TreeView是一个树形结构的控件，能够表现出对象的层级关系，比如文件夹目录展示经常使用。

新建WPF应用程序，在界面上添加TreeView控件，最直接简单的用法是在TreeView下添加TreeViewItem节点，然后设置它的header，如果你的层级关系固定，内容比较少，可以直接采用这种方式。

<TreeView>
    <TreeViewItem Header="食物">
        <TreeViewItem Header="水果">
            <TreeViewItem Header="苹果"></TreeViewItem>
            <TreeViewItem Header="梨子"></TreeViewItem>
        </TreeViewItem>
        <TreeViewItem Header="蔬菜">
            <TreeViewItem Header="大白菜"></TreeViewItem>
            <TreeViewItem Header="空心菜"></TreeViewItem>
        </TreeViewItem>
    </TreeViewItem>
</TreeView>

我们还可以使用绑定的方式进行数据展示，在model中创建TreeNode类，写法如下，通常我们需要做属性变更通知，需要继承INotifyPropertyChanged，当然你可以写一个基类（比如：NotifyPropertyObject ）去继承这个接口，然后所有需要变更通知的类都继承于这个基类，就像下面的代码一样。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace Demo.Base
{
    public class NotifyPropertyObject : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler? PropertyChanged;
        public void RaisePropertyChanged([CallerMemberName] String propertyName = "")
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

using Demo.Base;
using System.Collections.ObjectModel;

namespace Demo.Model
{
    public class TreeNode : NotifyPropertyObject
    {
        private string m_Name;
        public string Name
        {
            get { return m_Name; }
            set
            {
                m_Name = value;
                this.RaisePropertyChanged(Name);
            }
        }
        private bool m_IsChecked = false;

        public bool IsChecked
        {
            get { return m_IsChecked; }
            set
            {
                m_IsChecked = value;
                this.RaisePropertyChanged("IsChecked");
            }
        }
        private ObservableCollection<TreeNode> m_Children = new ObservableCollection<TreeNode>();
        public ObservableCollection<TreeNode> Children
        {
            get
            {
                return m_Children;
            }
            set
            {
                m_Children = value;
                this.RaisePropertyChanged("Children");
            }
        }
    }
}

接下来，我们可以在ViewModel里头进行数据处理逻辑编写，并将界面的DataContext绑定到你的逻辑处理类中，这样我们就能够在界面上显示我们需要的数据了。

using Demo.Base;
using Demo.Model;
using System.Collections.ObjectModel;

public class TreeViewDemoViewModel: NotifyPropertyObject
{
    private ObservableCollection<TreeNode> m_TreeNodes = new ObservableCollection<TreeNode>();
    public ObservableCollection<TreeNode> TreeNodes
    {
        get
        {
            return m_TreeNodes;
        }
        set
        {
            m_TreeNodes = value;
            this.RaisePropertyChanged("TreeNodes");

        }
    }
    public TreeViewDemoViewModel() {

        TreeNode fruits = new TreeNode();
        fruits.Name = "水果";
        TreeNode apple = new TreeNode();
        apple.Name = "苹果";
        TreeNode Pear = new TreeNode();
        Pear.Name = "梨子";
        fruits.Children.Add(apple);
        fruits.Children.Add(Pear);

        TreeNode vegetables = new TreeNode();
        vegetables.Name = "蔬菜";
        TreeNode cabbage = new TreeNode();
        cabbage.Name = "卷心菜";
        TreeNode waterspinach = new TreeNode();
        waterspinach.Name = "空心菜";
        vegetables.Children.Add(cabbage);
        vegetables.Children.Add(waterspinach);

        TreeNode foods = new TreeNode();
        foods.Name = "食物";
        foods.Children.Add(fruits);
        foods.Children.Add(vegetables);

        TreeNodes.Add(foods);
    }
}

<TreeView ItemsSource="{Binding TreeNodes}">
    <TreeView.ItemTemplate>
        <HierarchicalDataTemplate ItemsSource="{Binding Children}">
            <Label Content="{Binding Name}"/>
        </HierarchicalDataTemplate>
    </TreeView.ItemTemplate>
</TreeView>

using Demo.View;
using System.Windows;

namespace TreeViewDemo
{
    /// <summary>
    /// Interaction logic for App.xaml
    /// </summary>
    public partial class App : Application
    {
        protected override void OnStartup(StartupEventArgs e)
        {
            TreeViewDemoView treeViewDemoView = new TreeViewDemoView();
            TreeViewDemoViewModel treeViewDemoViewModel = new TreeViewDemoViewModel();
            treeViewDemoView.DataContext = treeViewDemoViewModel;
            treeViewDemoView.Show();
        }
    }
}

效果预览

完整代码

https://gitee.com/rdonly/demo