wpf 如何在没有数据绑定的情况下登录失败时清除密码框的内容？
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How to clear the contents of a PasswordBox when login fails without databinding?
提问by Price Jones
I have a wpf application and I am following the mvvm pattern carefully for reasons beyond my control. I do not want to databind to my PasswordBox for security reasons beyond my control. How do I clear the contents of the password box when the login fails? I would prefer a way to do so in xaml.
我有一个 wpf 应用程序，由于我无法控制的原因，我正在仔细遵循 mvvm 模式。出于我无法控制的安全原因，我不想将数据绑定到我的 PasswordBox。登录失败时如何清除密码框中的内容？我更喜欢在 xaml 中这样做的方法。
回答by Anatoliy Nikolaev
You can create your attachedDependencyPropertyand use it as a XAML or in code. Example:
您可以创建您的附件DependencyProperty并将其用作 XAML 或在代码中使用。例子：
Listing of PasswordBehaviors:
清单PasswordBehaviors：
public static class PasswordBehaviors
{
public static void SetIsClear(DependencyObject target, bool value)
{
target.SetValue(IsClearProperty, value);
}
public static readonly DependencyProperty IsClearProperty =
DependencyProperty.RegisterAttached("IsClear",
typeof(bool),
typeof(PasswordBehaviors),
new UIPropertyMetadata(false, OnIsClear));
private static void OnIsClear(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
if (e.NewValue is bool && ((bool)e.NewValue) == true)
{
PasswordBox MyPasswordBox = sender as PasswordBox;
if (MyPasswordBox != null)
{
MyPasswordBox.Clear();
}
}
}
}
Using with EventTrigger:
使用EventTrigger：
<EventTrigger SourceName="Clear" RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="MyPasswordBox" Storyboard.TargetProperty="(local:PasswordBehaviors.IsClear)">
<DiscreteObjectKeyFrame KeyTime="0:0:0">
<DiscreteObjectKeyFrame.Value>
<sys:Boolean>True</sys:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
Using with DataTrigger(in Style/DataTemplate/etc):
与使用DataTrigger（在Style/ DataTemplate/ etc）：
<DataTrigger Binding="{Binding ElementName=LoginElementFailed, Path=Status), Mode=OneWay}" Value="True">
<Setter Property="(local:PasswordBehaviors.IsClear)" Value="True" />
</DataTrigger>
Using with Trigger(in Style):
与Trigger(in Style) 一起使用：
<Trigger Property="LoginFailed.IsChecked" Value="True">
<Setter Property="(local:PasswordBehaviors.IsClear)" Value="True" />
</Trigger>
Using behind code:
使用后面的代码：
private void Clear_Click(object sender, RoutedEventArgs e)
{
PasswordBehaviors.SetIsClear(MyPasswordBox, true);
}
Copmlete example:
完整示例：
XAML
XAML
<Window x:Class="ClearPasswordBox.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:ClearPasswordBox"
xmlns:sys="clr-namespace:System;assembly=mscorlib"
Title="MainWindow" Height="350" Width="525"
WindowStartupLocation="CenterScreen">
<Grid>
<Grid.Triggers>
<EventTrigger SourceName="Clear" RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="MyPasswordBox" Storyboard.TargetProperty="(local:PasswordBehaviors.IsClear)">
<DiscreteObjectKeyFrame KeyTime="0:0:0">
<DiscreteObjectKeyFrame.Value>
<sys:Boolean>True</sys:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
<EventTrigger SourceName="ResetClear" RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="MyPasswordBox" Storyboard.TargetProperty="(local:PasswordBehaviors.IsClear)">
<DiscreteObjectKeyFrame KeyTime="0:0:0">
<DiscreteObjectKeyFrame.Value>
<sys:Boolean>False</sys:Boolean>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Grid.Triggers>
<PasswordBox Name="MyPasswordBox" local:PasswordBehaviors.IsClear="False" Width="100" Height="30" />
<Button Name="Clear" Width="100" Height="30" HorizontalAlignment="Right" Content="Clear" />
<Button Name="ResetClear" Width="100" Height="30" HorizontalAlignment="Left" Content="ResetClear" />
</Grid>
</Window>
Code behind
Code behind
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
//private void Clear_Click(object sender, RoutedEventArgs e)
//{
// PasswordBehaviors.SetIsClear(MyPasswordBox, true);
//}
//private void ResetClear_Click(object sender, RoutedEventArgs e)
//{
// PasswordBehaviors.SetIsClear(MyPasswordBox, false);
//}
}
public static class PasswordBehaviors
{
public static void SetIsClear(DependencyObject target, bool value)
{
target.SetValue(IsClearProperty, value);
}
public static readonly DependencyProperty IsClearProperty =
DependencyProperty.RegisterAttached("IsClear",
typeof(bool),
typeof(PasswordBehaviors),
new UIPropertyMetadata(false, OnIsClear));
private static void OnIsClear(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
if (e.NewValue is bool && ((bool)e.NewValue) == true)
{
PasswordBox MyPasswordBox = sender as PasswordBox;
if (MyPasswordBox != null)
{
MyPasswordBox.Clear();
}
}
}
}
