通过c＃中的反射来提升事件 [英] Raise an event via reflection in c#

问题描述

我想要写一个可重用的功能来通过反射来引发一个事件。

I want to write a reusable function to raise an event via reflection.

搜索后，我发现这个类似的问题：如何通过反思在.NET / C＃？

After searching, I found this similar question: How do I raise an event via reflection in .NET/C#?

它工作，直到我注册一个事件处理程序到WinForm控件，并尝试调用它。私人字段'< EventName> '简单地消失。

It works until I register an event handler to WinForm control and try to invoke it. The private field '<EventName>' simply disappears.

以下是我简化的代码，重现了这个问题：

Below is my simplified code which reproduces the problem:

Program.cs：

Program.cs:

public static void Main()
{
    Control control = new Control();
    control.Click += new EventHandler(control_Click);

    MethodInfo eventInvoker = ReflectionHelper.GetEventInvoker(control, "Click");
    eventInvoker.Invoke(control, new object[] {null, null});
}

static void control_Click(object sender, EventArgs e)
{
    Console.WriteLine("Clicked !!!!!!!!!!!");
}

这是我的ReflectionHelper类：

Here is my ReflectionHelper class:

public static class ReflectionHelper
{
    /// <summary>
    /// Gets method that will be invoked the event is raised.
    /// </summary>
    /// <param name="obj">Object that contains the event.</param>
    /// <param name="eventName">Event Name.</param>
    /// <returns></returns>
    public static MethodInfo GetEventInvoker(object obj, string eventName)
    {
        // --- Begin parameters checking code -----------------------------
        Debug.Assert(obj != null);
        Debug.Assert(!string.IsNullOrEmpty(eventName));
        // --- End parameters checking code -------------------------------

        // prepare current processing type
        Type currentType = obj.GetType();

        // try to get special event decleration
        while (true)
        {
            FieldInfo fieldInfo = currentType.GetField(eventName, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.GetField);

            if (fieldInfo == null)
            {
                if (currentType.BaseType != null)
                {
                    // move deeper
                    currentType = currentType.BaseType;
                    continue;
                }

                Debug.Fail(string.Format("Not found event named {0} in object type {1}", eventName, obj));
                return null;
            }

            // found
            return ((MulticastDelegate)fieldInfo.GetValue(obj)).Method;
        }
    }

附加信息：

• 同一类的事件：工作。


• 事件在不同的类中，子类在同一个程序集中：工作。


• 事件在 MY 不同的程序集，调试和释放模式：工作。


• WinForm，DevExpress，...中的事件：没有工作

• Event in same class: worked.
• Event in different class, sub-class in same assembly: worked.
• Event in MY different assembly, debug & release mode: worked.
• Event in WinForm, DevExpress, ...: did not work

任何帮助赞赏。

推荐答案

WinForms中的事件通常被覆盖，而不是一个一对一的委托支持。相反，类（基本上）具有事件 - >委托映射的字典，并且仅在添加事件时才创建代理。所以你不能假设有一个代理人支持事件，一旦你访问了反射的领域。

Events in WinForms are generally overridden and not don't have a one-to-one delegate backing. Instead the class (basically) has a dictionary of the event->delegate mappings and the delegates are only created when the events are added. So you can't assume there's a delegate backing the event once you access the field with reflection.

编辑：这是同样的问题的牺牲品，但比获得它作为一个字段并投射它。

this falls prey to the same problem, but is better than getting it as a field and casting it.

  var eventInfo = currentType.GetEvent(eventName); 
  var eventRaiseMethod = eventInfo.GetRaiseMethod()
  eventRaiseMethod.Invoke()

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