稳扎稳打Silverlight(15) - 2.0数据之一次绑定, 单向绑定, 双向绑定, INotifyPropertyChanged, 数据转换

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稳扎稳打Silverlight(15) - 2.0数据之一次绑定,单向绑定,双向绑定,INotifyPropertyChanged,数据转换,数据验证

作者： webabcd


介绍
Silverlight 2.0 数据绑定：
    Binding - 将绑定目标对象的属性与数据源联接起来
        Source - 绑定的数据源
        Mode - 绑定的数据流的方向 [System.Windows.Data.BindingMode枚举]
            BindingMode.OneTime - 一次绑定。创建绑定时一次性地更新绑定目标对象的属性
            BindingMode.OneWay - 单向绑定（默认值）。数据源的改变会自动通知到绑定目标对象的属性
            BindingMode.TwoWay - 双向绑定。数据源或绑定目标对象的属性的值发生改变时会互相通知。显然，做数据验证的话一定要是双向绑定
        Path - 需要绑定的属性名称
        NotifyOnValidationError - 产生验证错误时是否触发 BindingValidationError 事件。默认值为 false
        ValidatesOnExceptions - 产生验证错误时绑定引擎是否要报告错误。默认值为 false
    INotifyPropertyChanged - 向客户端发出某一属性值已更改的通知
    IValueConverter - 值转换接口，将一个类型的值转换为另一个类型的值。它提供了一种将自定义逻辑应用于绑定的方式
        Convert - 正向转换器。将值从数据源传给绑定目标时，数据绑定引擎会调用此方法
        ConvertBack - 反向转换器。将值从绑定目标传给数据源时，数据绑定引擎会调用此方法
    BindingValidationError - 出现验证错误或解决上次验证错误则触发此事件


在线DEMO
http://www.voidcn.com/article/p-ounmxjds-tq.html  


示例
1、NotifyProperty.xaml（演示INotifyPropertyChanged）

<UserControl x:Class="Silverlight20.Data.NotifyProperty"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
        <StackPanel HorizontalAlignment="Left">

                <!--
                Binding - 将绑定目标对象的属性与数据源联接起来（本例为将 Ellipse的Fill属性 与 MyColor的Brush属性 相联）
                Mode - Binding 的扩展属性之一，默认为 OneWay（单向绑定），即数据源的改变会自动通知到绑定目标对象的属性
                -->
                <Ellipse x:Name="ellipse" Width="100" Height="50" Fill="{Binding Brush,Mode=OneWay}" MouseLeftButtonDown="ellipse_MouseLeftButtonDown" />

        </StackPanel>
</UserControl>

 

NotifyProperty.xaml.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Net;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Animation;

using System.Windows.Shapes;

using System.ComponentModel;

namespace Silverlight20.Data

{

         public partial class NotifyProperty : UserControl

        {

                MyColor _myColor;

                 public Notifyproperty()

                {

                        InitializeComponent();

                         this.Loaded += new RoutedEventHandler(NotifyProperty_Loaded);

                }

                 void NotifyProperty_Loaded( object sender,RoutedEventArgs e)

                {

                        _myColor = new MyColor { Brush = new SolidColorBrush(Colors.Red) };

                         // DataContext - FrameworkElement 做数据绑定时的数据上下文

                         // 将 MyColor 对象绑定到 Ellipse

                        ellipse.DataContext = _myColor;

                }

                 private void ellipse_MouseLeftButtonDown( object sender,MouseButtonEventArgs e)

                {

                         // 鼠标按下后修改 MyColor 对象的属性

                         // 如果MyColor实现了INotifyPropertyChanged接口，并且绑定目标的BindingMode为OneWay或者TwoWay的话则会自动通知到绑定目标

                         if (_myColor.Brush.Color == Colors.Red)

                                _myColor.Brush = new SolidColorBrush(Colors.Green);

                         else

                                _myColor.Brush = new SolidColorBrush(Colors.Red);

                }

        }

         /*

         * INotifyPropertyChanged - 向客户端发出某一属性值已更改的通知

         * 使用 OneWay 或者 TwoWay 的话必须要实现 INotifyPropertyChanged 接口

        */

         public class MyColor : INotifyPropertyChanged

        {

                 private SolidColorBrush _brush;

                 public SolidColorBrush Brush

                {

                        get { return _brush; }

                        set

                        {

                                _brush = value;

                                 if (PropertyChanged != null)

                                {

                                         // 触发 PropertyChanged 事件，事件参数为属性名称

                                        PropertyChanged( this,new PropertyChangedEventArgs( "Brush"));

