获取非UI对象以响应WPF命令绑定

        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:WpfApp1"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
   <Window.CommandBindings>
       <CommandBinding Command="ApplicationCommands.Open"
                          Executed="CommandBinding_Executed"
                          CanExecute="CommandBinding_CanExecute" />
    </Window.CommandBindings>
    <Grid>
       <TextBox x:Name="TextBox1"
                 CommandTarget="{Binding ElementName=MainWindow}"
                 Command="ApplicationCommands.Open"
                 HorizontalAlignment="Left"
                 Margin="10,10,0,0"
                 TextWrapping="Wrap"
                 VerticalAlignment="Top"
                 Width="200" />
    </Grid>
</Window>