WPF基本命令系统使用

<Window x:Class="CommandTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        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:local="clr-namespace:CommandTest"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid x:Name="aGrid">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="236*"/>
            <ColumnDefinition Width="559*"/>
        </Grid.ColumnDefinitions>
        <Button x:Name="abutton" Content="Button" HorizontalAlignment="Left" Margin="186.046,62,0,0" VerticalAlignment="Top" Width="75" Grid.Column="1"/>
        <TextBox x:Name="aTextBox" HorizontalAlignment="Left" Height="23" Margin="186.046,126,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120" Grid.Column="1"/>

    </Grid>
</Window>

 public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            initializeCommand();
        }

        //声明并定义命令
        private RoutedCommand clearCmd = new RoutedCommand("clear", typeof(MainWindow));

        private void initializeCommand() {
            //把命令赋值给发送者并指定快捷键
            abutton.Command = clearCmd;
            clearCmd.InputGestures.Add(new KeyGesture(Key.C, ModifierKeys.Alt));

            //指定命令目标
            abutton.CommandTarget = aTextBox;

            //创建命令关联
            CommandBinding cb = new CommandBinding();
            cb.Command = clearCmd;
            cb.CanExecute += new CanExecuteRoutedEventHandler(cb_canExecute);
            cb.Executed += new ExecutedRoutedEventHandler(cb_execute);

            //把命令关联在外围控件上
            aGrid.CommandBindings.Add(cb);
        }

        //探测命令是否被执行时，该命令被调用 
        void cb_canExecute(object sender, CanExecuteRoutedEventArgs e) {
            if (string.IsNullOrEmpty(aTextBox.Text))
            {
                e.CanExecute = false;
            }
            else {
                e.CanExecute = true;
            }

            //避免继续向上传降低程序性能
            e.Handled = true;
        }

        //当命令到达目标后，此方法被调用
        void cb_execute(object sender, ExecutedRoutedEventArgs e) {
            aTextBox.Clear();

            //避免继续向上传降低程序性能
            e.Handled = true;
        }
    }
}