                                }

                        }

                }

                 // 声明一个 PropertyChanged 事件

                 public event PropertyChangedEventHandler PropertyChanged;

        }

}

 

2、Conversion.xaml（演示数据转换）

<!--引用转换器所在的命名空间-->
<UserControl x:Class="Silverlight20.Data.Conversion"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:custom="clr-namespace:Silverlight20.Data">
        
        <UserControl.Resources>
        
                <!--在资源中声明转换器-->
                <custom:ColorEnumToBrush x:Key="converter" />
                
        </UserControl.Resources>
        
        <StackPanel HorizontalAlignment="Left">

                <!--
                Converter - 用于指定转换器
                ConverterParameter - 转换器所使用的参数
                ConverterCulture - 转换器所使用的区域信息
                -->
                <Ellipse x:Name="ellipse" Width="100" Height="50" MouseLeftButtonDown="ellipse_MouseLeftButtonDown"    
                        Fill="{Binding ColorEnum,Converter={StaticResource converter},ConverterParameter=10}"    
                />

        </StackPanel>
</UserControl>

 

Conversion.xaml.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Net;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Animation;

using System.Windows.Shapes;

using System.ComponentModel;

using System.Windows.Data;

namespace Silverlight20.Data

{

         public partial class Conversion : UserControl

        {

                MyColorEnum _myColorEnum;

                 public Conversion()

                {

                        InitializeComponent();

                         this.Loaded += new RoutedEventHandler(Conversion_Loaded);

                }

                 void Conversion_Loaded( object sender,RoutedEventArgs e)

                {

                        _myColorEnum = new MyColorEnum() { ColorEnum = ColorEnum.Red };

                         // DataContext - FrameworkElement 做数据绑定时的数据上下文

                         // 将 MyColorEnum 对象绑定到 Ellipse

                        ellipse.DataContext = _myColorEnum;

                }

                 private void ellipse_MouseLeftButtonDown( object sender,MouseButtonEventArgs e)

                {

                         // 鼠标按下后修改 MyColorEnum 对象的属性

                         if (_myColorEnum.ColorEnum == ColorEnum.Red)

                                _myColorEnum.ColorEnum = ColorEnum.Green;

                         else

                                _myColorEnum.ColorEnum = ColorEnum.Red;

                }

        }

         /*

         * IValueConverter - 值转换接口，将一个类型的值转换为另一个类型的值。它提供了一种将自定义逻辑应用于绑定的方式

         *         Convert - 正向转换器。将值从数据源传给绑定目标时，数据绑定引擎会调用此方法

         *         ConvertBack - 反向转换器。将值从绑定目标传给数据源时，数据绑定引擎会调用此方法

        */

         public class ColorEnumToBrush : IValueConverter

        {

                 /// <summary>

                 /// 正向转换器。将值从数据源传给绑定目标时，数据绑定引擎会调用此方法

                 /// </summary>

                 /// <param name="value">转换之前的值</param>

                 /// <param name="targettype">转换之后的类型</param>

                 /// <param name="parameter">转换器所使用的参数</param>

                 /// <param name="culture">转换器所使用的区域信息</param>

                 /// <returns>转换后的值</returns>

                 public object Convert( object value,Type targettype,object parameter,System.Globalization.CultureInfo culture)

                {

                         // 将 ColorEnum 类型的值转换为 SolidColorBrush 类型的值

                         // parameter == 10

                        ColorEnum color = (ColorEnum)value;

                        SolidColorBrush brush = new SolidColorBrush(Colors.Red);

                         if (color == ColorEnum.Green)

                                brush = new SolidColorBrush(Colors.Green);

                         return brush;

                }

                 /// <summary>

                 /// 反向转换器。将值从绑定目标传给数据源时，数据绑定引擎会调用此方法

                 /// </summary>

                 /// <param name="value">转换之前的值</param>

                 /// <param name="targettype">转换之后的类型</param>

                 /// <param name="parameter">转换器所使用的参数</param>

                 /// <param name="culture">转换器所使用的区域信息</param>

                 /// <returns>转换后的值</returns>

                 public object ConvertBack( object value,System.Globalization.CultureInfo culture)

                {

                         return null;

                }

        }

         /*

         * INotifyPropertyChanged - 向客户端发出某一属性值已更改的通知

         * 使用 OneWay 或者 TwoWay 的话必须要实现 INotifyPropertyChanged 接口

        */

         public class MyColorEnum : INotifyPropertyChanged

        {

                 private ColorEnum _colorEnum;

                 public ColorEnum ColorEnum

                {

                        get { return _colorEnum; }

                        set

                        {

                                _colorEnum = value;

