WPFPasswordBoxMVVM实现

由于PasswordBox.Password属性非依赖属性，所以不能作为绑定的目标，以下是本人的MVVM实现方法。

PasswordBox.Password与TextBox.Text同步，TextBox只是为了演示，实际使用的是TextBox.Text绑定的Source。

通过Behavior添加PasswordChanged事件的事件处理器，以及自定义一个附加属性实现绑定，Behavior需要引用System.Windows.Interactivity.dll，代码如下：

using System.Windows;
using System.Windows.Controls;
using System.Windows.Interactivity;
namespace PasswordHelperTest
{
public static class PasswordBoxHelper
{
public static readonly DependencyProperty PasswordProperty =
DependencyProperty.RegisterAttached("Password",
typeof(string), typeof(PasswordBoxHelper),
new FrameworkPropertyMetadata(string.Empty, OnPasswordPropertyChanged));
private static void OnPasswordPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
PasswordBox passwordBox = sender as PasswordBox;
string password = (string)e.NewValue;
if (passwordBox != null && passwordBox.Password != password)
{
passwordBox.Password = password;
}
}
public static string GetPassword(DependencyObject dp)
{
return (string)dp.GetValue(PasswordProperty);
}
public static void SetPassword(DependencyObject dp, string value)
{
dp.SetValue(PasswordProperty, value);
}
}
public class PasswordBoxBehavior : Behavior

{
protected override void OnAttached()
{
base.OnAttached();
AssociatedObject.PasswordChanged += OnPasswordChanged;
}
private static void OnPasswordChanged(object sender, RoutedEventArgs e)
{
PasswordBox passwordBox = sender as PasswordBox;
string password = PasswordBoxHelper.GetPassword(passwordBox);
if (passwordBox != null && passwordBox.Password != password)
{
PasswordBoxHelper.SetPassword(passwordBox, passwordBox.Password);
}
}
protected override void OnDetaching()
{
base.OnDetaching();
AssociatedObject.PasswordChanged -= OnPasswordChanged;
}
}
}

View代码如下：

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:local="clr-namespace:PasswordHelperTest"
Title="MainWindow" >

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
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;
namespace PasswordHelperTest
{
///

ViewModel引用Microsoft.Practices.Prism.dll，代码如下：

using Microsoft.Practices.Prism.ViewModel;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace PasswordHelperTest
{
class MainWindowViewModel : NotificationObject
{
private string _password;
public string Password
{
get { return _password; }
set
{
if (_password != value)
{
_password = value;
this.RaisePropertyChanged("Password");
}
}
}
}
}