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Avalonia+ReactiveUI+Sourcegenerators实现异步命令

news 2025/10/14 7:18:02

1、必要的包引用

    <PackageReference Include="Avalonia" Version="11.3.6" /><PackageReference Include="Avalonia.ReactiveUI" Version="11.3.6" /><PackageReference Include="ReactiveUI.SourceGenerators" Version="2.4.1">

2、ViewModel (使用 ReactiveUI Source Generators)

using ReactiveUI;
using ReactiveUI.SourceGenerators;
using System;
using System.Threading;
using System.Threading.Tasks;namespace AvaRea.ViewModels
{public partial class TestCmdViewModel: ViewModelBase{private IObservable<bool> _canExecute;private IObservable<bool> _canCancel;private  CancellationTokenSource _cancellationTokenSource = new();[Reactive] private string _status  = "就绪";[Reactive] private bool _isExecuting = false;[ObservableAsProperty] private bool _isCancelEnabled =>!_isExecuting;[ReactiveCommand(CanExecute = nameof(_canExecute))]private async void ExecuteAsync(CancellationToken cancellationToken){IsExecuting = true;Status = "任务执行中...";try{// 创建新的 CancellationTokenSource 并链接命令的cancellationToken_cancellationTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);// 模拟异步工作for (int i = 0; i <= 100; i++){// 检查取消请求_cancellationTokenSource.Token.ThrowIfCancellationRequested();Status = $"进度: {i}%";await Task.Delay(100, cancellationToken); // 模拟工作}Status = "任务完成!";}catch (OperationCanceledException){Status = "任务已取消";}finally{IsExecuting = false;IsExecuting = false;_cancellationTokenSource?.Dispose();_cancellationTokenSource = null;}}[ReactiveCommand(CanExecute =nameof(_canCancel))]private void CancelExecution(){_cancellationTokenSource?.Cancel();Status = "正在取消...";}public TestCmdViewModel(){Status = "初始化状态";_canExecute= this.WhenAnyValue(x => x.IsExecuting, x =>!x);_canCancel = this.WhenAnyValue(x => x.IsExecuting);}}
}

3、View

<Windowx:Class="AvaRea.TestCmdView"xmlns="https://github.com/avaloniaui"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:d="http://schemas.microsoft.com/expression/blend/2008"xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"xmlns:vm="clr-namespace:AvaRea.ViewModels"Title="测试异步命令"Width="300"Height="200"d:DesignHeight="200"d:DesignWidth="300"x:DataType="vm:TestCmdViewModel"mc:Ignorable="d"><StackPanel Margin="20" Spacing="10"><TextBlock FontSize="16" Text="{Binding Status}" /><StackPanel Orientation="Horizontal" Spacing="10"><ButtonCommand="{Binding ExecuteAsyncCommand}"Content="开始执行" /><ButtonBackground="Red"Command="{Binding CancelExecutionCommand}"Content="取消"Foreground="White" /></StackPanel></StackPanel>
</Window>

4、App.axaml

<Application xmlns="https://github.com/avaloniaui"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"x:Class="AvaRea.App"RequestedThemeVariant="Default"><!-- "Default" ThemeVariant follows system theme variant. "Dark" or "Light" are other available options. --><Application.Styles><FluentTheme /></Application.Styles>
</Application>

5、App.axaml.cs

using Avalonia;
using Avalonia.Controls.ApplicationLifetimes;
using Avalonia.Markup.Xaml;
using AvaRea.ViewModels;namespace AvaRea;public partial class App : Application
{public override void Initialize(){AvaloniaXamlLoader.Load(this);}public override void OnFrameworkInitializationCompleted(){if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop){desktop.MainWindow = new TestCmdView{DataContext = new TestCmdViewModel()};}else if (ApplicationLifetime is ISingleViewApplicationLifetime singleViewPlatform){singleViewPlatform.MainView = new TestCmdView{DataContext = new TestCmdViewModel()};}base.OnFrameworkInitializationCompleted();}
}

6、Program.cs

using System;using Avalonia;
using Avalonia.ReactiveUI;namespace AvaRea.Desktop;class Program
{// Initialization code. Don't use any Avalonia, third-party APIs or any// SynchronizationContext-reliant code before AppMain is called: things aren't initialized// yet and stuff might break.[STAThread]public static void Main(string[] args) => BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);// Avalonia configuration, don't remove; also used by visual designer.public static AppBuilder BuildAvaloniaApp()=> AppBuilder.Configure<App>().UsePlatformDetect().WithInterFont().LogToTrace().UseReactiveUI();
}

7、主要特点

CancellationToken 传递: ReactiveCommand 会自动传递 CancellationToken;
取消检查: 在异步方法中定期检查 cancellationToken.ThrowIfCancellationRequested();
状态管理: 使用 IsExecuting 属性并利用ReactiveUI响应式编程特点和Sourcegenerators简化代码的功能控制 UI 状态和命令可用性，无需再axaml代码中进行绑定;
资源清理: 使用 using 语句或 finally 块确保 CancellationTokenSource 被正确清理。