这是一种改进的WilPs解答。 我的改进是:

改进了删除和退格键的行为 增加了EmptyValue属性，如果空字符串是不合适的 修正了一些小错别字

/// <summary>
///     Regular expression for Textbox with properties: 
///         <see cref="RegularExpression"/>, 
///         <see cref="MaxLength"/>,
///         <see cref="EmptyValue"/>.
/// </summary>
public class TextBoxInputRegExBehaviour : Behavior<TextBox>
{
    #region DependencyProperties
    public static readonly DependencyProperty RegularExpressionProperty =
        DependencyProperty.Register("RegularExpression", typeof(string), typeof(TextBoxInputRegExBehaviour), new FrameworkPropertyMetadata(".*"));

    public string RegularExpression
    {
        get { return (string)GetValue(RegularExpressionProperty); }
        set { SetValue(RegularExpressionProperty, value); }
    }

    public static readonly DependencyProperty MaxLengthProperty =
        DependencyProperty.Register("MaxLength", typeof(int), typeof(TextBoxInputRegExBehaviour),
                                        new FrameworkPropertyMetadata(int.MinValue));

    public int MaxLength
    {
        get { return (int)GetValue(MaxLengthProperty); }
        set { SetValue(MaxLengthProperty, value); }
    }

    public static readonly DependencyProperty EmptyValueProperty =
        DependencyProperty.Register("EmptyValue", typeof(string), typeof(TextBoxInputRegExBehaviour), null);

    public string EmptyValue
    {
        get { return (string)GetValue(EmptyValueProperty); }
        set { SetValue(EmptyValueProperty, value); }
    }
    #endregion

    /// <summary>
    ///     Attach our behaviour. Add event handlers
    /// </summary>
    protected override void OnAttached()
    {
        base.OnAttached();

        AssociatedObject.PreviewTextInput += PreviewTextInputHandler;
        AssociatedObject.PreviewKeyDown += PreviewKeyDownHandler;
        DataObject.AddPastingHandler(AssociatedObject, PastingHandler);
    }

    /// <summary>
    ///     Deattach our behaviour. remove event handlers
    /// </summary>
    protected override void OnDetaching()
    {
        base.OnDetaching();

        AssociatedObject.PreviewTextInput -= PreviewTextInputHandler;
        AssociatedObject.PreviewKeyDown -= PreviewKeyDownHandler;
        DataObject.RemovePastingHandler(AssociatedObject, PastingHandler);
    }

    #region Event handlers [PRIVATE] --------------------------------------

    void PreviewTextInputHandler(object sender, TextCompositionEventArgs e)
    {
        string text;
        if (this.AssociatedObject.Text.Length < this.AssociatedObject.CaretIndex)
            text = this.AssociatedObject.Text;
        else
        {
            //  Remaining text after removing selected text.
            string remainingTextAfterRemoveSelection;

            text = TreatSelectedText(out remainingTextAfterRemoveSelection)
                ? remainingTextAfterRemoveSelection.Insert(AssociatedObject.SelectionStart, e.Text)
                : AssociatedObject.Text.Insert(this.AssociatedObject.CaretIndex, e.Text);
        }

        e.Handled = !ValidateText(text);
    }

    /// <summary>
    ///     PreviewKeyDown event handler
    /// </summary>
    void PreviewKeyDownHandler(object sender, KeyEventArgs e)
    {
        if (string.IsNullOrEmpty(this.EmptyValue))
            return;

        string text = null;

        // Handle the Backspace key
        if (e.Key == Key.Back)
        {
            if (!this.TreatSelectedText(out text))
            {
                if (AssociatedObject.SelectionStart > 0)
                    text = this.AssociatedObject.Text.Remove(AssociatedObject.SelectionStart - 1, 1);
            }
        }
        // Handle the Delete key
        else if (e.Key == Key.Delete)
        {
            // If text was selected, delete it
            if (!this.TreatSelectedText(out text) && this.AssociatedObject.Text.Length > AssociatedObject.SelectionStart)
            {
                // Otherwise delete next symbol
                text = this.AssociatedObject.Text.Remove(AssociatedObject.SelectionStart, 1);
            }
        }

        if (text == string.Empty)
        {
            this.AssociatedObject.Text = this.EmptyValue;
            if (e.Key == Key.Back)
                AssociatedObject.SelectionStart++;
            e.Handled = true;
        }
    }

