WPF设置文本框(TextBox)只能输入数字

<TextBox 
         Width="100" 
         Height="30" 
         PreviewTextInput="TextBox_PreviewTextInput"  
         PreviewKeyDown="TextBox_PreviewKeyDown" 
         InputMethod.IsInputMethodEnabled="False"
         />

private void TextBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
    short val;
    if (!Int16.TryParse(e.Text, out val))
        e.Handled = true;
}

private void TextBox_PreviewKeyDown(object sender, KeyEventArgs e)
{
    if (e.Key == Key.Space)
        e.Handled = true;
}