wpf创建命令代码，实现一个清空的命令

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
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 wpf控件互相绑定
{
    /// <summary>
    /// Window1.xaml 的交互逻辑
    /// </summary>
    public partial class Window1 : Window
    {

        public Window1()
        {
            InitializeComponent();
            InitCommand();

            if (string.IsNullOrEmpty(txt.Text))  //判断是否为空
            {
                this.btn1.IsEnabled = false;
            }
            else

            {
                this.btn1.IsEnabled = true;
            }

        }
        RoutedCommand rc = new RoutedCommand("clear", typeof(Window1));
        public void InitCommand()
        {
            btn1.Command = rc;
            rc.InputGestures.Add(new KeyGesture(Key.C,ModifierKeys.Alt));  //定义快捷键
            btn1.CommandTarget = txt;

            CommandBinding cb=new CommandBinding ()
            {
                Command =rc,
            };

            cb.CanExecute+=cb_CanExecute;
            cb.Executed += cb_Executed;

            sp.CommandBindings.Add(cb);
        }

        private void cb_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            if (string.IsNullOrEmpty(txt.Text))
            {
                e.CanExecute = false;
            }
            else
            {
                e.CanExecute = true;
            }
            e.Handled = true;
        }
        void cb_Executed(object sender, ExecutedRoutedEventArgs e)
        {
            txt.Clear();
            e.Handled = true;
        }

        private void Button_Click_1(object sender, RoutedEventArgs e)
        {

        }

    }
}