如果你想把它组合在一个控件和一个命令中

<PasswordBox Name="PasswordBoxPin" PasswordChar="*">
    <PasswordBox.InputBindings>
        <KeyBinding Key="Return" Command="{Binding AuthentifyEmpCommand}" CommandParameter="{Binding ElementName=PasswordBoxPin}"/>
    </PasswordBox.InputBindings>
</PasswordBox>

在你的Vm上(就像Konamiman展示的那样)

public void AuthentifyEmp(object obj)
{
    var passwordBox = obj as PasswordBox;
    var password = passwordBox.Password;
}
private RelayCommand _authentifyEmpCommand;
public RelayCommand AuthentifyEmpCommand => _authentifyEmpCommand ?? (_authentifyEmpCommand = new RelayCommand(AuthentifyEmp, null));

编辑:根据评论，我觉得有必要指出这违反了MVVM模式，只有当这不是您主要关注的问题之一时才使用它。

我在这里发布了一个GIST，它是一个可绑定的密码框。

using System.Windows;
using System.Windows.Controls;

namespace CustomControl
{
    public class BindablePasswordBox : Decorator
    {
        /// <summary>
        /// The password dependency property.
        /// </summary>
        public static readonly DependencyProperty PasswordProperty;

        private bool isPreventCallback;
        private RoutedEventHandler savedCallback;

        /// <summary>
        /// Static constructor to initialize the dependency properties.
        /// </summary>
        static BindablePasswordBox()
        {
            PasswordProperty = DependencyProperty.Register(
                "Password",
                typeof(string),
                typeof(BindablePasswordBox),
                new FrameworkPropertyMetadata("", FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, new PropertyChangedCallback(OnPasswordPropertyChanged))
            );
        }

        /// <summary>
        /// Saves the password changed callback and sets the child element to the password box.
        /// </summary>
        public BindablePasswordBox()
        {
            savedCallback = HandlePasswordChanged;

            PasswordBox passwordBox = new PasswordBox();
            passwordBox.PasswordChanged += savedCallback;
            Child = passwordBox;
        }

        /// <summary>
        /// The password dependency property.
        /// </summary>
        public string Password
        {
            get { return GetValue(PasswordProperty) as string; }
            set { SetValue(PasswordProperty, value); }
        }

        /// <summary>
        /// Handles changes to the password dependency property.
        /// </summary>
        /// <param name="d">the dependency object</param>
        /// <param name="eventArgs">the event args</param>
        private static void OnPasswordPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs eventArgs)
        {
            BindablePasswordBox bindablePasswordBox = (BindablePasswordBox) d;
            PasswordBox passwordBox = (PasswordBox) bindablePasswordBox.Child;

            if (bindablePasswordBox.isPreventCallback)
            {
                return;
            }

            passwordBox.PasswordChanged -= bindablePasswordBox.savedCallback;
            passwordBox.Password = (eventArgs.NewValue != null) ? eventArgs.NewValue.ToString() : "";
            passwordBox.PasswordChanged += bindablePasswordBox.savedCallback;
        }

        /// <summary>
        /// Handles the password changed event.
        /// </summary>
        /// <param name="sender">the sender</param>
        /// <param name="eventArgs">the event args</param>
        private void HandlePasswordChanged(object sender, RoutedEventArgs eventArgs)
        {
            PasswordBox passwordBox = (PasswordBox) sender;

            isPreventCallback = true;
            Password = passwordBox.Password;
            isPreventCallback = false;
        }
    }
}

好吧，我的答案更简单，只是在MVVM模式

在类视图模型中

public string password;

PasswordChangedCommand = new DelegateCommand<RoutedEventArgs>(PasswordChanged);

Private void PasswordChanged(RoutedEventArgs obj)

{

    var e = (WatermarkPasswordBox)obj.OriginalSource;

    //or depending or what are you using

    var e = (PasswordBox)obj.OriginalSource;

    password =e.Password;

}

win提供的PasswordBox或XCeedtoolkit提供的WatermarkPasswordBox的password属性生成一个RoutedEventArgs，以便您可以绑定它。

现在在xmal视图中

<Xceed:WatermarkPasswordBox Watermark="Input your Password" Grid.Column="1" Grid.ColumnSpan="3" Grid.Row="7" PasswordChar="*" >

