在Windows窗体中，这很容易;你可以添加一个事件按键和一切工作轻松。然而，在WPF中该事件不存在。但是有一个更简单的方法。

WPF文本框有TextChanged事件，这是一般的一切。它包括粘贴，输入和任何你能想到的东西。

所以你可以这样做:

XAML:

<TextBox name="txtBox1" ... TextChanged="TextBox_TextChanged"/>

背后的代码:

private void TextBox_TextChanged(object sender, TextChangedEventArgs e) {
    string s = Regex.Replace(((TextBox)sender).Text, @"[^\d.]", "");
    ((TextBox)sender).Text = s;
}

这也是可以接受的。，如果你不想要它，只需将它从正则表达式语句中删除为@[^\d]。

注意:此事件可以用于许多TextBox元素，因为它使用发送方对象的文本。您只需编写一次事件，并且可以将其用于多个TextBox元素。

我们可以对文本框更改事件进行验证。下面的实现可以防止除数字和一个小数点以外的按键输入。

private void textBoxNumeric_TextChanged(object sender, TextChangedEventArgs e) 
{         
      TextBox textBox = sender as TextBox;         
      Int32 selectionStart = textBox.SelectionStart;         
      Int32 selectionLength = textBox.SelectionLength;         
      String newText = String.Empty;         
      int count = 0;         
      foreach (Char c in textBox.Text.ToCharArray())         
      {             
         if (Char.IsDigit(c) || Char.IsControl(c) || (c == '.' && count == 0))             
         {                 
            newText += c;                 
            if (c == '.')                     
              count += 1;             
         }         
     }         
     textBox.Text = newText;         
     textBox.SelectionStart = selectionStart <= textBox.Text.Length ? selectionStart :        textBox.Text.Length;     
} 

添加预览文本输入事件。像这样:<TextBox PreviewTextInput="PreviewTextInput" />。

然后在这个set中，如果文本不被允许，e。handled。e.Handled = ! istextallows (e.Text);

我在istextalered方法中使用一个简单的正则表达式来查看我是否应该允许他们键入的内容。在我的例子中，我只允许数字、点和破折号。

private static readonly Regex _regex = new Regex("[^0-9.-]+"); //regex that matches disallowed text
private static bool IsTextAllowed(string text)
{
    return !_regex.IsMatch(text);
}

如果您希望防止粘贴不正确的数据，请连接数据对象。粘贴事件数据对象。粘贴="TextBoxPasting"如下所示(代码摘录):

// Use the DataObject.Pasting Handler 
private void TextBoxPasting(object sender, DataObjectPastingEventArgs e)
{
    if (e.DataObject.GetDataPresent(typeof(String)))
    {
        String text = (String)e.DataObject.GetData(typeof(String));
        if (!IsTextAllowed(text))
        {
            e.CancelCommand();
        }
    }
    else
    {
        e.CancelCommand();
    }
}

我使用了一些已经在这里的东西，并使用一个行为把我自己的扭曲，这样我就不必在大量的视图中传播这段代码……

public class AllowableCharactersTextBoxBehavior : Behavior<TextBox>
{
    public static readonly DependencyProperty RegularExpressionProperty =
         DependencyProperty.Register("RegularExpression", typeof(string), typeof(AllowableCharactersTextBoxBehavior),
         new FrameworkPropertyMetadata(".*"));
    public string RegularExpression
    {
        get
        {
            return (string)base.GetValue(RegularExpressionProperty);
        }
        set
        {
            base.SetValue(RegularExpressionProperty, value);
        }
    }

    public static readonly DependencyProperty MaxLengthProperty =
        DependencyProperty.Register("MaxLength", typeof(int), typeof(AllowableCharactersTextBoxBehavior),
        new FrameworkPropertyMetadata(int.MinValue));
    public int MaxLength
    {
        get
        {
            return (int)base.GetValue(MaxLengthProperty);
        }
        set
        {
            base.SetValue(MaxLengthProperty, value);
        }
    }

    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.PreviewTextInput += OnPreviewTextInput;
        DataObject.AddPastingHandler(AssociatedObject, OnPaste);
    }

    private void OnPaste(object sender, DataObjectPastingEventArgs e)
    {
        if (e.DataObject.GetDataPresent(DataFormats.Text))
        {
            string text = Convert.ToString(e.DataObject.GetData(DataFormats.Text));

            if (!IsValid(text, true))
            {
                e.CancelCommand();
            }
        }
        else
        {
            e.CancelCommand();
        }
    }

    void OnPreviewTextInput(object sender, System.Windows.Input.TextCompositionEventArgs e)
    {
        e.Handled = !IsValid(e.Text, false);
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        AssociatedObject.PreviewTextInput -= OnPreviewTextInput;
        DataObject.RemovePastingHandler(AssociatedObject, OnPaste);
    }

    private bool IsValid(string newText, bool paste)
    {
        return !ExceedsMaxLength(newText, paste) && Regex.IsMatch(newText, RegularExpression);
    }

    private bool ExceedsMaxLength(string newText, bool paste)
    {
        if (MaxLength == 0) return false;

        return LengthOfModifiedText(newText, paste) > MaxLength;
    }

    private int LengthOfModifiedText(string newText, bool paste)
    {
        var countOfSelectedChars = this.AssociatedObject.SelectedText.Length;
        var caretIndex = this.AssociatedObject.CaretIndex;
        string text = this.AssociatedObject.Text;

        if (countOfSelectedChars > 0 || paste)
        {
            text = text.Remove(caretIndex, countOfSelectedChars);
            return text.Length + newText.Length;
        }
        else
        {
            var insert = Keyboard.IsKeyToggled(Key.Insert);

            return insert && caretIndex < text.Length ? text.Length : text.Length + newText.Length;
        }
    }
}

下面是相关的视图代码:

<TextBox MaxLength="50" TextWrapping="Wrap" MaxWidth="150" Margin="4"
 Text="{Binding Path=FileNameToPublish}" >
     <interactivity:Interaction.Behaviors>
         <v:AllowableCharactersTextBoxBehavior RegularExpression="^[0-9.\-]+$" MaxLength="50" />
     </interactivity:Interaction.Behaviors>
</TextBox>

Use:

Private Sub DetailTextBox_PreviewTextInput( _
  ByVal sender As Object, _
  ByVal e As System.Windows.Input.TextCompositionEventArgs) _
  Handles DetailTextBox.PreviewTextInput

    If _IsANumber Then
        If Not Char.IsNumber(e.Text) Then
            e.Handled = True
        End If
    End If
End Sub

在WPF应用程序中，你可以通过处理TextChanged事件来处理这个:

void arsDigitTextBox_TextChanged(object sender, System.Windows.Controls.TextChangedEventArgs e)
{
    Regex regex = new Regex("[^0-9]+");
    bool handle = regex.IsMatch(this.Text);
    if (handle)
    {
        StringBuilder dd = new StringBuilder();
        int i = -1;
        int cursor = -1;
        foreach (char item in this.Text)
        {
            i++;
            if (char.IsDigit(item))
                dd.Append(item);
            else if(cursor == -1)
                cursor = i;
        }
        this.Text = dd.ToString();

        if (i == -1)
            this.SelectionStart = this.Text.Length;
        else
            this.SelectionStart = cursor;
    }
}