </uap:Protocol>
        </uap:Extension>
      </Extensions>
    </Application>
  </Applications>
</Package>

4. 测试前的必要操作 #

• 卸载电脑上已安装的旧版本应用，避免配置残留
• 重新部署MAUI应用到Windows平台
• 测试时使用dayplanner://?token=xyz&refreshToken=abc链接，确认不会启动新实例，且令牌参数能被正确捕获

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