.NET中的WPF是什么？如何使用MVVM模式来构建桌面应用？

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

using System.ComponentModel;
using System.Runtime.CompilerServices;

public class MainViewModel : INotifyPropertyChanged
{
    private string _name;
    public string Name
    {
        get => _name;
        set
        {
            _name = value;
            OnPropertyChanged();
        }
    }

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

<Window x:Class="WpfApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <StackPanel>
        <TextBox Text="{Binding Name, UpdateSourceTrigger=PropertyChanged}" />
        <TextBlock Text="{Binding Name}" FontSize="20" />
    </StackPanel>
</Window>

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        DataContext = new MainViewModel();
    }
}

public class MainViewModel : INotifyPropertyChanged
{
    private ICommand _sayHelloCommand;
    public ICommand SayHelloCommand =>
        _sayHelloCommand ?? (_sayHelloCommand = new RelayCommand(SayHello));

    private void SayHello()
    {
        MessageBox.Show($"Hello, {Name}!");
    }

    // ... 其他属性和事件
}

<Button Content="Say Hello" Command="{Binding SayHelloCommand}" />