WPF（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.Navigation;
using System.Windows.Shapes;

namespace WpfCommand
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            InitializeCommand();
        }

        // 声明命令
        private RoutedCommand clearCmd = new RoutedCommand("Clear", typeof(MainWindow));


        private void InitializeCommand()
        {
            // 命令源
            this.btn.Command = clearCmd;
            this.clearCmd.InputGestures.Add(new KeyGesture(Key.C,ModifierKeys.Alt));

            // 命令目标
            this.btn.CommandTarget = this.txt;

            // 命令绑定
            CommandBinding cb = new CommandBinding();
            cb.Command = this.clearCmd;
            cb.CanExecute += new CanExecuteRoutedEventHandler(cb_CanExecute);
            cb.Executed += new ExecutedRoutedEventHandler(cb_Execute);

            // 安置到外围控件上
            this.stackpanel.CommandBindings.Add(cb);
        }

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

            args.Handled = true;
        }

        private void cb_Execute(object sender, ExecutedRoutedEventArgs args)
        {
            this.txt.Clear();
            args.Handled = true;
        }
    }
}

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优化代码段

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.Navigation;
using System.Windows.Shapes;

namespace WpfCommand
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            InitializeCommand();
        }

        // 声明命令
        private RoutedCommand clearCmd = new RoutedCommand("Clear", typeof(MainWindow));


        private void InitializeCommand()
        {
            // 命令源
            this.btn.Command = clearCmd;
            this.clearCmd.InputGestures.Add(new KeyGesture(Key.C, ModifierKeys.Alt));

            //// 命令目标
            //this.btn.CommandTarget = this.txt;

            //// 命令绑定
            //CommandBinding cb = new CommandBinding();
            //cb.Command = this.clearCmd;
            //cb.CanExecute += new CanExecuteRoutedEventHandler(cb_CanExecute);
            //cb.Executed += new ExecutedRoutedEventHandler(cb_Execute);

            // 安置到外围控件上
            this.CommandBindings.Add(new CommandBinding(clearCmd,cb_Execute,cb_CanExecute));
        }

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

            args.Handled = true;
        }

        private void cb_Execute(object sender, ExecutedRoutedEventArgs args)
        {
            this.txt.Clear();
            args.Handled = true;
        }
    }
}