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

            if (!ValidateText(text))
                e.CancelCommand();
        }
        else
            e.CancelCommand();
    }
    #endregion Event handlers [PRIVATE] -----------------------------------

    #region Auxiliary methods [PRIVATE] -----------------------------------

    /// <summary>
    ///     Validate certain text by our regular expression and text length conditions
    /// </summary>
    /// <param name="text"> Text for validation </param>
    /// <returns> True - valid, False - invalid </returns>
    private bool ValidateText(string text)
    {
        return (new Regex(this.RegularExpression, RegexOptions.IgnoreCase)).IsMatch(text) && (MaxLength == int.MinValue || text.Length <= MaxLength);
    }

    /// <summary>
    ///     Handle text selection
    /// </summary>
    /// <returns>true if the character was successfully removed; otherwise, false. </returns>
    private bool TreatSelectedText(out string text)
    {
        text = null;
        if (AssociatedObject.SelectionLength <= 0) 
            return false;

        var length = this.AssociatedObject.Text.Length;
        if (AssociatedObject.SelectionStart >= length)
            return true;

        if (AssociatedObject.SelectionStart + AssociatedObject.SelectionLength >= length)
            AssociatedObject.SelectionLength = length - AssociatedObject.SelectionStart;

        text = this.AssociatedObject.Text.Remove(AssociatedObject.SelectionStart, AssociatedObject.SelectionLength);
        return true;
    }
    #endregion Auxiliary methods [PRIVATE] --------------------------------
}

用法非常简单:

<i:Interaction.Behaviors>
    <behaviours:TextBoxInputRegExBehaviour RegularExpression="^\d+$" MaxLength="9" EmptyValue="0" />
</i:Interaction.Behaviors>

受雷的启发，我有一个简单的解决方案。这应该足以识别任何形式的数字。

如果您只想要正数、整数值或精确到小数点后最大位数的值，则可以轻松修改此解决方案。

正如Ray的回答所建议的，你需要首先添加一个PreviewTextInput事件:

<TextBox PreviewTextInput="TextBox_OnPreviewTextInput"/>

然后把下面的代码放在后面:

private void TextBox_OnPreviewTextInput(object sender, TextCompositionEventArgs e)
{
    var textBox = sender as TextBox;
    // Use SelectionStart property to find the caret position.
    // Insert the previewed text into the existing text in the textbox.
    var fullText = textBox.Text.Insert(textBox.SelectionStart, e.Text);

    double val;
    // If parsing is successful, set Handled to false
    e.Handled = !double.TryParse(fullText, out val);
}

对于无效的空格，我们可以添加NumberStyles:

using System.Globalization;

private void TextBox_OnPreviewTextInput(object sender, TextCompositionEventArgs e)
{
    var textBox = sender as TextBox;
    // Use SelectionStart property to find the caret position.
    // Insert the previewed text into the existing text in the textbox.
    var fullText = textBox.Text.Insert(textBox.SelectionStart, e.Text);

    double val;
    // If parsing is successful, set Handled to false
    e.Handled = !double.TryParse(fullText, 
                                 NumberStyles.AllowDecimalPoint | NumberStyles.AllowLeadingSign, 
                                 CultureInfo.InvariantCulture,
                                 out val);
}

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();
    }
}

扩展的WPF工具包有一个:NumericUpDown

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

这是唯一需要的代码:

void MyTextBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
    e.Handled = new Regex("[^0-9]+").IsMatch(e.Text);
}

这只允许在文本框中输入数字。

若要允许使用小数点或负号，可以将正则表达式更改为[^0-9.-]+。