WPF MVVM实现TreeView

    /// <summary>
    /// </summary>
    public class NotifyPropertyBase : INotifyPropertyChanged
        #region INotifyPropertyChanged
        public void OnPropertyChanged(string propertyName)
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        public event PropertyChangedEventHandler PropertyChanged;
        #endregion
    }

  /// <summary>
    /// 扩展方法
    /// 避免硬编码问题
    /// </summary>
    public static class NotifyPropertyBaseEx
        public static void SetProperty<T, U>(this T tvm, Expression<Func<T, U>> expre) where T : NotifyPropertyBase, new()
            string _pro = CommonFun.GetPropertyName(expre);
            tvm.OnPropertyChanged(_pro);
    #endregion
    public class CommonFun
        /// <summary>
        /// 返回属性名
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <typeparam name="U"></typeparam>
        /// <param name="expr"></param>
        /// <returns></returns>
        public static string GetPropertyName<T, U>(Expression<Func<T, U>> expr)
            string _propertyName = "";
            if (expr.Body is MemberExpression)
                _propertyName = (expr.Body as MemberExpression).Member.Name;
            else if (expr.Body is UnaryExpression)
                _propertyName = ((expr.Body as UnaryExpression).Operand as MemberExpression).Member.Name;
            return _propertyName;
    }

 /// <summary>
    /// 因为用到泛型了不能写成abstract 类
    /// </summary>
    public  class MyTree : NotifyPropertyBase
        #region 父
        public MyTree Parent
        #endregion
        #region 子
        public List<MyTree> Children
        #endregion
        #region 节点的名字
        public string Name
        #endregion
        #region Constructors
        public MyTree(string name)
            this.Name=name;
            this.Children=new List<MyTree>();
        public MyTree() { }
        public 
        #endregion
        #region CheckBox是否选中
        bool? _isChecked;
        public bool? IsChecked
                return _isChecked;
                SetIsChecked(value, true, true);
        private void SetIsChecked(bool? value, bool checkedChildren, bool checkedParent)
            if (_isChecked == value) return;
            _isChecked = value;
            //选中和取消子类
            if (checkedChildren && value.HasValue && Children != null)
                Children.ForEach(ch => ch.SetIsChecked(value, true, false));
            //选中和取消父类
            if (checkedParent && this.Parent != null)
                this.Parent.CheckParentCheckState();
            //通知更改
            this.SetProperty(x => x.IsChecked);
        /// <summary>
        /// 检查父类是否选 中
        /// 如果父类的子类中有一个和第一个子类的状态不一样父类ischecked为null
        /// </summary>
        private void CheckParentCheckState()
            bool? _currentState = this.IsChecked;
            bool? _firstState = null;
            for (int i = 0; i < this.Children.Count(); i++)
                bool? childrenState = this.Children[i].IsChecked;
                if (i == 0)
                    _firstState = childrenState;
                else if (_firstState != childrenState)
                    _firstState = null;
            if (_firstState != null) _currentState = _firstState;
            SetIsChecked(_firstState, false, true);
        #endregion
        #region 选中的行 IsSelected
        bool _isSelected;
        public bool IsSelected
                return _isSelected;
                _isSelected = value;
                this.SetProperty(x => x.IsChecked);
                if (_isSelected)
                    SelectedTreeItem = this;
                    MessageBox.Show("选中的是" + SelectedTreeItem.Name);
                    SelectedTreeItem = null;
        #endregion
        #region 选中的数据
        public MyTree SelectedTreeItem
        #endregion
        #region 创建树
        public void CreateTreeWithChildre( MyTree children,bool? isChecked)
            this.Children.Add(children);
            children.Parent = this;
            children.IsChecked = isChecked;
        #endregion
    }

 public class TreeViewModel:NotifyPropertyBase
        public List<MyTree> MyTrees
        public TreeViewModel()
            MyTrees = new List<MyTree>();
            MyTrees.Add(MyCreateTree());
        /// <summary>
        /// 创建树
        /// </summary>
        /// <returns></returns>
        public MyTree MyCreateTree()
            MyTree _myT = new MyTree("中国");
            #region 北京
            MyTree _myBJ = new MyTree("北京");
            _myT.CreateTreeWithChildre(_myBJ, false);
            MyTree _HD = new MyTree("海淀区");
            MyTree _CY = new MyTree("朝阳区");
            MyTree _FT = new MyTree("丰台区");
            MyTree _DC = new MyTree("东城区");
            _myBJ.CreateTreeWithChildre(_HD, false);
            _HD.CreateTreeWithChildre(new MyTree("某某1"), false);
            _HD.CreateTreeWithChildre(new MyTree("某某2"), true);
            _myBJ.CreateTreeWithChildre(_CY, false);
            _myBJ.CreateTreeWithChildre(_FT, false);
            _myBJ.CreateTreeWithChildre(_DC, false);
            #endregion
            #region 河北
            MyTree _myHB = new MyTree("河北");
            _myT.CreateTreeWithChildre(_myHB, false);
            MyTree _mySJZ = new MyTree("石家庄");
            MyTree _mySD = new MyTree("山东");
            MyTree _myTS = new MyTree("唐山");
            _myHB.CreateTreeWithChildre(_mySJZ, true);
            _myHB.CreateTreeWithChildre(_mySD, false);
            _myHB.CreateTreeWithChildre(_myTS, false);
            #endregion
            return _myT;
    }

<Window x:Class="MyWpfCheckTreeDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:VM="clr-namespace:MyWpfCheckTreeDemo.AppViewModel"
        Title="MainWindow" Height="350" Width="525" Loaded="LoadedEvent">
    <Window.Resources>
        <HierarchicalDataTemplate x:Key="MyTreeItemTemplate"  DataType="{x:Type VM:MyTree}" ItemsSource="{Binding Path=Children,Mode=OneWay}">
            <StackPanel x:Name="My_SP"  Orientation="Horizontal" Margin="2">
                <CheckBox  IsChecked="{Binding Path=IsChecked}" >
                </CheckBox>
                <ContentPresenter  Content="{Binding Path=Name,Mode=OneTime}" Margin="2,0"/>
            </StackPanel>
        </HierarchicalDataTemplate>
        <Style x:Key="TreeViewItemStyle" TargetType="{x:Type TreeViewItem}">
            <Setter Property="IsExpanded" Value="True" />
            <Setter Property="IsSelected" Value="{Binding Path=IsSelected,Mode=TwoWay}"/>
        </Style>
    </Window.Resources>
        <DockPanel>
            <TreeView  x:Name="tv" ItemsSource="{Binding MyTrees}"
                      ItemContainerStyle="{StaticResource TreeViewItemStyle}"
                      ItemTemplate="{StaticResource MyTreeItemTemplate}"
                      ></TreeView>
        </DockPanel>
    </Grid>
</Window>