using System.Collections.Generic;
using System.IO;

namespace WpfApplication1
{

    class BindDirectory
    {
        public BindDirectory(string directoryPath)
        {
            //正规化目录路径,确保Path以'\\'结尾
            directoryPath = directoryPath.TrimEnd('\\');
            Path = directoryPath + '\\';

            //计算出目录名称(不包含路径)
            int indexLastSlash = directoryPath.LastIndexOf('\\');
            if (indexLastSlash >= 0)
            {
                Name = directoryPath.Substring(indexLastSlash + 1);
            }
            else
            {
                Name = directoryPath;
            }
        }

        public string Name
        {
            get;
            private set;
        }

        public string Path
        {
            get;
            private set;
        }

        public IEnumerable<BindDirectory> Directories
        {
            get
            {
                //延迟加载
                if (directories == null)
                {
                    directories = new List<BindDirectory>();
                    foreach (string d in Directory.GetDirectories(Path))
                    {
                        directories.Add(new BindDirectory(d));
                    }
                }
                return directories;
            }

        }
        List<BindDirectory> directories;
    }
}

using System.Collections.Generic;
using System.IO;

namespace WpfApplication1
{
    class BindDirectoryList : List<BindDirectory>
    {
        public BindDirectoryList()
        {
            foreach (var drive in DriveInfo.GetDrives())
            {
                Add(new BindDirectory(drive.RootDirectory.FullName));
            }
        }
    }
}

<!--xml:sample这一行用来引入我们自己代码的命名空间-->
<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:sample="clr-namespace:WpfApplication1"
    Title="Window1" Height="300" Width="300">
    <Window.Resources>
        <!--引入我们自己的数据提供对象-->
        <ObjectDataProvider x:Key="drives" ObjectType="{x:Type sample:BindDirectoryList}" />
        <!--设置如何显示数据,以及如何获取下一级数据的列表-->
        <HierarchicalDataTemplate x:Key="itemTemplate" DataType="{x:Type sample:BindDirectory}" ItemsSource="{Binding Directories}">
            <TextBlock Text="{Binding Name}" />
        </HierarchicalDataTemplate>
    </Window.Resources>
    <TreeView ItemsSource="{Binding Source={StaticResource drives}}"
             ItemTemplate="{StaticResource itemTemplate}" >
    </TreeView>
</Window>