说明：本文出处：

前台：

<TextBox Name="tb1" Text="{Binding Name,Mode=TwoWay,ValidatesOnExceptions=True}" Height="100" Width="100"/>

后台：

 

Person p = new Person();public MainPage(){    InitializeComponent();    p.Name = "123";    tb1.DataContext = p;}public class Person : INotifyPropertyChanged{    private string name;    public string Name    {        get { return name; }        set        {            if (value.Length > 3)            {                throw new Exception("不能超过三个字!");            }            name = value;            NotifyChange("Name");        }    }    public event PropertyChangedEventHandler PropertyChanged;    private void NotifyChange(string propertyName)    {        if (PropertyChanged != null)        {            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));        }    }}

　　

2.验证TextBox内容不超过指定长度，不失去焦点验证。只需要在上例的基础上为TextBox添加TextChanged事件，并且在事件里通知数据源即可。

private void tb1_TextChanged(object sender, TextChangedEventArgs e)

{     System.Windows.Data.BindingExpression expresson = (sender

as TextBox).GetBindingExpression(TextBox.TextProperty);     expresson.UpdateSource(); }

对验证提示，可以进行样式的设置。

前台添加NotifyOnValidationError属性和BindingValidationError事件

<TextBox Name="tb1" Text="{Binding Name,Mode=TwoWay,ValidatesOnExceptions=True,NotifyOnValidationError=True}" Height="100" Width="100" TextChanged="tb1_TextChanged" BindingValidationError="tb1_BindingValidationError"/>

后台实现BindingValidationError事件

 

1 private void tb1_BindingValidationError(object sender, ValidationErrorEventArgs e) 2 { 3     if (e.Action == ValidationErrorEventAction.Added) 4     { 5         (sender as TextBox).Background = new SolidColorBrush(Colors.Red); 6  7     } 8     else if (e.Action == ValidationErrorEventAction.Removed) 9     {10         (sender as TextBox).Background = new SolidColorBrush(Colors.White);11     }12 13 }

3.标注的方式验证。要添加System.ComponentModel.DataAnnotations.dll引用，并且将数据源的类定义修成为如下形式：

1 public class Person : INotifyPropertyChanged 2 { 3     private string name; 4     [StringLength(3, ErrorMessage = "不能超过3个字,这是标注的方式验证！")] 5     public string Name 6     { 7         get { return name; } 8         set 9         {10             Validator.ValidateProperty(value, new ValidationContext(this, null, null) { MemberName = "Name" });11             name = value;12             NotifyChange("Name");13         }14     }15     public event PropertyChangedEventHandler PropertyChanged;16     private void NotifyChange(string propertyName)17     {18         if (PropertyChanged != null)19         {20             PropertyChanged(this, new PropertyChangedEventArgs(propertyName));21         }22     }23 24 }