Easy Binding(DataContext，TwoWay)

偏执的太偏执、 2022-01-06 22:31 109阅读 0赞

下载示例： [http://files.cnblogs.com/civ3/Easy%20Binding.rar][http_files.cnblogs.com_civ3_Easy_20Binding.rar]  
双向绑定在WPF中非常方便。

![None.gif][] < Window  x:Class ="SDKSample.BindingTest"   
![None.gif][]    xmlns ="http://schemas.microsoft.com/winfx/avalon/2005"   
![None.gif][]    xmlns:x ="http://schemas.microsoft.com/winfx/xaml/2005"   
![None.gif][]    Title ="BindingTest for fun ;)"  Name ="rootd"   
![None.gif][]     >   
![None.gif][]   < StackPanel  Name ="sp" >   
![None.gif][]     < StackPanel .Resources >   
![None.gif][]       < XmlDataProvider  x:Key ="BookData"  XPath ="/Books"  Source ="book.xml" >   
![None.gif][]       </ XmlDataProvider >   
![None.gif][]        
![None.gif][]       < DataTemplate  x:Key ="BookDataTemplate" >   
![None.gif][]         < TextBlock  FontSize ="12"  Foreground ="Red" >   
![None.gif][]           < TextBlock .Text >   
![None.gif][]             < Binding  XPath ="Title" />   
![None.gif][]           </ TextBlock.Text >   
![None.gif][]         </ TextBlock >   
![None.gif][]       </ DataTemplate >   
![None.gif][]        
![None.gif][]     </ StackPanel.Resources >   
![None.gif][]      
![None.gif][]     < ListBox  
![None.gif][]   Width ="400"  Height ="300"  Background ="Honeydew"   
![None.gif][]  ItemsSource ="\{Binding Source=\{StaticResource BookData\}, XPath=Book\}"   
![None.gif][]  ItemTemplate ="\{StaticResource BookDataTemplate\}"  SelectionChanged ="onChanged"   
![None.gif][]   />   
![None.gif][]     < TextBox  Name ="inputer"  Text ="\{Binding XPath=Title,   
![None.gif][]  
![None.gif][]Mode=TwoWay,UpdateSourceTrigger=PropertyChanged\}" />   
![None.gif][]  
![None.gif][]   </ StackPanel >   
![None.gif][] </ Window >

注意不声明inputer的Source，而是当改变选取listbox项时：

![None.gif][]          void  onChanged( object  sender, RoutedEventArgs eas)  
![ExpandedBlockStart.gif][None.gif]![ContractedBlock.gif][None.gif]         ![dot.gif][] \{  
![InBlock.gif][None.gif]            TextBox inputer=this.FindName("inputer") as TextBox;  
![InBlock.gif][None.gif]            inputer.DataContext = (sender as ListBox).SelectedItem;  
![ExpandedBlockEnd.gif][None.gif]        \}

我理解是这样实现的：  
listItem对应（数据）XmlNode，初始化时，listItem用模版显示Node的Title文本。  
当改变选取listbox项时  
通过DataContext（数据上下文）属性，改变数据游标位置，从而改变inputer的绑定源。  
由于inputer的绑定模式是双向的，所以手工输入改变inputer的文本时

（UpdateSourceTrigger=PropertyChanged），同步更新绑定源。  
这时你会发现，listbox的显示也同步发生改变。

感觉DataContext是个很神奇的东西。

澄清几个概念：  
数据源：XmlDataProvider的Source——book.xml  
IO级的理解  
绑定源：Binding Source=\{StaticResource BookData\}  
运行时的理解

小发现：  
FindName——有DOM基础的同志一定会回忆起getElementById或selectSingleNodeById  
 (sender as ListBox)——有面向对象基础的同志都明白这叫“装箱”，我喜欢一致地用C\#

附：book.xml  
要放到exe的相同路径，并include到project中，惑之。

![None.gif][] < Books >   
![None.gif][]         < Book  ISBN ="0-7356-0562-9"  Stock ="in" >   
![None.gif][]           < Title > XML in Action </ Title >   
![None.gif][]           < Summary > XML Web Technology </ Summary >   
![None.gif][]         </ Book >   
![None.gif][]         < Book  ISBN ="0-7356-1370-2"  Stock ="in" >   
![None.gif][]           < Title > Programming Microsoft Windows With C\# </ Title >   
![None.gif][]           < Summary > C\# Programming using the .NET Framework </ Summary >   
![None.gif][]         </ Book >   
![None.gif][]         < Book  ISBN ="0-7356-1288-9"  Stock ="out" >   
![None.gif][]           < Title > Inside C\# </ Title >   
![None.gif][]           < Summary > C\# Language Programming </ Summary >   
![None.gif][]         </ Book >   
![None.gif][]         < Book  ISBN ="0-7356-1377-X"  Stock ="in" >   
![None.gif][]           < Title > Introducing Microsoft .NET </ Title >   
![None.gif][]           < Summary > Overview of .NET Technology </ Summary >   
![None.gif][]         </ Book >   
![None.gif][]         < Book  ISBN ="0-7356-1448-2"  Stock ="out" >   
![None.gif][]           < Title > Microsoft C\# Language Specifications </ Title >   
![None.gif][]           < Summary > The C\# language definition </ Summary >   
![None.gif][]         </ Book >   
![None.gif][] </ Books >

转载于:https://www.cnblogs.com/civ3/archive/2006/02/12/329188.html

[http_files.cnblogs.com_civ3_Easy_20Binding.rar]: http://files.cnblogs.com/civ3/Easy%20Binding.rar
[None.gif]: 
[dot.gif]: /images/20211227/b15d40b245464c1797882fc7702531ca.png