在充分尊重WPF MVVM的情况下，在每个节点中创建具有不同子对象的TreeView

放弃这些属性：Level1ViewModel.ChildLevel2FirstType和Level1ViewModel.ChildLevel2SecondType。

你需要为孩子们单独收集。此集合的项类型取决于继承层次结构，并且应该是最近的公共祖先(最坏的情况是object(，也就是说，如下所示：

public Level1ViewModel
{
    public ObservableCollection<object> ChildLevel2
    {
        // ...
    }
    // ...
}

带有这些更改的标记将如下所示：

    <!-- Level 1 -->
    <HierarchicalDataTemplate DataType="{x:Type local:Level1ViewModel}" ItemsSource="{Binding ChildLevel2}">
              <Label Content="{Binding ChildLevel1Name}"/>
    </HierarchicalDataTemplate>
    <!-- Level 1 -->
    <DataTemplate  DataType="{x:Type local:Level2FirstTypeViewModel}">
                <Label Content="{Binding SecondTypeName}"/>
    </DataTemplate>
    <DataTemplate  DataType="{x:Type local:Level2SecondTypeViewModel}">
               <Label Content="{Binding FirstTypeName}"/>
    </DataTemplate>

请注意，HierarchicalDataTemplate只能用于分层数据源。对于非分层的(如Level2FirstTypeViewModel和CCD_ 6(使用常规CCD_。

public class BaseTreeViewItem<TSource, TParent> : ViewModelBase
{
    // add static field to hold selected Item
    public static BaseTreeViewItem<TSource, TParent> SelectedChild { get; set; }
    private bool _isSelected;
    public bool IsSelected
    {
        get { return _isSelected; }
        set
        {
            if (_isSelected == value) return;
            if (SelectedChild != null)
            {
                SelectedChild.IsSelected = false;
                SelectedChild = null;
            }
            _isSelected = value;
            if (_isSelected)
                SelectedChild = this;
            // NotifyPropertyChanged
        }
    }
    public TParent Parent
    {
        get;
        private set;
    }
    public BaseTreeViewItem(string name, TSource myObj, TParent parent)
    {
        ChildName = name;
        DataSource = myObj;
        Parent = parent;
    }

    public string ChildName { get; set; }
    public TSource DataSource { get; set; }
    public override string ToString()
    {
        return ChildName;
    }
}
// Node
public class MyTreeViewItem<TChild, TSource, TParent> : BaseTreeViewItem<TSource, TParent>, IDeleteItem
    where TParent : IDeleteItem
    where TChild : class
{

    public ObservableCollection<TChild> Children { get; set; }
    public MyTreeViewItem(string name, TSource myObj, TParent parent)
        :base(name,myObj, parent)
    {
        Children = new ObservableCollection<TChild>();
    }
    protected virtual void InitChild()
    {
    }
    public void DeleteItem(object myTreeViewItem)
    {
        Children.Remove(myTreeViewItem as TChild);
    }
    public static void DeleteSelectedItem()
    {
        if (SelectedChild != null && SelectedChild.Parent != null)
        {
            SelectedChild.Parent.DeleteItem(SelectedChild);
        }
    }

}
public class Level0ViewModel : MyTreeViewItem<Level1ViewModel, XmlDocument, IDeleteItem>
{
    protected override sealed void InitChild()
    {
        base.InitChild();
        Children.Add(new Level1ViewModel("Child1", new Level1Src(), this));
        Children.Add(new Level1ViewModel("Child2", new Level1Src(), this));
    }
    public Level0ViewModel(string name, XmlDocument myObj) :
        base(name, myObj,null)
    {
        InitChild();
    }
}
public class Level1ViewModel : MyTreeViewItem<Level2TypeViewModel, Level1Src, Level0ViewModel>
{
    public Level1ViewModel(string name, Level1Src myObj, Level0ViewModel parent)
        : base(name, myObj, parent)
    {
        InitChild();
    }
    protected override sealed void InitChild()
    {
        base.InitChild();
        foreach (FirstType myFirstType in DataSource.FirstTypes)
        {
            Children.Add(new Level2TypeViewModel(myFirstType, this));
        }
        foreach (SecondType mySecondType in DataSource.SecondTypes)
        {
            Children.Add(new Level2TypeViewModel(mySecondType, this));
        }
    }
    // Use linq if tou want child by type
    public IEnumerable<Level2TypeViewModel> ChildType1 
    {
        get
        {
            return Children.Where(item => item.DataSource is FirstType);
        }
    }
    public IEnumerable<Level2TypeViewModel> ChildType2
    {
        get
        {
            return Children.Where(item => item.DataSource is SecondType);
        }
    }
}
public class LevelType
{
    public string Name;
}
public class FirstType : LevelType
{
}
public class SecondType : LevelType
{
}
public class Level2TypeViewModel : BaseTreeViewItem<LevelType, Level1ViewModel>
{
    public Level2TypeViewModel(LevelType sType, Level1ViewModel parent)
        : base(sType.Name, sType, parent)
    {
    }
}

