PRISM MVVM Reference Implementation 有一个称为 SynchronizeSelectedItems 的行为，在 Prism4\MVVM RI\MVVM.Client\Views\MultipleSelectionView.xaml 中使用，它将选中的项目与名为 Selections 的 ViewModel 属性同步：
<ListBox Grid.Column="0" Grid.Row="1" IsTabStop="False" SelectionMode="Multiple"
ItemsSource="{Binding Question.Range}" Margin="5">
<ListBox.ItemContainerStyle>
<!-- Custom style to show the multi-selection list box as a collection of check boxes -->
<Style TargetType="ListBoxItem">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBoxItem">
<Grid Background="Transparent">
<CheckBox IsChecked="{Binding IsSelected, RelativeSource={RelativeSource TemplatedParent}, Mode=TwoWay}"
IsHitTestVisible="False" IsTabStop="True"
AutomationProperties.AutomationId="CheckBoxAutomationId">
<ContentPresenter/>
</CheckBox>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ListBox.ItemContainerStyle>
<i:Interaction.Behaviors>
<!-- Custom behavior that synchronizes the selected items with the view models collection -->
<Behaviors:SynchronizeSelectedItems Selections="{Binding Selections}"/>
</i:Interaction.Behaviors>
</ListBox>
转到http://compositewpf.codeplex.com/ 并全部获取或使用它：
//===================================================================================
// Microsoft patterns & practices
// Composite Application Guidance for Windows Presentation Foundation and Silverlight
//===================================================================================
// Copyright (c) Microsoft Corporation. All rights reserved.
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
// FITNESS FOR A PARTICULAR PURPOSE.
//===================================================================================
// The example companies, organizations, products, domain names,
// e-mail addresses, logos, people, places, and events depicted
// herein are fictitious. No association with any real company,
// organization, product, domain name, email address, logo, person,
// places, or events is intended or should be inferred.
//===================================================================================
using System;
using System.Collections;
using System.Collections.Specialized;
using System.Diagnostics.CodeAnalysis;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Interactivity;
namespace MVVM.Client.Infrastructure.Behaviors
{
/// <summary>
/// Custom behavior that synchronizes the list in <see cref="ListBox.SelectedItems"/> with a collection.
/// </summary>
/// <remarks>
/// This behavior uses a weak event handler to listen for changes on the synchronized collection.
/// </remarks>
public class SynchronizeSelectedItems : Behavior<ListBox>
{
public static readonly DependencyProperty SelectionsProperty =
DependencyProperty.Register(
"Selections",
typeof(IList),
typeof(SynchronizeSelectedItems),
new PropertyMetadata(null, OnSelectionsPropertyChanged));
private bool updating;
private WeakEventHandler<SynchronizeSelectedItems, object, NotifyCollectionChangedEventArgs> currentWeakHandler;
[SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly",
Justification = "Dependency property")]
public IList Selections
{
get { return (IList)this.GetValue(SelectionsProperty); }
set { this.SetValue(SelectionsProperty, value); }
}
protected override void OnAttached()
{
base.OnAttached();
this.AssociatedObject.SelectionChanged += this.OnSelectedItemsChanged;
this.UpdateSelectedItems();
}
protected override void OnDetaching()
{
this.AssociatedObject.SelectionChanged += this.OnSelectedItemsChanged;
base.OnDetaching();
}
private static void OnSelectionsPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var behavior = d as SynchronizeSelectedItems;
if (behavior != null)
{
if (behavior.currentWeakHandler != null)
{
behavior.currentWeakHandler.Detach();
behavior.currentWeakHandler = null;
}
if (e.NewValue != null)
{
var notifyCollectionChanged = e.NewValue as INotifyCollectionChanged;
if (notifyCollectionChanged != null)
{
behavior.currentWeakHandler =
new WeakEventHandler<SynchronizeSelectedItems, object, NotifyCollectionChangedEventArgs>(
behavior,
(instance, sender, args) => instance.OnSelectionsCollectionChanged(sender, args),
(listener) => notifyCollectionChanged.CollectionChanged -= listener.OnEvent);
notifyCollectionChanged.CollectionChanged += behavior.currentWeakHandler.OnEvent;
}
behavior.UpdateSelectedItems();
}
}
}
private void OnSelectedItemsChanged(object sender, SelectionChangedEventArgs e)
{
this.UpdateSelections(e);
}
private void UpdateSelections(SelectionChangedEventArgs e)
{
this.ExecuteIfNotUpdating(
() =>
{
if (this.Selections != null)
{
foreach (var item in e.AddedItems)
{
this.Selections.Add(item);
}
foreach (var item in e.RemovedItems)
{
this.Selections.Remove(item);
}
}
});
}
private void OnSelectionsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
this.UpdateSelectedItems();
}
private void UpdateSelectedItems()
{
this.ExecuteIfNotUpdating(
() =>
{
if (this.AssociatedObject != null)
{
this.AssociatedObject.SelectedItems.Clear();
foreach (var item in this.Selections ?? new object[0])
{
this.AssociatedObject.SelectedItems.Add(item);
}
}
});
}
private void ExecuteIfNotUpdating(Action execute)
{
if (!this.updating)
{
try
{
this.updating = true;
execute();
}
finally
{
this.updating = false;
}
}
}
}
}