WPF TreeView递归异步绑定

WPF的TreeView不像WinForms的TreeView那样，通过TreeNode实现树型节点。WPF的TreeView实现起来，我感觉有点像VM(View-Model)模式，就像WinForms中的DataGrid，控件负责显示，数据在DataTable中。那么我们在实现TreeView时，也需要用这样的思路，数据在Model中，控件是View负责显示。

我需要实现的最终目标是：
1.节点是异步加载的（解决效率问题）
2.节点是无限级别的（递归的，这样可复用与目录结构、组织架构等数据类型）
3.节点是可以多选的（用CheckBox选择）
4.XAML方式绑定（减少UI上Code量）
5.方便得获取选中项信息

先看效果图：


1）数据库设计与准备
为了演示方便，采用了ACCESS数据库，添加一个Department表
表字段：

数据内容：

2）创建WPF项目

3）数据访问类
为了图方便，我采用了Linq to DataSet

usingSystem;
 usingSystem.Collections.Generic;
 usingSystem.Linq;
 usingSystem.Text;
 usingDepartmentTreeView.DB;
 usingSystem.Collections;
 usingDepartmentTreeView.DB.SampleDataSetTableAdapters;

 namespaceDepartmentTreeView{
 publicclassDepartmentHelper{

 staticSampleDataSetds=newSampleDataSet();
 staticDepartmentTableAdapterda=newDepartmentTableAdapter();

 staticDepartmentHelper(){
da.Fill(ds.Department);
}

 publicstaticobjectGetDepartment(intdid){
vardepart=ds.Department.Where(c=>c.DID==did).SingleOrDefault();
 returndepart;
}

 publicstaticIEnumerableGetSubDepartments(intpid){
varlist=ds.Department.Where(c=>c.PID==pid).ToList();
 returnlist;
}
}
}

4）创建TreeView 的Model类DepartmentViewModel

usingSystem;
 usingSystem.Collections.Generic;
 usingSystem.Linq;
 usingSystem.Text;
 usingSystem.ComponentModel;
 usingSystem.Collections.ObjectModel;

 namespaceDepartmentTreeView{
 publicclassDepartmentViewModel:INotifyPropertyChanged{
 //临时子节点用，当Expanded时移除此节点，添加子节点
 staticreadonlyDepartmentViewModel_temp=newDepartmentViewModel(null);
 //选中的子节点
 privatestaticObservableCollection_checkedItems=newObservableCollection();
 //根节点
 staticDepartmentViewModel_rootItem;

#regionfields&properties
 privatebool?_isChecked;
 publicbool?IsChecked{
 get{return_isChecked;}
 set{
 SetCheckState(value,true,true);

}
}
 privatevoidSetCheckState(bool?value,boolupdateChildren,boolupdateParent){
 if(_isChecked!=value){
_isChecked=value;

 //通知选中项的集合
 if(_isChecked==true){
 _checkedItems.Add(this);
 PropertyChanged(this,newPropertyChangedEventArgs("CheckedItems"));
 }elseif(_isChecked==false){
 _checkedItems.Remove(this);
 PropertyChanged(this,newPropertyChangedEventArgs("CheckedItems"));
}

 PropertyChanged(this,newPropertyChangedEventArgs("IsChecked"));

 if(updateChildren){
 if(HasChildren()){
 Children.ForEach(c=>c.SetCheckState(value,true,false));
}
}
 if(updateParent&&_parent!=null){
_parent.VerifyState();
}
}
}
 privatevoidVerifyState(){
 bool?state=null;
 for(inti=0;i<this.Children.Count;++i){
 bool?currentState=this.Children[i].IsChecked;
 if(i==0){
state=currentState;
 }elseif(state!=currentState){
 state=null;
 break;
}
}
 this.SetCheckState(state,false,true);
}

 privatebool_isExpanded;
 publicboolIsExpanded{
 get{return_isExpanded;}
 set{
 if(value!=_isExpanded){
_isExpanded=value;
 PropertyChanged(this,newPropertyChangedEventArgs("IsExpanded"));
}
 if(!HasChildren()){
Children.Remove(_temp);
LoadChildren();
}
}
}

 privateobject_current;
 publicobjectCurrent{
 get{return_current;}
 set{_current=value;}
}
 publicstringDisplayText{
 get{return((DepartmentTreeView.DB.SampleDataSet.DepartmentRow)Current)["DName"].ToString();}
}

 privateDepartmentViewModel_parent;
 publicDepartmentViewModelParent{
 get{return_parent;}
 set{_parent=value;}
}

 privateList_children;
 publicListChildren{
 get{return_children;}
 privateset{_children=value;}
 }
#endregion

 publicstaticListCreate(){
varlist=DepartmentHelper.GetSubDepartments(0);
 DepartmentViewModelroot=newDepartmentViewModel(null);
_rootItem=root;
root.Children.Clear();
 foreach(variteminlist){
 root.Children.Add(newDepartmentViewModel(item));
}
 returnroot.Children;
}
 privateDepartmentViewModel(objectcurrentObject){
Current=currentObject;
 _isChecked=false;
 Children=newList();
Children.Add(_temp);
}