                                 if (PropertyChanged != null)

                                {

                                         // 触发 PropertyChanged 事件，事件参数为属性名称

                                        PropertyChanged( this,new PropertyChangedEventArgs( "ColorEnum"));

                                }

                        }

                }

                 // 声明一个 PropertyChanged 事件

                 public event PropertyChangedEventHandler PropertyChanged;

        }

         /// <summary>

         /// 自定义的 ColorEnum 枚举

         /// </summary>

         public enum ColorEnum

        {

                Red,

                Green

        }

}

 

 

3、Validation.xaml（演示数据验证）

<!--引用验证类所在的命名空间-->
<UserControl x:Class="Silverlight20.Data.Validation"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:custom="clr-namespace:Silverlight20.Data">
        
        <!--
        BindingValidationError - 出现验证错误或解决上次验证错误则触发此事件
        -->
        <StackPanel HorizontalAlignment="Left" BindingValidationError="StackPanel_BindingValidationError" >
                
                <StackPanel.Resources>
                
                        <!--在资源中声明验证类-->
                        <custom:MyValidation x:Name="myValidation"/>
                        
                </StackPanel.Resources>
                
                <TextBox x:Name="textBox" Width="200" Margin="5">
                        <TextBox.Text>
                        
                                <!--
                                Binding - 将绑定目标对象的属性与数据源联接起来
                                        Source - 绑定的数据源
                                        Mode - 绑定的数据流的方向 [System.Windows.Data.BindingMode枚举]
                                                BindingMode.OneTime - 一次绑定。创建绑定时一次性地更新绑定目标对象的属性
                                                BindingMode.OneWay - 单向绑定（默认值）。数据源的改变会自动通知到绑定目标对象的属性
                                                BindingMode.TwoWay - 双向绑定。数据源或绑定目标对象的属性的值发生改变时会互相通知。显然，做数据验证的话一定要是双向绑定
                                        Path - 需要绑定的属性名称
                                        NotifyOnValidationError - 产生验证错误时是否触发 BindingValidationError 事件。默认值为 false
                                        ValidatesOnExceptions - 产生验证错误时绑定引擎是否要报告错误。默认值为 false
                                -->
                                <Binding    
                                        Source="{StaticResource myValidation}"    
                                        Mode="TwoWay"    
                                        Path="Count"
                                        NotifyOnValidationError="True"    
                                        ValidatesOnExceptions="True"
                                />
                                        
                        </TextBox.Text>
                </TextBox>
                
                <TextBox x:Name="textBox2" Width="200"    Margin="5" />
                        
        </StackPanel>
        
</UserControl>

 

Validation.xaml.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Net;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Animation;

using System.Windows.Shapes;

using System.Text.RegularExpressions;

namespace Silverlight20.Data

{

         public partial class Validation : UserControl

        {

                 public Validation()

                {

                        InitializeComponent();

                }

                 private void StackPanel_BindingValidationError( object sender,ValidationErrorEventArgs e)

                {

                         // ValidationErrorEventArgs - 用于提供 BindingValidationError 事件的一些信息

                         //         ValidationErrorEventArgs.Action - 验证状态

                         //         ValidationErrorEventArgs.Error - 触发 BindingValidationError 事件的错误信息

                         //         ValidationErrorEventArgs.Handled - 标记该路由事件是否已被处理

                         // ValidationErrorEventAction.Added - 因为出现验证错误而触发此事件

                         // ValidationErrorEventAction.Removed - 因为解决上次验证错误而触发此事件

                         if (e.Action == ValidationErrorEventAction.Added)

                        {

                                textBox.Background = new SolidColorBrush(Colors.Red);

                                textBox.Text = e.Error.Exception.Message;

                        }

                         else if (e.Action == ValidationErrorEventAction.Removed)

                        {

                                textBox.Background = new SolidColorBrush(Colors.White);

                        }

                }

        }

         /// <summary>

         /// 验证类。验证是否为正整数

         /// </summary>

         public class MyValidation

        {

                 private string _count;

                 public string Count

                {

                        get { return _count; }

                        set

                        {

                                 if (!Regex.IsMatch(value,@"^\d+$"))

                                {

                                         // 绑定引擎可以报告由属性的 setter 抛出的异常，也可以报告由转换器（IValueConverter）抛出的异常

                                         throw new Exception( "必须是正整数");

                                }

                                _count = value;

                        }

                }

        }

}

 

 

OK
[源码下载]