<Page    x:Class="Windows81.Binding.DataContextChanged"    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"    xmlns:local="using:Windows81.Binding"    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"    mc:Ignorable="d">    <Grid Background="Transparent">        <StackPanel Margin="120 0 0 0">            <TextBlock Name="lblMsg" FontSize="14.667" />                        <Button x:Name="btnChange" Content="改变数据上下文" Click="btnChange_Click" Margin="0 10 0 0" />                        <ListBox x:Name="listBox" ItemsSource="{Binding}" DataContextChanged="listBox_DataContextChanged" Margin="0 10 0 0" />        </StackPanel>    </Grid></Page>

/* * DataContextChanged - FrameworkElement 的 DataContext 发生变化时触发的事件 *  *  * 关于绑定的基础请参见： * http://www.cnblogs.com/webabcd/archive/2013/08/19/3267115.html * http://www.cnblogs.com/webabcd/archive/2013/08/22/3274099.html * http://www.cnblogs.com/webabcd/archive/2013/08/26/3281822.html * http://www.cnblogs.com/webabcd/archive/2013/08/29/3288304.html */using System;using System.Collections.Generic;using Windows.UI.Xaml;using Windows.UI.Xaml.Controls;namespace Windows81.Binding{    public sealed partial class DataContextChanged : Page    {        public DataContextChanged()        {            this.InitializeComponent();            this.Loaded += new RoutedEventHandler(DataContextChanged_Loaded);        }        void DataContextChanged_Loaded(object sender, RoutedEventArgs e)        {            // 指定数据上下文            listBox.DataContext = new List<string> { "a", "b", "c" };        }        private void btnChange_Click(object sender, RoutedEventArgs e)        {            // 修改数据上下文            listBox.DataContext = new List<string> { "a", "b", new Random().Next(0, 1000).ToString().PadLeft(3, ‘0‘) };        }        private void listBox_DataContextChanged(FrameworkElement sender, DataContextChangedEventArgs args)        {            /*             * FrameworkElement.DataContextChanged - 数据上下文发生改变后所触发的事件             */            // 数据上下文发生改变后            lblMsg.Text = "数据源发生改变：" + DateTime.Now.ToString("hh:mm:ss");                    }    }}

<Page    x:Class="Windows81.Binding.TargetNullValueFallbackValue"    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"    xmlns:local="using:Windows81.Binding"    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"    mc:Ignorable="d">    <Grid Background="Transparent">        <StackPanel Name="stackPanel" Margin="120 0 0 0">            <!--                FallbackValue - 当绑定失败（无法返回值）的时候所需要显示的值            -->            <TextBlock FontSize="14.667" Text="{Binding Path=xxx, FallbackValue=http://www.mamicode.com/‘绑定失败时的默认值‘}" />            <!--                TargetNullValue - 当绑定数据为 null 时所需要显示的值            -->            <TextBlock FontSize="14.667" Text="{Binding Path=Name, TargetNullValue=http://www.mamicode.com/‘绑定返回值为 null‘}" Margin="0 10 0 0" />                    </StackPanel>    </Grid></Page>

/* * TargetNullValue - 当绑定数据为 null 时所需要显示的值  * FallbackValue - 当绑定失败（无法返回值）的时候所需要显示的值  *  *  * 关于绑定的基础请参见： * http://www.cnblogs.com/webabcd/archive/2013/08/19/3267115.html * http://www.cnblogs.com/webabcd/archive/2013/08/22/3274099.html * http://www.cnblogs.com/webabcd/archive/2013/08/26/3281822.html * http://www.cnblogs.com/webabcd/archive/2013/08/29/3288304.html */using Windows.UI.Xaml.Controls;using Windows.UI.Xaml.Navigation;namespace Windows81.Binding{    public sealed partial class TargetNullValueFallbackValue : Page    {        public TargetNullValueFallbackValue()        {            this.InitializeComponent();        }        protected override void OnNavigatedTo(NavigationEventArgs e)        {            stackPanel.DataContext = new TargetNullValueTest { Name = null };        }    }    public sealed class TargetNullValueTest    {        public string Name { get; set; }    }}

<Page    x:Class="Windows81.Binding.UpdateSourceTrigger"    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"    xmlns:local="using:Windows81.Binding"    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"    mc:Ignorable="d">    <Grid Background="Transparent">        <StackPanel Name="stackPanel" Margin="120 0 0 0">            <TextBlock Name="lblMsg" />                        <!--                UpdateSourceTrigger - UI 上数据更新的触发方式                    Default - 失去焦点后触发                    PropertyChanged - 属性值发生改变后触发                    Explicit - 需要通过 BindingExpression.UpdateSource() 显示触发            -->                        <TextBox Text="{Binding Text, Mode=TwoWay, ElementName=lblMsg, UpdateSourceTrigger=Default}" Margin="0 10 0 0" />            <TextBox Text="{Binding Text, Mode=TwoWay, ElementName=lblMsg, UpdateSourceTrigger=PropertyChanged}" Margin="0 10 0 0" />            <TextBox Name="txtExplicit" Text="{Binding Text, Mode=TwoWay, ElementName=lblMsg, UpdateSourceTrigger=Explicit}" Margin="0 10 0 0" />                        <Button Name="btnBinding" Content="显示触发更新" Click="btnBinding_Click" Margin="0 10 0 0" />        </StackPanel>    </Grid></Page>

/* * UpdateSourceTrigger - UI 上数据更新的触发方式 *     Default - 失去焦点后触发 *     PropertyChanged - 属性值发生改变后触发 *     Explicit - 需要通过 BindingExpression.UpdateSource() 显示触发 *  *  * 关于绑定的基础请参见： * http://www.cnblogs.com/webabcd/archive/2013/08/19/3267115.html * http://www.cnblogs.com/webabcd/archive/2013/08/22/3274099.html * http://www.cnblogs.com/webabcd/archive/2013/08/26/3281822.html * http://www.cnblogs.com/webabcd/archive/2013/08/29/3288304.html */using Windows.UI.Xaml;using Windows.UI.Xaml.Controls;using Windows.UI.Xaml.Data;namespace Windows81.Binding{    public sealed partial class UpdateSourceTrigger : Page    {        public UpdateSourceTrigger()        {            this.InitializeComponent();        }        private void btnBinding_Click(object sender, RoutedEventArgs e)        {            // 显示触发 txtExplicit 的数据更新            BindingExpression be = txtExplicit.GetBindingExpression(TextBox.TextProperty);            be.UpdateSource();        }    }}