如果在TextBox中键入新字符,如何才能进行数据绑定更新？

我正在学习WPF中的绑定,现在我已经陷入了(希望)简单的问题.

我有一个简单的FileLister类,您可以在其中设置Path属性,然后它将在您访问FileNames属性时为您提供文件列表.这是班级:

class FileLister:INotifyPropertyChanged {
    private string _path = "";

    public string Path {
        get {
            return _path;
        }
        set {
            if (_path.Equals(value)) return;
            _path = value;
            OnPropertyChanged("Path");
            OnPropertyChanged("FileNames");
        }
    }

    public List<String> FileNames {
        get {
            return getListing(Path);
        }
    }

    private List<string> getListing(string path) {
        DirectoryInfo dir = new DirectoryInfo(path);
        List<string> result = new List<string>();
        if (!dir.Exists) return result;
        foreach (FileInfo fi in dir.GetFiles()) {
            result.Add(fi.Name);
        }
        return result;
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string property) …

我正在尝试了解如何使用RoutedCommands.我的印象是,如果我没有在Button上指定CommandTarget,任何聚焦元素都将收到命令.但由于某种原因,它不起作用.这是不起作用的xaml:

<Window x:Class="WpfTest11_Commands2.MainWindow"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            Title="MainWindow" Height="350" Width="525">
    <Grid>
        <TextBox Height="177" HorizontalAlignment="Left"
            Margin="12,12,0,0" Name="textBox1" VerticalAlignment="Top" Width="233" AcceptsReturn="True" />
        <TextBox Height="177" HorizontalAlignment="Left"
            Margin="258,12,0,0" Name="textBox2" VerticalAlignment="Top" Width="233" AcceptsReturn="True" />
        <Button Content="Cut"
                    Height="23" HorizontalAlignment="Left" Margin="12,195,0,0" Name="button1" VerticalAlignment="Top" Width="75"
                    Command="ApplicationCommands.Cut"/>
    </Grid>
</Window>

如果我将CommandTarget添加到Button它可以工作,但仅适用于当然指定的文本框.

<Window x:Class="WpfTest11_Commands2.MainWindow"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            Title="MainWindow" Height="350" Width="525">
    <Grid>
        <TextBox Height="177" HorizontalAlignment="Left" Margin="12,12,0,0" Name="textBox1" VerticalAlignment="Top" Width="233" AcceptsReturn="True" />
        <TextBox Height="177" HorizontalAlignment="Left" Margin="258,12,0,0" Name="textBox2" VerticalAlignment="Top" Width="233" AcceptsReturn="True" />
        <Button Content="Cut"
                    Height="23" HorizontalAlignment="Left" Margin="12,195,0,0" Name="button1" VerticalAlignment="Top" Width="75"
                    Command="ApplicationCommands.Cut"
                    CommandTarget="{Binding ElementName=textBox1}"/>
    </Grid>
</Window>

如何使任何聚焦元素接收命令？

谢谢!