MVVM通过Command 绑定 关闭窗体

View:

<Button Name="btnExit" Command="{Binding ExitCommand}" CommandParameter="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}" IsDefault="True" Style="{StaticResource ButtonBackgroundChanged}"  Foreground="White"  Margin="10,0,20,0">关 闭</Button>

<Controls:MetroWindow x:Class="ETRIMP_CustomsDeclarationWPF.WPF_CustomsDeclarationShow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" ShowSystemMenuOnRightClick="False"
    xmlns:viewModel="clr-namespace:ETRIMP_CustomsDeclarationWPF.ViewModel">
    <Window.DataContext>
        <viewModel:CustomsDeclarationShowViewModel/>
    </Window.DataContext>

这里注意页面设置DataContext,指定ViewModel路径:

xmlns:viewModel="clr-namespace:ETRIMP_CustomsDeclarationWPF.ViewModel"

ViewModel:

public ICommand ExitCommand
{
    get { return new RelayCommand<Window>(wd =>
    {
        if (wd != null)
        {
            wd.Close();
        }
    });}
}

 

RelayCommand: 

/// <summary>
    /// A command whose sole purpose is to relay its functionality to other objects by invoking delegates. The default return value for the CanExecute method is 'true'.
    /// </summary>
    public class RelayCommand<T> : ICommand
    {

        #region Declarations

        readonly Predicate<T> _canExecute;
        readonly Action<T> _execute;

        #endregion

        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="RelayCommand&lt;T&gt;"/> class and the command can always be executed.
        /// </summary>
        /// <param name="execute">The execution logic.</param>
        public RelayCommand(Action<T> execute)
            : this(execute, null)
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="RelayCommand&lt;T&gt;"/> class.
        /// </summary>
        /// <param name="execute">The execution logic.</param>
        /// <param name="canExecute">The execution status logic.</param>
        public RelayCommand(Action<T> execute, Predicate<T> canExecute)
        {

            if (execute == null)
                throw new ArgumentNullException("execute");
            _execute = execute;
            _canExecute = canExecute;
        }

        #endregion

        #region ICommand Members

        public event EventHandler CanExecuteChanged
        {
            add
            {

                if (_canExecute != null)
                    CommandManager.RequerySuggested += value;
            }
            remove
            {

                if (_canExecute != null)
                    CommandManager.RequerySuggested -= value;
            }
        }

        [DebuggerStepThrough]
        public Boolean CanExecute(Object parameter)
        {
            return _canExecute == null ? true : _canExecute((T)parameter);
        }

        public void Execute(Object parameter)
        {
            _execute((T)parameter);
        }

        #endregion
    }

    /// <summary>
    /// A command whose sole purpose is to relay its functionality to other objects by invoking delegates. The default return value for the CanExecute method is 'true'.
    /// </summary>
    public class RelayCommand : ICommand
    {

        #region Declarations

        readonly Func<Boolean> _canExecute;
        readonly Action _execute;

        #endregion

        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="RelayCommand&lt;T&gt;"/> class and the command can always be executed.
        /// </summary>
        /// <param name="execute">The execution logic.</param>
        public RelayCommand(Action execute)
            : this(execute, null)
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="RelayCommand&lt;T&gt;"/> class.
        /// </summary>
        /// <param name="execute">The execution logic.</param>
        /// <param name="canExecute">The execution status logic.</param>
        public RelayCommand(Action execute, Func<Boolean> canExecute)
        {

            if (execute == null)
                throw new ArgumentNullException("execute");
            _execute = execute;
            _canExecute = canExecute;
        }

        #endregion

        #region ICommand Members

        public event EventHandler CanExecuteChanged
        {
            add
            {

                if (_canExecute != null)
                    CommandManager.RequerySuggested += value;
            }
            remove
            {

                if (_canExecute != null)
                    CommandManager.RequerySuggested -= value;
            }
        }

        [DebuggerStepThrough]
        public Boolean CanExecute(Object parameter)
        {
            return _canExecute == null ? true : _canExecute();
        }

        public void Execute(Object parameter)
        {
            _execute();
        }

        #endregion
    }

 

我这种写法需要利用上面这个ICommand实现类.