WPF之HierarchicalDataTemplate

HierarchicalDataTemplate顾名思义，分层数据模板，就是用来定义分层数据样式的模板，一般多用于MenuItem和TreeViewItem

包含几个重要属性

DataType指定模板用于哪种数据类型

ItemsSource指定该类数据的子集，即下一层显示那些数据

内容 指定数据如何显示 绑定哪个属性

MSDN上的一个例子:

public class League
    {
        public League(string name)
        {
            _name = name;
            _divisions = new List<Division>();
        }


        string _name;

        public string Name { get { return _name; } }

        List<Division> _divisions;
        public List<Division> Divisions { get { return _divisions; } }

    }
    public class Division
    {
        public Division(string name)
        {
            _name = name;
            _teams = new List<Team>();

        }

        string _name;

        public string Name { get { return _name; } }

        List<Team> _teams;

        public List<Team> Teams { get { return _teams; } }

    }

    public class Team
    {
        public Team(string name)
        {
            _name = name;
        }

        string _name;

        public string Name { get { return _name; } }
    }

    public class ListLeagueList : List<League>
    {
        public ListLeagueList()
        {
            League l;
            Division d;

            Add(l = new League("League A"));
            l.Divisions.Add((d = new Division("Division A")));
            d.Teams.Add(new Team("Team I"));
            d.Teams.Add(new Team("Team II"));
            d.Teams.Add(new Team("Team III"));
            d.Teams.Add(new Team("Team IV"));
            d.Teams.Add(new Team("Team V"));
            l.Divisions.Add((d = new Division("Division B")));
            d.Teams.Add(new Team("Team Blue"));
            d.Teams.Add(new Team("Team Red"));
            d.Teams.Add(new Team("Team Yellow"));
            d.Teams.Add(new Team("Team Green"));
            d.Teams.Add(new Team("Team Orange"));
            l.Divisions.Add((d = new Division("Division C")));
            d.Teams.Add(new Team("Team East"));
            d.Teams.Add(new Team("Team West"));
            d.Teams.Add(new Team("Team North"));
            d.Teams.Add(new Team("Team South"));
            Add(l = new League("League B"));
            l.Divisions.Add((d = new Division("Division A")));
            d.Teams.Add(new Team("Team 1"));
            d.Teams.Add(new Team("Team 2"));
            d.Teams.Add(new Team("Team 3"));
            d.Teams.Add(new Team("Team 4"));
            d.Teams.Add(new Team("Team 5"));
            l.Divisions.Add((d = new Division("Division B")));
            d.Teams.Add(new Team("Team Diamond"));
            d.Teams.Add(new Team("Team Heart"));
            d.Teams.Add(new Team("Team Club"));
            d.Teams.Add(new Team("Team Spade"));
            l.Divisions.Add((d = new Division("Division C")));
            d.Teams.Add(new Team("Team Alpha"));
            d.Teams.Add(new Team("Team Beta"));
            d.Teams.Add(new Team("Team Gamma"));
            d.Teams.Add(new Team("Team Delta"));
            d.Teams.Add(new Team("Team Epsilon"));
        }

        public League this[string name]
        {
            get
            {
                foreach (League l in this)
                    if (l.Name == name)
                        return l;

                return null;
            }
        }


    }

<!--<SnippetHDT>-->
<Window x:Class="SDKSample.Window1"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Title="HierarchicalDataTemplate Sample"
  xmlns:src="clr-namespace:SDKSample">
  <DockPanel>
    <DockPanel.Resources>
      <src:ListLeagueList x:Key="MyList"/>

      <HierarchicalDataTemplate DataType    = "{x:Type src:League}"
                                ItemsSource = "{Binding Path=Divisions}">
          
        <TextBlock Text="{Binding Path=Name}"/>
      </HierarchicalDataTemplate>

      <HierarchicalDataTemplate DataType    = "{x:Type src:Division}"
                                ItemsSource = "{Binding Path=Teams}">
        <TextBlock Text="{Binding Path=Name}"/>
      </HierarchicalDataTemplate>

      <DataTemplate DataType="{x:Type src:Team}">
        <TextBlock Text="{Binding Path=Name}"/>
      </DataTemplate>
    </DockPanel.Resources>

