限制TextBox输入，只能输入整数

    public class TextBoxInt : TextBox
    {
        public TextBoxInt()
        {
            KeyDown += TextBoxInt_KeyDown;
            TextChanged += TextBoxInt_TextChanged;
        }

        private void TextBoxInt_TextChanged(object sender, TextChangedEventArgs e)
        {
            //屏蔽非法字符粘贴
            var textBox = sender as TextBox;
            if (textBox != null)
            {
                var change = new TextChange[e.Changes.Count];
                e.Changes.CopyTo(change, 0);

                int offset = change[0].Offset;
                if (change[0].AddedLength > 0)
                {
                    int num;
                    if (!int.TryParse(textBox.Text, out num))
                    {
                        textBox.Text = textBox.Text.Remove(offset, change[0].AddedLength);
                        textBox.Select(offset, 0);
                    }
                }
            }
        }

        private void TextBoxInt_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.Key >= Key.NumPad0 && e.Key <= Key.NumPad9)
            {
                // 允许输入数字小键盘上的数字0-9
                e.Handled = false;
            }
            else if ((e.Key >= Key.D0 && e.Key <= Key.D9) && e.KeyboardDevice.Modifiers != ModifierKeys.Shift)
            {
                // 允许输入数字0-9，并且不能同时按着Shift键
                e.Handled = false;
            }
            else if (e.Key == Key.Enter)
            {
                // 允许输入回车
                e.Handled = false;
            }
            else
            {
                e.Handled = true;
            }
        }
    }