WPF 学习笔记《7》——Binding《5》

10. 数据提供程序

(1) XmlDataProvider

XmlDataProvider 允许我们直接将 XML 数据作为数据源，我们将前面章节的例子改成 XML 数据岛试试，注意此时我们已经不需要在代码中定义 Personal、PersonalList 类型。

 1 <Window x:Class="Learn.WPF.Window1"
 2   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4   Title="Window1">
 5   <Window.Resources>
 6 
 7     <XmlDataProvider x:Key="personals" XPath="Personals">
 8       <x:XData>
 9         <Personals xmlns="">
10           <Personal Name="Tom" Age="15" Sex="Male" />
11           <Personal Name="Mary" Age="11" Sex="Female" />
12           <Personal Name="Jack" Age="12" Sex="Male" />
13         </Personals>
14       </x:XData>
15     </XmlDataProvider>
16 
17   </Window.Resources>
18   <Grid>
19     <StackPanel DataContext="{StaticResource personals}">
20       <ListBox x:Name="listbox1" ItemsSource="{Binding XPath=*}">
21         <ListBox.ItemTemplate>
22           <DataTemplate>
23             <StackPanel Orientation="Horizontal">
24               <TextBlock Text="{Binding XPath=@Name}" />
25               <TextBlock>,</TextBlock>
26               <TextBlock Text="{Binding XPath=@Age}" />
27               <TextBlock>,</TextBlock>
28               <TextBlock Text="{Binding XPath=@Sex}" />
29             </StackPanel>
30           </DataTemplate>
31         </ListBox.ItemTemplate>
32       </ListBox>
33     </StackPanel>
34   </Grid>
35 </Window>

在资源中定义 XML 数据岛，注意 "Personals xmlns" 不能省略，另外采用 XPath 进行了绑定操作 (XPath 的语法可参考 MSDN 文档)。除了使用数据岛，我们还以使用 XML 数据文件。

Window1.xaml

 1 <Window x:Class="Learn.WPF.Window1"
 2   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4   xmlns:my="clr-namespace:Learn.WPF"
 5   Title="Window1">
 6   <Window.Resources>
 7 
 8     <XmlDataProvider x:Key="personals" Source="pack://siteOfOrigin:,,,/Personals.xml" 
 9       XPath="Personals" />
10   
11   </Window.Resources>
12   <Grid>
13     <StackPanel DataContext="{StaticResource personals}">
14       <ListBox x:Name="listbox1" ItemsSource="{Binding XPath=*}">
15         <ListBox.ItemTemplate>
16           <DataTemplate>
17             <StackPanel Orientation="Horizontal">
18               <TextBlock Text="{Binding XPath=@Name}" />
19               <TextBlock>,</TextBlock>
20               <TextBlock Text="{Binding XPath=@Age}" />
21               <TextBlock>,</TextBlock>
22               <TextBlock Text="{Binding XPath=@Sex}" />
23             </StackPanel>
24           </DataTemplate>
25         </ListBox.ItemTemplate>
26       </ListBox>
27     </StackPanel>
28   </Grid>
29 </Window>

Personals.xml

1 <?xml version="1.0" encoding="utf-8" ?>
2 <Personals xmlns="">
3   <Personal Name="Tom" Age="15" Sex="Male" />
4   <Personal Name="Mary" Age="11" Sex="Female" />
5   <Personal Name="Jack" Age="12" Sex="Male" />
6 </Personals>

在 Source 属性中指定 XML Uri。

当然，我们也可以在程序代码中通过 XmlDocument 来控制 XML 数据源。

Window1.xaml

 1 <Window x:Class="Learn.WPF.Window1"
 2   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4   Title="Window1">
 5   <Window.Resources>
 6 
 7     <XmlDataProvider x:Key="personals" />
 8 
 9   </Window.Resources>
10   <Grid>
11     <StackPanel DataContext="{StaticResource personals}">
12       <ListBox x:Name="listbox1" ItemsSource="{Binding XPath=*}">
13         <ListBox.ItemTemplate>
14           <DataTemplate>
15             <StackPanel Orientation="Horizontal">
16               <TextBlock Text="{Binding XPath=@Name}" />
17               <TextBlock>,</TextBlock>
18               <TextBlock Text="{Binding XPath=@Age}" />
19               <TextBlock>,</TextBlock>
20               <TextBlock Text="{Binding XPath=@Sex}" />
21             </StackPanel>
22           </DataTemplate>
23         </ListBox.ItemTemplate>
24       </ListBox>
25     </StackPanel>
26   </Grid>
27 </Window>
28 
29 Window1.xaml.cs
30 
31 public partial class Window1 : Window
32 {
33   public Window1()
34   {
35     InitializeComponent();
36 
37  var xml = new XmlDocument();
38     xml.Load("Personals.xml");
39 
40     var provider = this.FindResource("personals") as XmlDataProvider;
41     provider.Document = xml;
42     provider.XPath = "Personals";
43   }
44 }