 ///
 ///初始化，用于设置父节点
 ///
 privatevoidInit(){
 if(!HasChildren())return;
 foreach(DepartmentViewModelchildinChildren){
 child.Parent=this;
child.Init();
}
 PropertyChanged(this,newPropertyChangedEventArgs("Children"));
}

 ///
 ///加载子节点
 ///
 privatevoidLoadChildren(){
 if(Current!=null){
 intpid=Convert.ToInt32(((DepartmentTreeView.DB.SampleDataSet.DepartmentRow)Current)["DID"]);
varlist=DepartmentHelper.GetSubDepartments(pid);
 foreach(variteminlist){
 DepartmentViewModelmodel=newDepartmentViewModel(item){_isChecked=this.IsChecked};
 if(model.IsChecked==true){
_checkedItems.Add(model);
 PropertyChanged(this,newPropertyChangedEventArgs("CheckedItems"));
}
Children.Add(model);
}
Init();
}
}

 ///
 ///判断是否有子节点（逻辑是：如果只有一个临时子节点，说明没有真正的子节点）
 ///
 ///
 privateboolHasChildren(){
 return!(Children.Count==1&&Children[0]==_temp);
}

 publicObservableCollectionCheckedItems{
 get{
 return_checkedItems;
}
}

 publiceventPropertyChangedEventHandlerPropertyChanged;
}
}

5）创建WPF窗体

<Windowx:Class="DepartmentTreeView.MainWindow"
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 xmlns:local="clr-namespace:DepartmentTreeView"
 Title="MainWindow"Height="329"Width="212"FontFamily="Arial">
 <Window.Resources>
 <ObjectDataProviderx:Key="depProvider"ObjectType="{x:Typelocal:DepartmentViewModel}"MethodName="Create"/>
 <Stylex:Key="TreeViewItemStyle"TargetType="{x:TypeTreeViewItem}">
 <SetterProperty="IsExpanded"Value="{BindingPath=IsExpanded,Mode=TwoWay}"/>
 Style>
 <HierarchicalDataTemplatex:Key="CheckBoxItemTemplate"ItemsSource="{BindingChildren}">
 <StackPanelOrientation="Horizontal"Margin="0,2,0,0">
 <CheckBoxFocusable="False"IsChecked="{BindingIsChecked,Mode=TwoWay}"VerticalAlignment="Center"/>
 <ContentPresenterContent="{BindingDisplayText,Mode=OneWay}"Margin="2,0"/>
 StackPanel>
 HierarchicalDataTemplate>
 Window.Resources>
 <GridMargin="5">
 <Grid.RowDefinitions>
 <RowDefinition/>
 <RowDefinitionHeight="Auto"/>
 <RowDefinitionHeight="Auto"/>
 Grid.RowDefinitions>
 <TreeViewName="tvDepartment"Grid.Row="0"ItemContainerStyle="{StaticResourceTreeViewItemStyle}"ItemsSource="{BindingSource={StaticResourcedepProvider}}"ItemTemplate="{StaticResourceCheckBoxItemTemplate}"/>
 <TextBlockName="tbText"Margin="5"Grid.Row="1">当前选中项：<TextBlockText="{BindingSource={StaticResourcedepProvider},Path=CheckedItems.Count,Mode=OneWay,IsAsync=True}"/>TextBlock>
 <ButtonMargin="5"Grid.Row="2"Content="GetCheckedItems"Click="Button_Click"/>
 Grid>
 Window>

6）窗口的后置代码

usingSystem.Collections.Generic;
 usingSystem.Text;
 usingSystem.Windows;
 usingSystem.Windows.Data;
 usingSystem.Windows.Documents;
 usingSystem.ComponentModel;

 namespaceDepartmentTreeView{
 ///
 ///MainWindow.xaml的交互逻辑
 ///
 publicpartialclassMainWindow:Window{
 publicMainWindow(){
InitializeComponent();
}

 privatevoidButton_Click(objectsender,RoutedEventArgse){
 ObjectDataProviderprovider=FindResource("depProvider")asObjectDataProvider;
 ListfirstLevelItems=provider.DataasList;

ICollectionViewview=CollectionViewSource.GetDefaultView(firstLevelItems);
 DepartmentViewModelrootItem=view.CurrentItemasDepartmentViewModel;

 ListcheckedItems=CollectionViewSource.GetDefaultView(provider)asList;

 StringBuilderbuilder=newStringBuilder();
 foreach(DepartmentViewModelcheckIteminrootItem.CheckedItems){
builder.AppendLine(checkItem.DisplayText);
}
 MessageBox.Show("Checkeditems:/n"+builder.ToString());
}
}
}

好了，到此大功告成！！！

源代码：http://download.csdn.net/source/3253097