WPF中Cammand命令

Cammand命令

命令
实现了ICammand接口，常用的是继承RoutedCommand子类
命令源
实现了ICommandSource接口
命令目标
实现了IInpurElement接口,常常是直接对UI控件进行扩展

命令多使用单件模式………Singletone Pattern

1.创建命令类
2.声明命令实例
3.指定命令源
4.指定命令目标
5.设置命令关联

CommandManager:
PreviewCanExecute , PreviewExecute
CanExecute,Executed

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CommandSource有Command,
CommandSource不断的向CommandTarget发送CanExecute和Executed,
CommandTarget向CommandBinding发送路由事件，
CommandBinding捕捉并处理事件，向Command反馈。

//定义命令private RoutedCommand clearCmd = new RoutedCommand("Clear",typeof(Window1));...private void InitializeCommand(){    //指定命令源---------给控件添加命令    this.button1.Command = this.clearCmd;    this.clearCmd = InputGesture.Add(new KeyGesture(Key.C,Modifierkeys.Alt));    //指定命令目标    this.button1.CommandTarget = this.textBoxA;    创建CommandBinding    CommandBinding cb = new CommandBinding();    cb.Command = this.clearCmd;    cb.CanExecute += new CanExecuteRoutedEventHandler(cb_CanExecute);    cb.Executed += new ExecutedRoutedEventHandler(cb_Executed);    //把CommandBinding设置在外围控件上    this.stackPanel.CommandBindings.Add(cb);}    void cb_CanExecute(object sender , CanExecuteRoutedEventArgs e){        if(string IsNullOrEmpty(this.textBoxA.Text)){            e.CanExecute = false;        }else{ e.CanExecute = true}        e.Handled = true;    }    void cb_Executed(object sender , CanExecuteRoutedEventArgs e){        this.textBoxA.Clear();        e.Handled = true;    }

命令参数 CommandParamter—命令携带的信息

<Button ... Command = "New" CommandParamter = "Teacher"/><Button ... Command = "New" CommandParamter = "Student"/>...<Window.CommandBinds>    <CommandBinding Command = "New" CommandParamter = "Teacher" CanExecute = "New_CanExecute" Executed = "New_Executed"/></Window.CommandBinds>...private void New_Executed(object sender , CanExecuteRoutedEventArgs e){    if(e.Parameter.ToString() == "Teacher"){ ... }    if(e.Parameter.ToString() == "Student"){ ... }}

命令与Binding结合…使命令的赋值更加灵活

<Button x:Name = "dynamicCmdBtn" Command = "{Binding Path=ppp,Source=sss}" Content = "Command" }

可以根据特定条件改变命令

ICommand接口:
1.CanExecute方法
2.Execute方法
3.CanExecuteChanged事件

ICommandSource接口
1.Command属性
2.CommandParamter属性
3.CommandTarget属性

RoutedCommand类…实现了Icommand接口的类
并未向CanExecute方法和Execute方法添加任何逻辑
RoutedCommand与业务逻辑无关
业务逻辑要依靠外围组件的CommandBinding来实现
尽量把逻辑卸载Execute方法内

自定义命令
1.声明定义自己的RoutedCommand实例
2.实现ICommand接口,实现自己的业务逻辑，实现ICommandSource接口

例:

//定义接口public interface IView{    bool IsChanged {get;set;}    void SetBinding();    void Refresh();    void Clear();    void Save();}//实现ICommand接口，创建一个作用于IView的命令public class ClearCommand : ICommand{    public event EventHandler CanExecuteChanged;    public bool CanExecute(object Parameter){...};    public void Execute(object Parameter){        IView view = Paramter as IView;        if( view != null ){ view.Clear(); }    }}//实现ICommandSource接口 public class MyCommandSource : UserControl,ICommandSource{     //继承自 ICommandSource的三个属性     public ICommand Command{get;set;}     public object CommandParameter{get;set;}     public IInputElement CommandTarget{get;set;}    //实现点击事件    protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e){        base.OnMouseLeftButtonDown(e);        if(e.CommandTarget != null){            this.Command.Execute(this.CommandTarget);        }    } }

实现IView的子类时先编辑XAML,再实现IView接口

InitializeComponent();...ClearCommand clearCmd = new ClearCommand();this.ctrlClear.Command = clearCmd;this.ctrlClear.CommandTarget = this.mineView//minewView实现IView接口