逻辑代码只需修改 XmlDocument 即可自动同步显示到界面上。

protected void ButtonClick(object sender, RoutedEventArgs e)
{
  var provider = this.FindResource("personals") as XmlDataProvider;
  var xml = provider.Document;

  var mary = xml.SelectSingleNode("Personals/Personal[@Name=/"Mary/"]") as XmlElement;
  var age = Convert.ToInt32(mary.Attributes["Age"].Value);

  mary.Attributes["Age"].Value = (++age).ToString();
}

如果设置了 Source 属性，则放弃所有内联 XML 数据；如果设置了 Document 属性，则清除 Source 属性并放弃所有内联 XML 数据。
设置以下属性将隐式导致此 XmlDataProvider 对象刷新：Source、Document、XmlNamespaceManager 和 XPath。
在更改多个导致刷新的属性时，建议使用 DeferRefresh。

(2) ObjectDataProvider

ObjectDataProvider 比我们直接绑定对象有如下三个好处：

可以在 XAML 申明中使用构造参数。
绑定到源对象的方法上。
支持异步数据绑定。

我们先看看构造参数的使用。

Window1.xaml.cs

 1 enum Sex
 2 {
 3   Male,
 4   Female
 5 }
 6 
 7 class Personal
 8 {
 9   public string Name { get; private set; }
10   public int Age { get; private set; }
11   public Sex Sex { get; private set; }
12 
13   public Personal(string name, int age, Sex sex)
14   {
15     this.Name = name;
16     this.Age = age;
17     this.Sex = sex;
18   }
19 }
20 
21 public partial class Window1 : Window
22 {
23   public Window1()
24   {
25     InitializeComponent();
26   }
27 }

Window1.xaml

 1 <Window x:Class="Learn.WPF.Window1"
 2   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4   xmlns:my="clr-namespace:Learn.WPF"
 5   xmlns:sys="clr-namespace:System;assembly=mscorlib"
 6   Title="Window1">
 7   <Window.Resources>
 8     
 9     <ObjectDataProvider x:Key="personal" ObjectType="{x:Type my:Personal}">
10       <ObjectDataProvider.ConstructorParameters>
11         <sys:String>Tom</sys:String>
12         <sys:Int32>15</sys:Int32>
13         <my:Sex>Male</my:Sex>
14       </ObjectDataProvider.ConstructorParameters>
15     </ObjectDataProvider>
16     
17   </Window.Resources>
18   <Grid>
19     <StackPanel DataContext="{StaticResource personal}">
20       <Label Content="{Binding Name}" />
21       <Label Content="{Binding Age}" />
22       <Label Content="{Binding Sex}" />
23     </StackPanel>
24   </Grid>
25 </Window>

接下来，我们尝试绑定到一个方法上。
Window1.xaml.cs

 1 class PersonalList : ObservableCollection<Personal>
 2 {
 3   public PersonalList GetPersonals()
 4   {
 5     this.Add(new Personal("Tom", 15, Sex.Male));
 6     this.Add(new Personal("Mary", 11, Sex.Female));
 7     this.Add(new Personal("Jack", 13, Sex.Male));
 8 
 9     return this;
10   }
11 }
12 
13 public partial class Window1 : Window
14 {
15   public Window1()
16   {
17     InitializeComponent();
18   }
19 }

Window1.xaml

 1 <Window x:Class="Learn.WPF.Window1"
 2   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4   xmlns:my="clr-namespace:Learn.WPF"
 5   xmlns:sys="clr-namespace:System;assembly=mscorlib"
 6   Title="Window1">
 7   <Window.Resources>
 8     
 9     <ObjectDataProvider x:Key="personals" ObjectType="{x:Type my:PersonalList}" 
10       MethodName="GetPersonals" />
11     
12   </Window.Resources>
13   <Grid>
14     <StackPanel DataContext="{StaticResource personals}">
15       <ListBox x:Name="listbox1" ItemsSource="{Binding}">
16         <ListBox.ItemTemplate>
17           <DataTemplate>
18             <StackPanel Orientation="Horizontal">
19               <TextBlock Text="{Binding Path=Name}" />
20               <TextBlock>,</TextBlock>
21               <TextBlock Text="{Binding Path=Age}" />
22               <TextBlock>,</TextBlock>
23               <TextBlock Text="{Binding Path=Sex}" />
24             </StackPanel>
25           </DataTemplate>
26         </ListBox.ItemTemplate>
27       </ListBox>
28     </StackPanel>
29   </Grid>
30 </Window>

和构造方法参数一样，我们也可以向方法提供参数。

Window1.xaml.cs

 1 class PersonalList : ObservableCollection<Personal>
 2 {
 3   public IEnumerable<Personal> GetPersonals(int top)
 4   {
 5     this.Add(new Personal("Tom", 15, Sex.Male));
 6     this.Add(new Personal("Mary", 11, Sex.Female));
 7     this.Add(new Personal("Jack", 13, Sex.Male));
 8 
 9     return this.Take(top);
10   }
11 }

Window1.xaml

1 <ObjectDataProvider x:Key="personals" ObjectType="{x:Type my:PersonalList}" MethodName="GetPersonals">
2   <ObjectDataProvider.MethodParameters>
3     <sys:Int32>2</sys:Int32>
4   </ObjectDataProvider.MethodParameters>
5 </ObjectDataProvider>

posted @ 2011-08-22 16:51 徐文峰阅读(280) 评论(0) 收藏举报

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WPF 学习笔记《7》——Binding《5》

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