用WPF写一段多视图切换管理的代码

以下是一个简单的多视图切换管理的示例代码：

MainWindow.xaml：

<Window x:Class="MultiViewSwitching.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:MultiViewSwitching"
        Title="Multi-View Switching" Height="300" Width="400">
    <Window.Resources>
        <DataTemplate x:Key="View1Template">
            <local:View1/>
        </DataTemplate>
        <DataTemplate x:Key="View2Template">
            <local:View2/>
        </DataTemplate>
    </Window.Resources>
    <Grid>
        <ContentControl x:Name="ViewContainer" Content="{Binding CurrentView}" />
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Bottom" Margin="0,20,0,0">
            <Button Content="View 1" Command="{Binding SwitchToView1Command}"/>
            <Button Content="View 2" Command="{Binding SwitchToView2Command}"/>
        </StackPanel>
    </Grid>
</Window>

MainWindow.xaml.cs：

using System.ComponentModel;
using System.Windows;
using System.Windows.Input;

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

    public class MainViewModel : INotifyPropertyChanged
    {
        private object currentView;
        public object CurrentView
        {
            get { return currentView; }
            set
            {
                currentView = value;
                OnPropertyChanged(nameof(CurrentView));
            }
        }

        public ICommand SwitchToView1Command { get; }
        public ICommand SwitchToView2Command { get; }

        public MainViewModel()
        {
            SwitchToView1Command = new RelayCommand(o => CurrentView = new View1());
            SwitchToView2Command = new RelayCommand(o => CurrentView = new View2());
            CurrentView = new View1();
        }

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

    public class RelayCommand : ICommand
    {
        private readonly Action<object> execute;
        private readonly Predicate<object> canExecute;

        public RelayCommand(Action<object> execute, Predicate<object> canExecute = null)
        {
            this.execute = execute;
            this.canExecute = canExecute;
        }

        public bool CanExecute(object parameter)
        {
            return canExecute == null || canExecute(parameter);
        }

        public void Execute(object parameter)
        {
            execute(parameter);
        }

        public event EventHandler CanExecuteChanged;
        public void RaiseCanExecuteChanged()
        {
            CanExecuteChanged?.Invoke(this, EventArgs.Empty);
        }
    }
}

View1.xaml和View2.xaml可以是任何自定义的用户控件。在此示例中，它们非常简单，只包含一个TextBlock和一个Button：

View1.xaml：

<UserControl x:Class="MultiViewSwitching.View1"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="400">
    <Grid>
        <TextBlock Text="View 1"/>
        <Button Content="Switch to View 2" Click="SwitchToView2"/>
    </Grid>
</UserControl>

View2.xaml：

<UserControl x:Class="MultiViewSwitching.View2"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="400">
    <Grid>
        <TextBlock Text="View 2"/>
        <Button Content="Switch to View 1" Click="SwitchToView1"/>
    </Grid>
</UserControl>

最后，MainViewModel类中使用了一个简单的RelayCommand类来实现SwitchToView1Command和SwitchToView2Command的ICommand接口。这个RelayCommand类使用了委托来实现Execute和CanExecute方法。Execute方法将会调用传入的委托，而CanExecute方法将会检查传入的委托是否为null，或者如果不为null，它是否返回true。RaiseCanExecuteChanged方法用于在CanExecuteChanged事件发生时通知WPF重新评估ICommand的CanExecute方法。