WPF框架中异步、多线程、高性能、零拷贝技术的应用示例

WPF框架中异步、多线程、高性能与零拷贝技术应用示例

一、异步编程在WPF中的应用

1. 异步数据加载（避免UI冻结）

// ViewModel中的异步数据加载示例
public class MainViewModel : INotifyPropertyChanged
{
    private ObservableCollection<string> _items;
    public ObservableCollection<string> Items
    {
        get => _items;
        set { _items = value; OnPropertyChanged(); }
    }

    public async Task LoadDataAsync()
    {
        // 显示加载状态
        IsLoading = true;
        
        try
        {
            // 模拟耗时操作
            var data = await Task.Run(() =>
            {
                // 这里可以是数据库查询、文件读取或网络请求
                Thread.Sleep(2000); // 模拟耗时操作
                return new List<string> { "Item1", "Item2", "Item3" };
            });
            
            Items = new ObservableCollection<string>(data);
        }
        catch (Exception ex)
        {
            // 错误处理
            MessageBox.Show($"加载数据失败: {ex.Message}");
        }
        finally
        {
            IsLoading = false;
        }
    }

    private bool _isLoading;
    public bool IsLoading
    {
        get => _isLoading;
        set { _isLoading = value; OnPropertyChanged(); }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

// XAML中的使用
<Window x:Class="WpfAsyncDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="异步加载示例" Height="350" Width="525">
    <Grid>
        <StackPanel VerticalAlignment="Center" HorizontalAlignment="Center">
            <ProgressBar IsIndeterminate="{Binding IsLoading}" Width="200" Height="10"/>
            <Button Content="加载数据" Click="LoadData_Click" Margin="0,10"/>
            <ListBox ItemsSource="{Binding Items}" Height="200"/>
        </StackPanel>
    </Grid>
</Window>

// 代码后台
public partial class MainWindow : Window
{
    private readonly MainViewModel _viewModel = new MainViewModel();
    
    public MainWindow()
    {
        InitializeComponent();
        DataContext = _viewModel;
    }
    
    private async void LoadData_Click(object sender, RoutedEventArgs e)
    {
        await _viewModel.LoadDataAsync();
    }
}

2. 异步文件I/O操作

// 异步读取大文件
public async Task<string> ReadLargeFileAsync(string filePath)
{
    using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read, 4096, useAsync: true))
    using (var reader = new StreamReader(stream))
    {
        return await reader.ReadToEndAsync();
    }
}

// 异步写入文件
public async Task WriteLargeFileAsync(string filePath, string content)
{
    using (var stream = new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.None, 4096, useAsync: true))
    using (var writer = new StreamWriter(stream))
    {
        await writer.WriteAsync(content);
    }
}

二、多线程技术在WPF中的应用

1. 使用BackgroundWorker（传统方式）

// 在ViewModel中使用BackgroundWorker
public class BackgroundWorkerViewModel : INotifyPropertyChanged
{
    private readonly BackgroundWorker _worker