mvvmlight下passwordBox绑定的解决方法

在做公司的项目中，用到MVVMLight框架，需要做登陆注册的功能模块，但是在wpf中passwordBox没有内置绑定功能，因为出于安全的考虑。但是，博主又非常想要契合mvvm思想，一定要passwordBox在View绑定到ViewModel，经过网上查找，以及多次实验，终于成功。特此记录。

(开发环境：vs2015+EF+mvvmlight+sql server2016)

首先建一个Helper类：

    public class PasswordBindingHelper

    {

        public static readonly DependencyProperty PasswordProperty =

        DependencyProperty.RegisterAttached("Password",

        typeof(string), typeof(PasswordBindingHelper),

        new FrameworkPropertyMetadata(string.Empty, OnPasswordPropertyChanged));

        public static readonly DependencyProperty AttachProperty =

            DependencyProperty.RegisterAttached("Attach",

            typeof(bool), typeof(PasswordBindingHelper), new PropertyMetadata(false, Attach));

        private static readonly DependencyProperty IsUpdatingProperty =

           DependencyProperty.RegisterAttached("IsUpdating", typeof(bool),

           typeof(PasswordBindingHelper));

        public static void SetAttach(DependencyObject dp, bool value)

        {

            dp.SetValue(AttachProperty, value);

        }

        public static bool GetAttach(DependencyObject dp)

        {

            return (bool)dp.GetValue(AttachProperty);

        }

        public static string GetPassword(DependencyObject dp)

        {

            return (string)dp.GetValue(PasswordProperty);

        }

        public static void SetPassword(DependencyObject dp, string value)

        {

            dp.SetValue(PasswordProperty, value);

        }

        private static bool GetIsUpdating(DependencyObject dp)

        {

            return (bool)dp.GetValue(IsUpdatingProperty);

        }

        private static void SetIsUpdating(DependencyObject dp, bool value)

        {

            dp.SetValue(IsUpdatingProperty, value);

        }

        private static void OnPasswordPropertyChanged(DependencyObject sender,

            DependencyPropertyChangedEventArgs e)

        {

            PasswordBox passwordBox = sender as PasswordBox;

            passwordBox.PasswordChanged -= PasswordChanged;

            if (!(bool)GetIsUpdating(passwordBox))

            {

                passwordBox.Password = (string)e.NewValue;

            }

            passwordBox.PasswordChanged += PasswordChanged;

        }

        private static void Attach(DependencyObject sender,

            DependencyPropertyChangedEventArgs e)

        {

            PasswordBox passwordBox = sender as PasswordBox;

            if (passwordBox == null)

                return;

            if ((bool)e.OldValue)

            {

                passwordBox.PasswordChanged -= PasswordChanged;

            }

            if ((bool)e.NewValue)

            {

                passwordBox.PasswordChanged += PasswordChanged;

            }

        }

        private static void PasswordChanged(object sender, RoutedEventArgs e)

        {

            PasswordBox passwordBox = sender as PasswordBox;

            SetIsUpdating(passwordBox, true);

            SetPassword(passwordBox, passwordBox.Password);

            SetIsUpdating(passwordBox, false);

        }

    }

View：

<Page x:Class="SGGS.SmartGroundGuidence.Pages.LoginPage"

      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

      xmlns:local="clr-namespace:SGGS.SmartGroundGuidence.Pages"

      xmlns:helper="clr-namespace:SGGS.SmartGroundGuidence.CommonHelper"

      mc:Ignorable="d"

      Title="LoginPage">

    <Page.DataContext>

        <Binding Path="LoginPage" Source="{StaticResource Locator}"></Binding>

    </Page.DataContext>

    <Grid VerticalAlignment="Top" Width="512" Height="417">

        <Grid.Background>

            <ImageBrush ImageSource="Resources/bg_login_popup.png" />

        </Grid.Background>

        <Grid.RowDefinitions>

            <RowDefinition Height="60"></RowDefinition>

            <RowDefinition Height="58"></RowDefinition>

            <RowDefinition Height="20"></RowDefinition>

            <RowDefinition Height="58"></RowDefinition>

            <RowDefinition Height="25"></RowDefinition>

            <RowDefinition Height="29"></RowDefinition>

            <RowDefinition Height="60"></RowDefinition>

            <RowDefinition Height="57"></RowDefinition>

            <RowDefinition Height="52"></RowDefinition>

        </Grid.RowDefinitions>

        <StackPanel Grid.Row="1">

            <Grid Height="58" Width="404">

                <Grid.ColumnDefinitions>

                    <ColumnDefinition Width="115*"></ColumnDefinition>

                    <ColumnDefinition Width="289*"></ColumnDefinition>

                </Grid.ColumnDefinitions>

                <TextBox  Grid.Column="0" Grid.ColumnSpan="2" Style="{StaticResource SltTxtLogin}" Text="{Binding LoginUser.UserName,UpdateSourceTrigger=PropertyChanged}"/>

                <Label Grid.Column="0" FontSize="18" Foreground="White" Content="用户名" VerticalAlignment="Center" HorizontalAlignment="Center"/>

            </Grid>

        </StackPanel>

        <StackPanel Grid.Row="3">

            <Grid Height="58" Width="404">

                <Grid.ColumnDefinitions>

                    <ColumnDefinition Width="115*"></ColumnDefinition>

                    <ColumnDefinition Width="289*"></ColumnDefinition>

                </Grid.ColumnDefinitions>

                <PasswordBox Grid.Column="0" Grid.ColumnSpan="2" Style="{StaticResource SltPwbLogin}" MaxLength="20" helper:PasswordBindingHelper.Password="{Binding Password,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/>

                <Label Grid.Column="0" FontSize="18" Foreground="White" Content="密码" VerticalAlignment="Center" HorizontalAlignment="Center"/>

            </Grid>

        </StackPanel>

        <StackPanel Grid.Row="5">

            <Grid Width="404">

                <CheckBox Style="{StaticResource MyCheckBoxStyle}" HorizontalAlignment="Left" Margin="15,0,0,0" IsChecked="{x:Null}"></CheckBox>

            </Grid>

        </StackPanel>

        <StackPanel Grid.Row="7" Orientation="Horizontal" HorizontalAlignment="Center">

            <Button Style="{StaticResource StlBtnLogin}" />

            <Button Style="{StaticResource StlBtnRegister}" Margin="72,0,0,0"/>

        </StackPanel>

    </Grid>

</Page>

剩下的Model和ViewModel以及ViewModelLocator就是MVVMLight的事了，和本文无关，记录到此。

巴特西

mvvmlight下passwordBox绑定的解决方法

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