我們在用到ItemsControl時，有時會用到分組，如ListBox，ListView，DataGrid。WPF的ItemsControl可以實現分組，是依托於GroupStyle，以ListBox為例，他的分組效果圖為：
以下為前台：
1 <ListBox Name="lbMain">
2 <ListBox.ItemTemplate>
3 <DataTemplate>
4 <StackPanel Orientation="Horizontal">
5 <TextBlock Text="{Binding FileName}"
6 Width="150" />
7 <TextBlock Text="{Binding AuthorName}"
8 Width="100" />
9 <TextBlock Text="{Binding UpTime}"
10 Width="100" />
11 </StackPanel>
12 </DataTemplate>
13 </ListBox.ItemTemplate>
14 <ListBox.GroupStyle>
15 <GroupStyle>
16 <GroupStyle.ContainerStyle>
17 <Style TargetType="{x:Type GroupItem}">
18 <Setter Property="Template">
19 <Setter.Value>
20 <ControlTemplate TargetType="{x:Type GroupItem}">
21 <Expander IsExpanded="True"
22 ExpandDirection="Down">
23 <Expander.Header>
24 <StackPanel Orientation="Horizontal">
25 <TextBlock Text="{Binding Path=Name}"
26 VerticalAlignment="Center" />
27 <TextBlock Text="{Binding Path=ItemCount, StringFormat=數量:{0}}"
28 VerticalAlignment="Center"
29 Margin="5,0,0,0" />
30 <Button Content="Sale"
31 Margin="5,0,0,0" />
32 </StackPanel>
33 </Expander.Header>
34 <ItemsPresenter />
35 </Expander>
36 </ControlTemplate>
37 </Setter.Value>
38 </Setter>
39 </Style>
40 </GroupStyle.ContainerStyle>
41 </GroupStyle>
42 </ListBox.GroupStyle>
43 </ListBox>
從16行可以看出，GroupStyle定義的是控件內部樣式，所以有人嘗試在這里綁實體數據屬性的話肯定是失敗的，注意25行只能是Name，不管分組的屬性叫什么名，這都只能是Name，我寫了個Button在里面，如果想知道為什么只能是Name，寫個Click處理，把Button的DataContext打印出來就什么都知道了。如果想在這里做更多的處理，比如進行一些負責的運算，可以寫加轉換器。
這里只是弄了一個原始的Expander裝載分組控件，需要美化可以另寫樣式。
以下是后台：
1 public class ModelFile
2 {
3 public string FileName { get; set; }
4 public string AuthorName { get; set; }
5 public string UpTime { get; set; }
6 }
7
8 public partial class MainWindow : Window
9 {
10 public ObservableCollection<ModelFile> CollectionModelFile = new ObservableCollection<ModelFile>();
11
12 public MainWindow()
13 {
14 InitializeComponent();
15
16 CollectionModelFile.Add(new ModelFile() { FileName = "WPF進化史", AuthorName = "王鵬", UpTime = "2014-10-10" });
17 CollectionModelFile.Add(new ModelFile() { FileName = "WPF概論", AuthorName = "大飛", UpTime = "2014-10-10" });
18 CollectionModelFile.Add(new ModelFile() { FileName = "WPF之美", AuthorName = "小蟲", UpTime = "2014-10-11" });
19 CollectionModelFile.Add(new ModelFile() { FileName = "WPF之道", AuthorName = "青草", UpTime = "2014-11-11" });
20 CollectionModelFile.Add(new ModelFile() { FileName = "WPF之禪", AuthorName = "得瑟鬼", UpTime = "2014-11-11" });
21 CollectionModelFile.Add(new ModelFile() { FileName = "WPF入門", AuthorName = "今晚吃什么", UpTime = "2014-11-11" });
22 CollectionModelFile.Add(new ModelFile() { FileName = "WPF神技", AuthorName = "無間道王二", UpTime = "2014-12-12" });
23 CollectionModelFile.Add(new ModelFile() { FileName = "WPF不為人知之密", AuthorName = "星期八", UpTime = "2014-12-12" });
24 CollectionModelFile.Add(new ModelFile() { FileName = "WPF之革命", AuthorName = "兩把刀", UpTime = "2014-12-12" });
25
26 lbMain.ItemsSource = CollectionModelFile;
27
28 ICollectionView cv = CollectionViewSource.GetDefaultView(lbMain.ItemsSource);
29 cv.GroupDescriptions.Add(new PropertyGroupDescription("UpTime"));
30 }
31 }
重點是28、29行，有了這兩句，ListBox就能准確得分組顯示了，其他ItemsControl的分組類同。
至此一個簡單的ListBox分組顯示就完成了，Demo已放群里，需要的可以下載來看。