Question

我有Base class：

public abstract class WiresharkFile : BaseObservableObject, IDisposable
{
    private string _fileName;
    private int _packets;
    private int _packetsSent;

    public string FileName
    {
        get { return _fileName; }
        set { _fileName = value; }
    }

    public int Packets
    {
        get { return _packets; }
        set { _packets = value; }
    }

    public int PacketsSent
    {
        get { return _packetsSent; }
        set
        {
            _packetsSent = value;
            OnPropertyChanged();
        }
    }

    public void Dispose()
    {
        // Implemented insde inherit classes.
    }
}

BaseObservableObject：

public class BaseObservableObject : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        var handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }

    protected virtual void OnPropertyChanged<T>(Expression<Func<T>> raiser)
    {
        var propName = ((MemberExpression)raiser.Body).Member.Name;
        OnPropertyChanged(propName);
    }

    protected bool Set<T>(ref T field, T value, [CallerMemberName] string name = null)
    {
        if (!EqualityComparer<T>.Default.Equals(field, value))
        {
            field = value;
            OnPropertyChanged(name);
            return true;
        }
        return false;
    }
}

我的收藏：

public ObservableCollection<WiresharkFile> wiresharkFiles { get; set; }

因为你可以看到我的Base class中的avery继承类有PacketsSent属性更改所以在这种情况下一切正常。

现在我在WiresharkFile（基类）中有另一个静态属性：

private static volatile int _totalPacketsSent;

public static int TotalPacketsSent
{
    get { return _totalPacketsSent; }
    set
    {
        _totalPacketsSent = value;
        OnStaticPropertyChanged();
    }
}

所以在BaseObservableObject内我创建了这个成员：

public static event PropertyChangedEventHandler StaticPropertyChanged;

和

protected static void OnStaticPropertyChanged([CallerMemberName] string propertyName = null)
{
    var handler = StaticPropertyChanged;
    if (handler != null) handler(typeof(WiresharkFile), new PropertyChangedEventArgs(propertyName));
}

在XAML内，我想更新我的Label：

Content="{Binding Path=(my:WiresharkFile.TotalPacketsSent)}"

所以这不起作用，所以目前通过后面的代码更新Label。我做错了什么？

Answer 1

必须在类WiresharkFile中声明static属性changed事件（即也声明静态属性的类）。如果在基类中声明它将无法工作。

public class WiresharkFile : BaseObservableObject
{
    public static event PropertyChangedEventHandler StaticPropertyChanged;

    private static void OnStaticPropertyChanged(string propertyName)
    {
        var handler = StaticPropertyChanged;
        if (handler != null)
        {
            handler(null, new PropertyChangedEventArgs(propertyName));
        }
    }

    // static property here
}

Answer 2

由于您的创建PropertyChangedEventHandler不是真正的INotifyPropertyChanged接口的一部分，因此绑定不会识别抛出通知事件，因此它不会从TotalPacketsSent中提取任何新值。要使绑定刷新本身尝试这样的事情：放入WiresharkFile类：

    private static WiresharkFile This;

    public WiresharkFile()
    {
        This = this;
    }
    private static volatile int _totalPacketsSent;

    public static int TotalPacketsSent
    {
        get { return _totalPacketsSent; }
        set
        {
            _totalPacketsSent = value;
            OnStaticPropertyChanged(This);
        }
    }

- 处理程序代码：

protected static void OnStaticPropertyChanged(object sender, [CallerMemberName]string propertyName = null)
    {
        var baseObservable = sender as BaseObservableObject;
        if(baseObservable == null) return;
        baseObservable.OnPropertyChanged(propertyName);
    }

在我看来，你在BaseObservableObject类中不需要PropertyChangedEventHandler事件。

的问候，

静态INotifyPropertyChanged事件无效

2 个答案: