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WPF PasswordBox进行数据绑定方法

运维开发网 https://www.qedev.com 2021-06-29 12:22 出处:网络 作者: louzi
本文介绍下PasswordBox进行数据绑定的方法,本文参考链接。 本文完整示例程序见github。

本文介绍下PasswordBox进行数据绑定的方法,本文参考链接。

本文完整示例程序见github。

问题描述

PasswordBox的Password属性不是依赖属性,因此无法进行数据绑定。

解决办法

该问题的解决办法有nZvPwc多种,本文介绍如何通过添加附加属性解决该问题。

附加属性是说一个属性本不属于某个对象,但由于某种需求附加到该对象上,通过附加属性可以实现将属性与宿主解耦的目的。附加属性本质上就是依赖属性,只是它们在属性包装器和注册时有区别。注册附加属性使用RegisterAttached方法,注册依赖属性使用Register方法,这两个方法的参数差别并不大。

首先添加一个PasswordBoxBindingHelper类,该类包含一个附加属性(snippet:propa+两次tab),通过设置该属性的PropertyChangedCallback将改变通知到PasswordBox.Password,并通过添加对PasswordBox.PasswordChanged事件的响应来响应PasswordBox.Password的改变。有了该附加属性,即可进行数据绑定。

public static string GetPasswordContent(DependencyObject obj) => (string)obj.GetValue(PasswordContentProperty);

public static void SetPasswordContent(DependencyObject obj, string value) => obj.SetValue(PasswordContentProperty, value);

public static readonly DependencyProperty PasswordContentProperty =
    DependencyProperty.RegisterAttached("PasswordContent", typeof(string), typeof(PasswordBoxBindingHelper),
    new PropertyMetadata(string.Empty, OnPasswordContentPropertyChanged));

private static void OnPasswordContentPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    var box = d as PasswordBox;
    box.PasswordChanged -= OnPasswordChanged;
    var password = (string)e.NewValue;
    if (box != null && 编程客栈box.Password != password)
        box.Password = password;
    box.PasswordChanged += OnPasswordChanged;
}

private static void OnPasswordChanged(object sender, RoutedEventArgs e)
{
    var box = sender as PasswordBox;
    SetPasswordContent(box, box.Password);
}

然后在View中使用该附加属性进行数据绑定,本文示例中主窗口包含一个PasswordBox控件及一个Button按钮:

// xaml 绑定附加属性
<Window ...
        xmlns:local="clr-namespace:PasswordBoxBinding"
        Title="PasswordBoxBinding" Height="300" Width="450" WindowStartupLocation="CenterScreen">

    <Grid>
        <StackPanel HorizontalAlignment="Center" Orientation="Horizontal">
            <PasswordBox MinWidth="200" Height="30" BorderBrush="LightGray" BorderThickness="2"
                         local:PasswordBoxBindingHelper.PasswordContent="{Binding Password,Mode=TwoWay}"/>
            <Rectangle Width="20"/>
            <Button Width="80" Height="30" Content="查看密码" Command="{Binding ClickedCommand}"/>
        </StackPanel>
    </Grid>
</Window>

//xaml.cs 设置绑定源
public MainWindow()
{
    InitializeComponent();
    this.DataContext = new MainWindowViewModel();
}

最后创建ViewModel进行逻辑处理:

// ViewModel
public class MainWindowViewModel : INotifyPropertyChanged
{
    public string Password
    {
        get => _password;
        set
        {
            _password = value;
            OnPropertyChanged();
        }
    }

    public DelegateCommand ClickedCommand => _clickedCommand ?? (_clickedCommand = new DelegateCommand { ExecuteAction = OnClicked });

    // 使用Cahttp://www.cppcns.comllerMemberName特性简化代码,并可以避免手动输入错误
    public void OnPropertyChanged([CallerMemberName] string name = "") => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));

    private void OnClicked(object o) => Message编程客栈Box.Show($"password: {Password}");

    public event PropertyChangedEventHandler PropertyChanged;

    private DelegateCommand _clickedCommand;
    private string _password;
}

// 实现ICommand
public class DelegateCommand : ICommand
{
    public bool CanExecute(object parameter) => CanExecuteAction?.Invoke(parameter) ?? true;

    public void Execute(object parameter) => ExecuteAction?.Invoke(parameter);

    public event EventHandler CanExecuteChanged;

    public Action<object> ExecuteAction { get; set; }
    public Func<o编程客栈bject, bool> CanExecuteAction { get; set; }
}

以上就是WPF PasswordBox进行数据绑定方法的详细内容,更多关于WPF PasswordBox数据绑定的资料请关注我们其它相关文章!

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