在一个处理程序中处理所有事件？

Question

在VB.NET中是否可以轻松编写一个事件处理程序来处理每个触发的事件？我想知道是否可以使用这样的东西制作日志记录系统.

我想做一些像(在伪代码中)的东西:

Public Sub eventHandledEvent(ByVal sender As Object, ByVal e As EventArgs)
    File.Write(sender.EventName)
End Sub

我意识到它会很慢,但它不适用于生产系统,只能作为开发工具.

Answer 1

你可以用反射做到这一点.这是如何做.使用名为的文本框创建表单TextBox1.粘贴以下代码.运行项目并查看即时窗口.

Public Class Form1

  Private Sub Form1_Activated(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Activated
    RegisterAllEvents(TextBox1, "MyEventHandler")
  End Sub

  Sub MyEventHandler(ByVal sender As Object, ByVal e As EventArgs)
    Debug.WriteLine("An event has fired: sender= " & sender.ToString & ", e=" & e.ToString)
  End Sub
  Sub RegisterAllEvents(ByVal obj As Object, ByVal methodName As String)
    'List all events through reflection'
    For Each ei As System.Reflection.EventInfo In obj.GetType().GetEvents()
      Dim handlerType As Type = ei.EventHandlerType
      Dim method As System.Reflection.MethodInfo = Me.GetType().GetMethod(methodName)
      'Create a delegate pointing to the method'
      Dim handler As [Delegate] = [Delegate].CreateDelegate(handlerType, Me, method)
      'Register the event through reflection'
      ei.AddEventHandler(obj, handler)
    Next
  End Sub
End Class

这是来自Francesco Balena的书" Programming Microsoft Visual Basic 2005 The Language".技术适用于任何引发事件的对象,而不仅仅是控件.它使用逆变.

如果您购买了本书,则会有完整的解释和一些代码,这些代码将允许您识别在通用处理程序中触发了哪个事件,并使用正则表达式来处理事件的子集.我觉得我不能在这里发布这么长的摘录.