一、概述

• 创建命令类
• 声明命令实例
• 指定命令源
• 指定命令目标
• 设置命令关联

二、使用

2.1 例子

   public Window28()
        {
            InitializeComponent();
            InitializeCommand();
        }
        //声明并定义命令
        private RoutedCommand rouutedCommand = new RoutedCommand("Clear",typeof(Window28));
        private void InitializeCommand()
        {
            //把命令赋值给命令源,并定义快捷键
            this.btn1.Command = rouutedCommand;
            this.rouutedCommand.InputGestures.Add(new KeyGesture(Key.C, ModifierKeys.Alt));
            //指定命令目标
            this.btn1.CommandTarget = txtA;

            //创建命令关联
            CommandBinding commandBinding = new CommandBinding();
            commandBinding.Command = rouutedCommand;//只关注与rouutedCommand相关的命令
            commandBinding.CanExecute += new CanExecuteRoutedEventHandler(cb_CanExecute);
            commandBinding.Executed += new ExecutedRoutedEventHandler(cb_Execute);
            //把命令关联安置在外围控件上
            this.sp1.CommandBindings.Add(commandBinding);
        }
        //当命令到达目标之后，此方法被调用
        private void cb_Execute(object sender, ExecutedRoutedEventArgs e)
        {
            txtA.Clear();
            //避免事件继续向上传递而降低程序性能
            e.Handled = true;
        }
        //当探测命令是否可执行的时候该方法会被调用
        private void cb_CanExecute(object sender,CanExecuteRoutedEventArgs e)
        {
            if (string.IsNullOrEmpty(txtA.Text))
            {
                e.CanExecute = false;
            }
            else
            {
                e.CanExecute = true;
            }
            //避免事件继续向上传递而降低程序性能
            e.Handled = true;
        }

   <StackPanel Background="LightBlue" x:Name="sp1">
        <Button Content="Send Command" x:Name="btn1" Margin="5"></Button>
        <TextBox x:Name="txtA" Margin="5,0" Height="200"></TextBox>
    </StackPanel>

2.2 默认命令库

• ApplicationCommands
• ComponentCommands
• NavigationCommands
• MediaCommands
• EditingCommands

   <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="24" />
            <RowDefinition Height="4" />
            <RowDefinition Height="24" />
            <RowDefinition Height="4" />
            <RowDefinition Height="24" />
            <RowDefinition Height="4" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <!--命令和命令参数-->
        <TextBlock  HorizontalAlignment="Left" Name="textBlock1" Text="Name:" VerticalAlignment="Center" Grid.Row="0"/>
        <TextBox x:Name="txtName" Margin="60,0,0,0" Grid.Row="0"></TextBox>
        <Button Content="New Teacher" Grid.Row="2" Command="New" CommandParameter="Teacher"></Button>
        <Button Content="New Student" Grid.Row="4" Command="New" CommandParameter="Student"></Button>
        <ListBox Grid.Row="6" x:Name="lbInfos">
            
        </ListBox>
       
    </Grid>
    <!--为窗体添加CommandBinding-->
    <Window.CommandBindings>
        <CommandBinding Command="New" CanExecute="CommandBinding_CanExecute" Executed="CommandBinding_Executed">
            
        </CommandBinding>
    </Window.CommandBindings>

   private void CommandBinding_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            if (string.IsNullOrEmpty(txtName.Text))
            {
                e.CanExecute = false;
            }
            else
            {
                e.CanExecute = true;
            }
            //路由终止，提高系统性能
            e.Handled = true;
        }

        private void CommandBinding_Executed(object sender, ExecutedRoutedEventArgs e)
        {
            if (e.Parameter.ToString() == "Student")
            {
                this.lbInfos.Items.Add(string.Format("New Student:{0} 好好学习，天天向上。",txtName.Text));
            }
            else if(e.Parameter.ToString()=="Teacher")
            {
                this.lbInfos.Items.Add(string.Format("New Teacher:{0} 学而不厌，诲人不倦。", txtName.Text));
            }
            //路由终止，提高系统性能
            e.Handled = true;
        }