在Silverlight中使用HierarchicalDataTemplate为TreeView实现递归树状结构

这是项目中一个页面上的一个功能。我们需要在界面上通过一个TreeView控件显示一个递归的树状结构，也就是说会很多层嵌套的节点，而且层数是不确定的。

这个功能，可以通过HierarchicalDataTemplate来很方便地实现

1. 业务实体

作为举例，我定义了一个大家都很熟悉的Folder类型，即文件夹。我们都知道，文件夹又可以包含子文件夹，而且可以多层嵌套。所以，这是一个递归的结构体。

public class Folder
{
public string Name { get; set; }
public ObservableCollection<Folder> Folders { get; set; }
}

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

2. 准备数据

我用下面的代码，模拟一个数据读取操作。下面是硬编码出来的数据。实际情况下，可以读取数据库。

void MainPage_Loaded(object sender, RoutedEventArgs e)
{
var result = new[]{
new Folder(){Name="Test",Folders =new ObservableCollection<Folder>(
new[]{
new Folder(){Name="Test4"},
new Folder(){Name="Test3"},
new Folder(){Name="Test4",Folders=new ObservableCollection<Folder>(
new []{new Folder(){Name ="Test5"}})
}
})}};

tvFolders.ItemsSource = result;
}

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

3. 绑定控件

<UserControl x:Class="SilverlightTreeviewSample.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400" xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk">

<UserControl.Resources>
<sdk:HierarchicalDataTemplate x:Key="FolderItemTemplate" ItemsSource="{Binding Folders}">
<TextBlock Text="{Binding Name}"></TextBlock>
</sdk:HierarchicalDataTemplate>
<Style TargetType="sdk:TreeViewItem">
<Setter Property="IsExpanded" Value="True"></Setter>
</Style>

</UserControl.Resources>

<Grid x:Name="LayoutRoot" Background="White">
<sdk:TreeView  Name="tvFolders" ItemTemplate="{StaticResource FolderItemTemplate}">

</sdk:TreeView>
</Grid>
</UserControl>

请注意，我们这里用到一个特殊的DataTemplate：HierarchicalDataTemplate，并且将其设置为Treeview的ItemTemplate。
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

4. 查看效果