private void TextBox_PreviewKeyDown(object sender, KeyEventArgs e)

        {

            TextBox txt = sender as TextBox;

            if (txt.Text.Length <= 10) //控制字符长度

            {

                //屏蔽非法按键

                if ((e.Key >= Key.NumPad0 && e.Key <= Key.NumPad9) || e.Key == Key.Decimal || e.Key.ToString() == "Tab")

                {

                    if (txt.Text.Contains(".") && e.Key == Key.Decimal)

                    {

                        e.Handled = true;

                        return;

                    }

                    e.Handled = false;

                }

                else if (((e.Key >= Key.D0 && e.Key <= Key.D9) || e.Key == Key.OemPeriod || e.Key == Key.Back || e.Key == Key.Delete) && e.KeyboardDevice.Modifiers != ModifierKeys.Shift)

                {

                    if (txt.Text.Contains(".") && e.Key == Key.OemPeriod)

                    {

                        e.Handled = true;

                        return;

                    }

                    e.Handled = false;

                }

                else if (e.Key == Key.Enter)

                {

                    TraversalRequest request = new TraversalRequest(FocusNavigationDirection.Next);// MoveFocus takes a TraveralReqest as its argument.

                    UIElement elementWithFocus = Keyboard.FocusedElement as UIElement;// Gets the element with keyboard focus.

                    if (elementWithFocus != null)

                    {

                        elementWithFocus.MoveFocus(request);// Change keyboard focus.

                    }

                    e.Handled = true;

                }

                else

                {

                    e.Handled = true;

                }

            }

            else if (e.Key == Key.Back)

            {

                e.Handled = false;

            }

            else

            {

                e.Handled = true;

            }

        }

 

 

 

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