【WPF】验证

 <Window.Resources>
        <!--数据源-->
        <local:Person Age="100" Name="Tom" x:Key="Data"></local:Person>
        <!--TextBox模板-->
        <Style  TargetType="{x:Type TextBox}">
            <Style.Triggers>
                <!--验证触发-->
                <Trigger Property="Validation.HasError" Value="True">
                    <!--错误信息模板-->
                    <Setter Property="Validation.ErrorTemplate">
                        <Setter.Value>
                            <ControlTemplate>
                                <DockPanel LastChildFill="True">
                                    <Border Background="Red" DockPanel.Dock="Right" Margin="5,0,0,0"
                                            Width="20" Height="20" CornerRadius="20"
                                            ToolTip="{Binding ElementName=customAdorner,Path=AdornedElement.(Validation.Errors)[0].ErrorContent}">
                                        <TextBlock Text="*" VerticalAlignment="Center" HorizontalAlignment="Center"
                                                   FontWeight="Bold" Foreground="White"/>
                                    </Border>
                                    <!--占位，表示修饰控件相对于ControlTemplate中其它元素所放置的位置（这个示例中用于文本框的占位）-->
                                    <AdornedElementPlaceholder Name="customAdorner" VerticalAlignment="Center">
                                        <Border BorderBrush="Red" BorderThickness="1"></Border>
                                    </AdornedElementPlaceholder>
                                </DockPanel>
                              
                            </ControlTemplate>
                        </Setter.Value>
                    </Setter>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <Grid>
        <TextBox Height="35" Width="120"
                 Text="{Binding Source={StaticResource Data},Path=Age,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged,
            ValidatesOnDataErrors=True,ValidatesOnExceptions=True,
            NotifyOnValidationError=True}" />
    </Grid>

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;

namespace WpfCommand.Models
{
    public class Person:INotifyPropertyChanged,IDataErrorInfo
    {

        private string _name;
        public string Name
        {
            get { return _name; }
            set {
                _name = value;
                RaisePropertyChanged("Name");
            }
        }
     private int _age;
       // [Range]  ValidationAttribute：（需要添加 System.ComponentModel.DataAnnotations.dll）
        
       [Range(19,99,ErrorMessage="未成年")]

        public int Age
        {
            get { return _age; }
            set {
                _age = value;
                RaisePropertyChanged("Age");
            }
        }

        public string Error { get { return ""; } }

        //索引器
        public string this[string ColumnName]
        {
            get {
                var vc = new ValidationContext(this, null, null);
                vc.MemberName = ColumnName;
                var res = new List<ValidationResult>();
                var result = Validator.TryValidateProperty(this.GetType().GetProperty(ColumnName).GetValue(this, null), vc, res);
                if (res.Count > 0)
                { 
                    return string.Join(Environment.NewLine,res.Select(r=>r.ErrorMessage).ToArray());
                }
                return string.Empty;
            }
            
        }

        public event PropertyChangedEventHandler PropertyChanged;

        public virtual void RaisePropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
            
        }
    }
}