必须将所有模板定义为隐式HierarchicalDataTemplate。这意味着您 * 必须 * 设置HierarchicalDataTemplate.DataType属性，并将没有显式键的模板添加到TreeView范围内的ResourceDictionary（例如TreeView.Resources或 App.xaml）。
现在，当您为每个数据模型类型定义一个隐式HierarchicalDataTemplate（或DataTemplate，如果节点不能有或不允许有子节点）时，WPF将自动为树中的当前数据模型类型加载匹配模板。
或者定义一个DataTemplateSelector来显式地选择要为当前数据模型加载的模板。
下面的示例显示如何隐式定义数据树视觉外观，以允许具有动态树级别（深度和宽度/广度）和树组成的完全动态树结构。该树随机包含橙子、黄色和蓝色节点，这些节点被渲染为圆形、矩形和直线。

MainWindow.xaml.cs

private void OnLoaded(object sender, RoutedEventArgs e)
{
  var orange1 = new OrangeDataModel("Orange 1 (Root)");

  var yellow1 = new YellowDataModel("Yellow 1");
  orange1.Children.Add(yellow1);

  var blue1 = new BlueDataModel("Blue 1");
  orange1.Children.Add(blue1);

  var orange2 = new OrangeDataModel("Orange 2");
  var orange3 = new OrangeDataModel("Orange 3");
  blue1.Children.Add(orange2);
  blue1.Children.Add(orange3);

  var yellow2 = new YellowDataModel("Yellow 2");
  blue1.Children.Add(yellow2);

  var blue2 = new BlueDataModel("Blue 2");
  var blue3 = new BlueDataModel("Blue 3");
  yellow2.Children.Add(blue1);
  yellow2.Children.Add(blue3);
      
  var orange4 = new OrangeDataModel("Orange 4");
  yellow1.Children.Add(orange4);

  var root = new ObservableCollection<object> { orange1 };
  this.TreeView.ItemsSource = root;
}

MainWindow.xaml

<TreeView x:Name="TreeView">
  <TreeView.Resources>
    <HierarchicalDataTemplate DataType="{x:Type local:OrangeDataModel}"
                              ItemsSource="{Binding Yellows}">
      <Grid>
        <Ellipse Height="50"
                  Width="50"
                  Fill="DarkOrange" />
        <TextBlock Text="{Binding TextValue}" />
      </Grid>
    </HierarchicalDataTemplate>
    <HierarchicalDataTemplate DataType="{x:Type local:YellowDataModel}"
                              ItemsSource="{Binding Blues}">
      <Grid>
        <Rectangle Height="50"
                    Width="50"
                    Fill="Yellow" />
        <TextBlock Text="{Binding TextValue}" />
      </Grid>
    </HierarchicalDataTemplate>
    <HierarchicalDataTemplate DataType="{x:Type local:BlueDataModel}"
                              ItemsSource="{Binding Oranges}">
      <Grid>
        <Line X2="50"
              Stroke="Blue" />
        <TextBlock Text="{Binding TextValue}" />
      </Grid>
    </HierarchicalDataTemplate>
  </TreeView.Resources>
</TreeView>

OrangeDataModel.cs

public class OrangeDataModel : INotifyPropertyChanged
{
  public OrangeDataModel(string textValue)
  {
    this.TextValue = textValue;
    this.Yellows = new ObservableCollection<object>();
  }

  public string TextValue { get; set; }
  public ObservableCollection<object> Children { get; }
  public event PropertyChangedEventHandler? PropertyChanged;
}

YellowDataModel.cs

public class YellowDataModel : INotifyPropertyChanged
{
  public YellowDataModel(string textValue)
  {
    this.TextValue = textValue;
    this.Blues = new ObservableCollection<object>();
  }

  public string TextValue { get; set; }
  public ObservableCollection<object> Children{ get; }
  public event PropertyChangedEventHandler? PropertyChanged;
}

BlueDataModel.cs

public class BlueDataModel : INotifyPropertyChanged
{
  public BlueDataModel(string textValue)
  {
    this.TextValue = textValue;
    this.Oranges = new ObservableCollection<object>();
  }

  public string TextValue { get; set; }
  public ObservableCollection<object> Children{ get; }
  public event PropertyChangedEventHandler? PropertyChanged;
}