WPF中将password非依赖属性转化为依赖属性

1封装一个PasswordBoxBindingHelper

public static class PasswordBoxBindingHelper
    {
        public static bool GetIsPasswordBindingEnabled(DependencyObject obj)
        {
            return (bool)obj.GetValue(IsPasswordBindingEnabledProperty);
        }

        public static void SetIsPasswordBindingEnabled(DependencyObject obj, bool value)
        {
            obj.SetValue(IsPasswordBindingEnabledProperty, value);
        }

        public static readonly DependencyProperty IsPasswordBindingEnabledProperty =
            DependencyProperty.RegisterAttached("IsPasswordBindingEnabled", typeof(bool),
            typeof(PasswordBoxBindingHelper),
            new UIPropertyMetadata(false, OnIsPasswordBindingEnabledChanged));

        private static void OnIsPasswordBindingEnabledChanged(DependencyObject obj,DependencyPropertyChangedEventArgs e)
        {
            var passwordBox = obj as PasswordBox;

            if (passwordBox != null)
            {
                passwordBox.PasswordChanged -= PasswordBoxPasswordChanged;

                if ((bool)e.NewValue)
                {
                    passwordBox.PasswordChanged += PasswordBoxPasswordChanged;
                }

            }
        }

        //when the passwordBox's password changed, update the buffer
        static void PasswordBoxPasswordChanged(object sender, RoutedEventArgs e)
        {
            var passwordBox = (PasswordBox)sender;

            if (!String.Equals(GetBindedPassword(passwordBox), passwordBox.Password))
            {
                SetBindedPassword(passwordBox, passwordBox.Password);
            }
        }


        public static string GetBindedPassword(DependencyObject obj)
        {
            return (string)obj.GetValue(BindedPasswordProperty);
        }


        public static void SetBindedPassword(DependencyObject obj, string value)
        {
            obj.SetValue(BindedPasswordProperty, value);
        }

        public static readonly DependencyProperty BindedPasswordProperty =
            DependencyProperty.RegisterAttached("BindedPassword", typeof(string),
            typeof(PasswordBoxBindingHelper),
            new UIPropertyMetadata(string.Empty, OnBindedPasswordChanged));

        //when the buffer changed, upate the passwordBox's password
        private static void OnBindedPasswordChanged(DependencyObject obj,
                                                    DependencyPropertyChangedEventArgs e)
        {
            var passwordBox = obj as PasswordBox;
            if (passwordBox != null)
            {
                passwordBox.Password = e.NewValue == null ? string.Empty : e.NewValue.ToString();
            }
        }

    }

2界面XAML进行属性绑定

<PasswordBox  Helpers:PasswordBoxBindingHelper.IsPasswordBindingEnabled="True"  Grid.Row="4" Grid.Column="1" Height="27" Margin="208,6.6,213.6,6.4"
                     Helpers:PasswordBoxBindingHelper.BindedPassword=
                     "{Binding Path=Password, Mode=TwoWay, UpdateSourceTrigger=LostFocus}" 
                      PasswordChanged="TxtPassword_PasswordChanged"/>