WPF中PasswordBox控件无法绑定Password属性解决办法

在WPF中，默认的Password控件的Password属性是不允许为之绑定的，下面是一个解决绑定Password的方法的代码：

1.前台代码

<Window x:Class="PasswordBoxDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="142" Width="256"
        xmlns:Helper="clr-namespace:PasswordBoxDemo"
        WindowStartupLocation="CenterScreen">
    <Grid>
        <ListView x:Name="lvUsers"
                  HorizontalAlignment="Stretch"
                  VerticalAlignment="Stretch"
                  >
            <ListView.View >
                <GridView x:Name="GridView">
                    <GridView.Columns>
                        <GridViewColumn Header="用户名" >
                            <GridViewColumn.CellTemplate>
                                <DataTemplate  >
                                    <TextBox 
                                             HorizontalAlignment="Stretch"
                                             VerticalAlignment="Stretch"
                                             Text="{Binding Path=UserName}"
                                             ToolTip="{Binding Path=UserName}"
                                             Width="100"
                                             Height="20"></TextBox>
                                </DataTemplate>
                            </GridViewColumn.CellTemplate>
                        </GridViewColumn>
                        <GridViewColumn Header="密码" >
                            <GridViewColumn.CellTemplate>
                                <DataTemplate  >
                                    <PasswordBox 
                                                 HorizontalAlignment="Stretch"
                                                 VerticalAlignment="Stretch"
                                                 Width="100"
                                                 Height="20"
                                                 PasswordChar="*"
                                                 MaxLength="20"
                                                 Helper:PasswordBoxHelper.Attach="True"
                                                 Helper:PasswordBoxHelper.Password="{Binding Path=Pwd,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" />
                                </DataTemplate>
                            </GridViewColumn.CellTemplate>
                        </GridViewColumn>
                    </GridView.Columns>
                </GridView>
            </ListView.View>
        </ListView>

    </Grid>
</Window>

2.后台代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Collections.ObjectModel;

namespace PasswordBoxDemo
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            this.Loaded += new RoutedEventHandler(MainWindow_Loaded);
        }

        void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            ObservableCollection<User> users = new ObservableCollection<User>();

            User p = new User();
            p.UserName = "张三";
            p.Pwd = "zhangsan";

            User p2 = new User();
            p2.UserName = "李四";
            p2.Pwd = "lisi";

            users.Add(p);
            users.Add(p2);

            this.lvUsers.ItemsSource = users;
            
        }
    }

    public class User
    {
        private string _userName;
        private string _password;
        public string UserName
        {
            set { _userName = value; }
            get { return _userName; }
        }

        public string Pwd
        {
            set { _password = value; }
            get { return _password; }
        }
    }
}

3. 为PasswordBox控件的Password增加绑定功能 的PasswordBoxHelpe.csr文件

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;

namespace PasswordBoxDemo
{
    /// <summary>  
    /// 为PasswordBox控件的Password增加绑定功能  
    /// </summary>  
    public static class PasswordBoxHelper
    {
        public static readonly DependencyProperty PasswordProperty =
            DependencyProperty.RegisterAttached("Password",
            typeof(string), typeof(PasswordBoxHelper),
            new FrameworkPropertyMetadata(string.Empty, OnPasswordPropertyChanged));
        public static readonly DependencyProperty AttachProperty =
            DependencyProperty.RegisterAttached("Attach",
            typeof(bool), typeof(PasswordBoxHelper), new PropertyMetadata(false, Attach));
        private static readonly DependencyProperty IsUpdatingProperty =
           DependencyProperty.RegisterAttached("IsUpdating", typeof(bool),
           typeof(PasswordBoxHelper));

        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);
        }
    }
}