4.Binding类之转化器和验证规则
转化器IValueConverter接口
Binding类还有一个Converter属性，其实，它是一个IValueConverter接口。它的主要作用是：前后端建立绑定时，定义一套自定义逻辑，让前端显示的数据与后端获取的数据建立一定的对应关系。
比如Person对象有一个年龄（Age）属性，我们在前端显示某个人的年龄时，可以根据不同的年龄，显示不同的背景颜色。这个时候，实际上是根据这个输入的整型数据返回一个不同颜色的画刷。
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>//
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>// 摘要:
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>//<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> Provides a way to apply custom logic to a binding.
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>public interface IValueConverter
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>object Convert(object value, Type targetType, object parameter, CultureInfo culture);
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture);
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}
IValueConverter接口有两个方法成员，分别是Convert和ConvertBack。
Convert方法成员：输入的value及parameter参数，根据自定义逻辑判断，返回一个object对象给前端XAML使用。
ConvertBack方法成员：与Convert相反，将前端输入的数据转换成另一个对象返回给后端的数据源。
IValueConverter示例
public class AgeToColorConverter : IValueConverter
{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>SolidColorBrush background = Brushes.Black;
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>if (value != null && int.TryParse(value.ToString(), out int age))
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>if (age < 20)
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>background = Brushes.Green;
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>else if (age < 40)
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>background = Brushes.Blue;
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>else if (age < 60)
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>background = Brushes.Orange;
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>else if (age < 80)
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>background = Brushes.Red;
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>else if (age < 90)
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>background = Brushes.Purple;
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>else
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>background = Brushes.Gray;
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>return background;
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>throw new NotImplementedException();
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}
}然后在XAML前端对转换器进行实例化
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>我们就可以使用这个Key名叫AgeToColorConverter的实例。
Background="{Binding Person.Age,Converter={StaticResource AgeToColorConverter}}"
IMultiValueConverter接口
与IValueConverter类似的，还有一个叫IMultiValueConverter——多值转换器。它的定义和IValueConverter也十分类似。
public interface IMultiValueConverter{<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>object Convert(object[] values, Type targetType, object parameter, CultureInfo culture);<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture); }Convert第一个参数变成了values，表示它可以传入多个值。
IMultiValueConverter示例
////// 多值转换器 ///public class MultiColorConverter : IMultiValueConverter {<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> {<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> if (values != null && values.Length == 2)<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> {<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> var age_result = int.TryParse(values.ToString(), out int age);<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> var money_result = int.TryParse(values.ToString(), out int money);<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> if(age_result&& money_result)<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> {<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> if (age < 30 && money > 50000)<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> {<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> return "年纪轻轻的有钱人";<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> }<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> else if (age >= 30 && age = 30 && money > 90000)<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> {<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> return "富豪";<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> }<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> else<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> {<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> return "一个平凡的人";<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> }<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> }<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>}<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> return null;<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> }<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> {<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> throw new NotImplementedException();<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources> } }如上所示，我们定义了一个多值转换器，values参数传入了两个元素，分别是年龄和金钱。这里为什么能确定是两个元素？因为我们在前端使用这个转换器时，明确的传入了两个值。
xaml前端页面使用：
<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>这里需要着重的讲解一下多值转换器在前端的使用。MultiBinding和IMultiValueConverter通常是配套使用的。MultiBinding表示多路绑定的意思，和Binding的用法类似，只是多了一个Bindings集合——表示拥有多个绑定源。
验证规则
ValidationRule是一个抽象类，提供创建自定义规则的一个方式，旨在检查用户输入的有效性。所以，我们要验证前端输入的各项数据的有效性时，需要自己定义各自的验证规则。
在数据绑定时，Binding类有一个ValidationRules属性，这个属性专门用来存放开发者自定义的验证规则。
例如，我们假定用户名的长度必须在1-10个字符之间，且用户的年龄在1-100之前，那么就可以围绕这两个条件自定义两个不同的验证规则，它们定义如下：
用户名验证规则：
public class NameValidationRule : ValidationRule{<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>public override ValidationResult Validate(object value, CultureInfo cultureInfo)<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>{<Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources><Window.Resources>
<local:AgeToColorConverter x:Key="AgeToColorConverter"/>
</Window.Resources>if (value != null && value.ToString().Length > 1 && value.ToString().Length = 1 && myValue
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