WPF CommandParameter的使用

<Window x:Class="Wpf180706.Window5"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Window5" Height="300" Width="300">
    <Window.CommandBindings>
        <CommandBinding Command="New" Executed="New_Execute" CanExecute="New_CanExecute"></CommandBinding>
    </Window.CommandBindings>
    <Grid>
        <StackPanel>
            <TextBox Name="txt"></TextBox>
            <Button Name="newTeacher" Command="New" CommandParameter="Teacher">NewTeacher</Button>
            <Button Name="newStudent"  Command="New" CommandParameter="Student">NewStudent</Button>
            <TextBlock Name="msg"></TextBlock>
        </StackPanel>
    </Grid>

</Window>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace Wpf180706
{
    /// <summary>
    /// Interaction logic for Window5.xaml
    /// </summary>
    public partial class Window5 : Window
    {
        public Window5()
        {
            InitializeComponent();
        }

        private void New_Execute(object sender, ExecutedRoutedEventArgs e)
        {
            msg.Text = e.Parameter.ToString();
        }

        private void New_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            if (string.IsNullOrEmpty(txt.Text))
            {
                e.CanExecute = false;
            }
            else
            {
                e.CanExecute = true;
            }
        }
    }
}