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我正在尝试使用 GetField() 以从实现 INotifyPropertyChanged 的​​类的基于 Castle 的动态代理获取 EventHandler。然而：

myObject.GetType().GetField( "PropertyChanged", BindingFlags.GetField | BindingFlags.NonPublic | BindingFlags.Instance ) 返回空值。

有谁知道通过反射从类/类的动态代理（并调用任何订阅者）获取 EventHandler 的任何特殊技巧/方法？

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1 回答 1

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这是如何PropertyChanged通过反射获取事件并触发它的示例。
应该适用于任何类型，甚至适用于基于 Castle 的动态代理。唯一的要求是PropertyChanged存在。
代码：

使用系统；使用 System.Collections.Generic；使用 System.ComponentModel；使用 System.Reflection；

命名空间 ConsoleApplication1 { 内部类 FooDerived : Foo { }

internal class Foo : INotifyPropertyChanged
{
    private string someProperty;

    public string SomeProperty
    {
        get { return someProperty; }
        set
        {
            someProperty = value;
            OnPropertyChanged("SomeProperty");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

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

class Program
{
    static void Main(string[] args)
    {
        var instance = new FooDerived();
        instance.PropertyChanged += (sender, e) => Console.WriteLine("Property '{0}' has been changed!", e.PropertyName);

        FireEventOn(instance: instance,
                    eventName: "PropertyChanged",
                    createEventArgs: () => new PropertyChangedEventArgs(propertyName: "SomeProperty"));
    }

    // only not null reference to instance is needed
    // so will work on any not null instance
    // of any type
    private static void FireEventOn(object instance, string eventName, Func<object> createEventArgs)
    {
        BindingFlags flags = BindingFlags.Instance | BindingFlags.NonPublic;
        FieldInfo e = GetEvent(eventName, instance.GetType(), lookupWholHierarchy: true);
        var eventDelegate = (MulticastDelegate)e.GetValue(instance);
        if(eventDelegate == null)
        {
             // nothing to call
             return;
        }

        foreach (Delegate d in eventDelegate.GetInvocationList())
        {
            Console.Write("Dynamically firing the event: ");
            d.Method.Invoke(d.Target, new[] { instance, createEventArgs() });
        }
    }

    private static FieldInfo GetEvent(string eventName, Type type, bool lookupWholHierarchy = false)
    {
        if (!lookupWholHierarchy)
        {
            return type.GetField(eventName, BindingFlags.Instance | BindingFlags.NonPublic);
        }
        else
        {
            foreach (var t in GetHierarchy(type))
            {
                var e = t.GetField(eventName, BindingFlags.Instance | BindingFlags.NonPublic);
                if (e != null)
                {
                    return e;
                }
            }
        }

        return null;
    }

    private static IEnumerable<Type> GetHierarchy(Type startFrom)
    {
        var current = startFrom;
        while (current != null)
        {
            yield return current;
            current = current.BaseType;
        }
    }


   }
}

希望这可以帮助。

编辑
更新了代码：添加了（相当愚蠢的）逻辑，用于通过整个继承层次结构查找事件。

于 2014-04-03T23:16:25.357 回答