wpf mvvm MenuItem的Command事件

这是一个事件的辅助类，可以通过它实现MenuItem的Command事件

public class MyCommands : Freezable, ICommand, ICommandSource{public MyCommands() {}public static readonly DependencyProperty CommandParameterProperty =DependencyProperty.Register("CommandParameter",typeof(object),typeof(MyCommands),new PropertyMetadata((object)null));public object CommandParameter{get{return (object)GetValue(CommandParameterProperty);}set{SetValue(CommandParameterProperty, value);}}public static readonly DependencyProperty CommandTargetProperty =DependencyProperty.Register("CommandTarget",typeof(IInputElement),typeof(MyCommands),new PropertyMetadata((IInputElement)null));public IInputElement CommandTarget{get{return (IInputElement)GetValue(CommandTargetProperty);}set{SetValue(CommandTargetProperty, value);}}public static readonly DependencyProperty CommandProperty = DependencyProperty.Register("Command", typeof(ICommand), typeof(MyCommands), new PropertyMetadata(new PropertyChangedCallback(OnCommandChanged)));public ICommand Command{get { return (ICommand)GetValue(CommandProperty); }set { SetValue(CommandProperty, value); }}#region ICommand Memberspublic bool CanExecute(object parameter){if (Command != null)return Command.CanExecute(CommandParameter);return false;}public void Execute(object parameter){Command.Execute(CommandParameter);}public event EventHandler CanExecuteChanged;private static void OnCommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs e){MyCommands commandReference = d as MyCommands;ICommand oldCommand = e.OldValue as ICommand;ICommand newCommand = e.NewValue as ICommand;if (oldCommand != null){oldCommand.CanExecuteChanged -= commandReference.CanExecuteChanged;}if (newCommand != null){newCommand.CanExecuteChanged += commandReference.CanExecuteChanged;}}#endregion#region Freezableprotected override Freezable CreateInstanceCore(){throw new NotImplementedException();}#endregion}

在xaml中调用的方法

<UserControl.Resources><unititys:MyCommands x:Key="aaa" Command="{Binding Path=aaa}"/>
</UserControl.Resources><ContextMenu x:Key="RouterMenu1" DataContext="{Binding RelativeSource={RelativeSource Mode=Self}, Path=PlacementTarget.DataContext}"><MenuItem Header="调用aaa" Command="{StaticResource aaa}"></MenuItem></ContextMenu>