我的数据源是

public Level0ViewModel TreeModel
    {
        get
        {
            return new Level0ViewModel("Root", new XmlDocument());
        }
    }

对于TreeView数据模板，请使用

<TreeView DataContext="{Binding ElementName=UI, Path=TreeModel}">
        <TreeView.Items>
            <TreeViewItem Header="{Binding ChildName}" ItemsSource="{Binding Path=Children}" >
                <TreeViewItem.ItemTemplate>
                    <HierarchicalDataTemplate ItemsSource="{Binding Children}">
                        <Label Content="{Binding ChildName}"></Label>
                    </HierarchicalDataTemplate>
                </TreeViewItem.ItemTemplate>
            </TreeViewItem>
        </TreeView.Items>
    </TreeView>

第一个treeviewItem用于显示根节点。如果你不想使用它您可以将数据源更改为

public MyTreeViewItem<Level0ViewModel,object> TreeModel
        {
            get
            {
                MyTreeViewItem<Level0ViewModel,object> src = new MyTreeViewItem<Level0ViewModel, object>("Root", null);
                src.Children.Add(new Level0ViewModel("toto", new XmlDocument()));
                return src;
            }
        }

和数据模板到

<TreeView DataContext="{Binding ElementName=UI, Path=TreeModel}" ItemsSource="{Binding Children}">
            <TreeViewItem.ItemTemplate>
                        <HierarchicalDataTemplate ItemsSource="{Binding Children}">
                            <Label Content="{Binding ChildName}"></Label>
                        </HierarchicalDataTemplate>
                    </TreeViewItem.ItemTemplate>
 </TreeView>

样本方式

public class TreeViewItemViewModel : ViewModelBase
{
    // add static field to hold selected Item
    public static TreeViewItemViewModel SelectedChild { get; set; }
    public TreeViewItemViewModel Parent{ get; private set;}
    public string ChildName { get; set; }
    public object DataSource { get; set; }
    private readonly ObservableCollection<TreeViewItemViewModel> _children;
    public ObservableCollection<TreeViewItemViewModel> Children
    {
        get
        {
            return _children;
        }
    }

    private bool _isSelected;
    public bool IsSelected
    {
        get { return _isSelected; }
        set
        {
            if (_isSelected == value) return;
            if (SelectedChild != null)
            {
                SelectedChild.IsSelected = false;
                SelectedChild = null;
            }
            _isSelected = value;
            if (_isSelected)
                SelectedChild = this;
            // NotifyPropertyChanged
        }
    }

    public TreeViewItemViewModel(string name, object myObj, TreeViewItemViewModel parent)
    {
        ChildName = name;
        DataSource = myObj;
        Parent = parent;
        _children = new ObservableCollection<TreeViewItemViewModel>();
    }
    public override string ToString()
    {
        return ChildName;
    }

    protected virtual void InitChild()
    {
    }
    public void DeleteItem(TreeViewItemViewModel myTreeViewItem)
    {
        Children.Remove(myTreeViewItem);
    }
    public static void DeleteSelectedItem()
    {
        if (SelectedChild != null && SelectedChild.Parent != null)
        {
            SelectedChild.Parent.DeleteItem(SelectedChild);
        }
    }
}

如果你的视图模型中有一个选定的项目，你可以使用这种方法

公共类TreeViewItemViewModel:ViewModelBase｛

    // add static field to hold selected Item
    public static TreeViewItemViewModel SelectedChild { get; set; }
    public TreeViewItemViewModel Parent{ get; private set;}
    public string ChildName { get; set; }
    public object DataSource { get; set; }
    private readonly ObservableCollection<TreeViewItemViewModel> _children;
    public ObservableCollection<TreeViewItemViewModel> Children
    {
        get
        {
            return _children;
        }
    }

    private bool _isSelected;
    public bool IsSelected
    {
        get { return _isSelected; }
        set
        {
            if (_isSelected == value) return;
            if (SelectedChild != null)
            {
                SelectedChild.IsSelected = false;
                SelectedChild = null;
            }
            _isSelected = value;
            if (_isSelected)
                SelectedChild = this;
            // NotifyPropertyChanged
        }
    }

    public TreeViewItemViewModel(string name, object myObj, TreeViewItemViewModel parent)
    {
        ChildName = name;
        DataSource = myObj;
        Parent = parent;
        _children = new ObservableCollection<TreeViewItemViewModel>();
    }
    public override string ToString()
    {
        return ChildName;
    }

    protected virtual void InitChild()
    {
    }
    public void DeleteItem(TreeViewItemViewModel myTreeViewItem)
    {
        Children.Remove(myTreeViewItem);
    }
    public static void DeleteSelectedItem()
    {
        if (SelectedChild != null && SelectedChild.Parent != null)
        {
            SelectedChild.Parent.DeleteItem(SelectedChild);
        }
    }
}