    <Menu Name="menu1" DockPanel.Dock="Top" Margin="10,10,10,10">
        <MenuItem Header="My Soccer Leagues"
                  ItemsSource="{Binding Source={StaticResource MyList}}" />
    </Menu>

    <TreeView>
      <TreeViewItem ItemsSource="{Binding Source={StaticResource MyList}}" Header="My Soccer Leagues" />
    </TreeView>

  </DockPanel>
</Window>

这个例子的数据源是一个分层的List对象，下面一个例子的数据源是一个XML文件，大体相同，不同的地方是需要先实例化一个XmlDataProvider用来获取XML的内容，绑定的时候用的不是Path，而是XPath属性，给控件绑定属性的时候属性名加@(加@的是属性Attribute 不加的是子级元素)

<?xml version="1.0" encoding="utf-8" ?>
<Data xmlns="">
  <Grade Name="初一">
    <Class Name="1班">
      <Group Name="1-1-1组"></Group>
      <Group Name="1-1-2组"></Group>
      <Group Name="1-1-3组"></Group>
    </Class>
    <Class Name="2班">
      <Group Name="1-2-1组"></Group>
      <Group Name="1-2-2组"></Group>
      <Group Name="1-2-3组"></Group>
    </Class>
    <Class Name="3班">
      <Group Name="1-3-1组"></Group>
      <Group Name="1-3-2组"></Group>
      <Group Name="1-3-3组"></Group>
    </Class>
  </Grade>
  <Grade Name="初二">
    <Class Name="21班">
      <Group Name="2-1-1组"></Group>
      <Group Name="2-1-2组"></Group>
      <Group Name="2-1-3组"></Group>
    </Class>
    <Class Name="22班">
      <Group Name="2-2-1组"></Group>
      <Group Name="2-2-2组"></Group>
      <Group Name="2-2-3组"></Group>
    </Class>
    <Class Name="23班">
      <Group Name="2-3-1组"></Group>
      <Group Name="2-3-2组"></Group>
      <Group Name="2-3-3组"></Group>
    </Class>
  </Grade>
  <Grade Name="初三">
    <Class Name="31班">
      <Group Name="3-1-1组"></Group>
      <Group Name="3-1-2组"></Group>
      <Group Name="3-1-3组"></Group>
    </Class>
    <Class Name="32班">
      <Group Name="3-2-1组"></Group>
      <Group Name="3-2-2组"></Group>
      <Group Name="3-2-3组"></Group>
    </Class>
    <Class Name="33班">
      <Group Name="3-3-1组"></Group>
      <Group Name="3-3-2组"></Group>
      <Group Name="3-3-3组"></Group>
    </Class>
  </Grade>
</Data>

<XmlDataProvider x:Key="Data2" Source="Data.xml" XPath="Data/Grade"/>

        <HierarchicalDataTemplate DataType="Grade" ItemsSource="{Binding XPath= Class}">
            <TextBlock Text="{Binding XPath=@Name}"/>
        </HierarchicalDataTemplate>
        <HierarchicalDataTemplate DataType="Class" ItemsSource="{Binding XPath=Group}">
            <RadioButton Content="{Binding XPath=@Name}" GroupName="gr"/>
        </HierarchicalDataTemplate>
        <HierarchicalDataTemplate DataType="Group" ItemsSource="{Binding XPath=Student}">
            <CheckBox Content="{Binding XPath=@Name}"/>
        </HierarchicalDataTemplate>

<TreeView Margin="5" ItemsSource="{Binding Source={StaticResource Data2}}"></TreeView>

也试过递归方式给TreeView添加节点

void LoadXmlToTree(XElement root,TreeViewItem item)
        {
            if (root != null)
            {
                foreach (XElement xe in root.Elements())
                {
                    TreeViewItem item2 = new TreeViewItem();
                    item2.Header = xe.Attribute("Name").Value.ToString();
                    item.Items.Add(item2);
                    LoadXmlToTree(xe,item2);
                }
            }
        }

明显不如模板使用起来方便，但是现在的理解还处于初级阶段，只是简单的套使用方法，知其然，不知其所以然，还有待更进一步的理解，毕竟真正理解透了，原理清楚了，才能更灵活的应用。

注：Dictionary类型的需要用values属性

参考 MSDN 《深入浅出WPF》第11章