        <i:Interaction.Triggers>

            <i:EventTrigger EventName="PasswordChanged">

                <prism:InvokeCommandAction Command="{Binding RelativeSource={RelativeSource AncestorType=UserControl}, Path= DataContext.PasswordChangedCommand}" CommandParameter="{Binding RelativeSource={RelativeSource Self}, Path= Password}"/>

            </i:EventTrigger>

        </i:Interaction.Triggers>

    </Xceed:WatermarkPasswordBox>

or

<PasswordBox Grid.Column="1" Grid.ColumnSpan="3" Grid.Row="7" PasswordChar="*" >

        <i:Interaction.Triggers>

            <i:EventTrigger EventName="PasswordChanged">

                <prism:InvokeCommandAction Command="{Binding RelativeSource={RelativeSource AncestorType=UserControl}, Path= DataContext.PasswordChangedCommand}" CommandParameter="{Binding RelativeSource={RelativeSource Self}, Path= Password}"/>

            </i:EventTrigger>

        </i:Interaction.Triggers>

    </PasswordBox>

对我来说，这两件事都不对:

实现明文密码属性 将PasswordBox作为命令参数发送给ViewModel

像Steve在CO中描述的那样传输SecurePassword (SecureString实例)似乎是可以接受的。我更喜欢行为而不是背后的代码，而且我还需要能够从视图模型重置密码。

Xaml (Password是ViewModel属性):

<PasswordBox>
    <i:Interaction.Behaviors>
        <behaviors:PasswordBinding BoundPassword="{Binding Password, Mode=TwoWay}" />
    </i:Interaction.Behaviors>
</PasswordBox>

行为:

using System.Security;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Interactivity;

namespace Evidence.OutlookIntegration.AddinLogic.Behaviors
{
    /// <summary>
    /// Intermediate class that handles password box binding (which is not possible directly).
    /// </summary>
    public class PasswordBoxBindingBehavior : Behavior<PasswordBox>
    {
        // BoundPassword
        public SecureString BoundPassword { get { return (SecureString)GetValue(BoundPasswordProperty); } set { SetValue(BoundPasswordProperty, value); } }
        public static readonly DependencyProperty BoundPasswordProperty = DependencyProperty.Register("BoundPassword", typeof(SecureString), typeof(PasswordBoxBindingBehavior), new FrameworkPropertyMetadata(OnBoundPasswordChanged));

        protected override void OnAttached()
        {
            this.AssociatedObject.PasswordChanged += AssociatedObjectOnPasswordChanged;
            base.OnAttached();
        }

        /// <summary>
        /// Link up the intermediate SecureString (BoundPassword) to the UI instance
        /// </summary>
        private void AssociatedObjectOnPasswordChanged(object s, RoutedEventArgs e)
        {
            this.BoundPassword = this.AssociatedObject.SecurePassword;
        }

        /// <summary>
        /// Reacts to password reset on viewmodel (ViewModel.Password = new SecureString())
        /// </summary>
        private static void OnBoundPasswordChanged(object s, DependencyPropertyChangedEventArgs e)
        {
            var box = ((PasswordBoxBindingBehavior)s).AssociatedObject;
            if (box != null)
            {
                if (((SecureString)e.NewValue).Length == 0)
                    box.Password = string.Empty;
            }
        }

    }
}

如前所述，VM应该不知道视图，但传递整个PasswordBox看起来是最简单的方法。因此，可能不是将传递的参数强制转换为PasswordBox，而是使用反射从它提取Password属性。在这种情况下，虚拟机期望某种密码容器的属性密码(我使用RelayCommands从MVMM Light-Toolkit):

public RelayCommand<object> SignIn
{
    get
    {
        if (this.signIn == null)
        {
            this.signIn = new RelayCommand<object>((passwordContainer) => 
                {
                    var password = passwordContainer.GetType().GetProperty("Password").GetValue(passwordContainer) as string;
                    this.authenticationService.Authenticate(this.Login, password);
                });
        }

        return this.signIn;
    }
}

它可以很容易地用匿名类测试:

var passwordContainer = new
    {
        Password = "password"
    };

正如你所看到的，我绑定到密码，但也许它绑定到静态类..

它是一个附加属性。这种属性可以应用于任何类型的DependencyObject，而不仅仅是声明它的类型。因此，尽管它是在PasswordHelper静态类中声明的，但它还是应用于使用它的PasswordBox。

要使用这个附加属性，你只需要将它绑定到ViewModel中的Password属性:

<PasswordBox w:PasswordHelper.Attach="True" 
         w:PasswordHelper.Password="{Binding Password}"/>