要在控件上创建新的事件处理程序,可以这样做
c.Click += new EventHandler(mainFormButton_Click);
或者这个
c.Click += mainFormButton_Click;
要删除事件处理程序,可以这样做
c.Click -= mainFormButton_Click;
但是如何从事件中删除所有事件处理程序呢?
要在控件上创建新的事件处理程序,可以这样做
c.Click += new EventHandler(mainFormButton_Click);
或者这个
c.Click += mainFormButton_Click;
要删除事件处理程序,可以这样做
c.Click -= mainFormButton_Click;
但是如何从事件中删除所有事件处理程序呢?
当前回答
哇。我找到了这个解决方案,但没有一个像我想要的那样有效。但这个太好了:
EventHandlerList listaEventos;
private void btnDetach_Click(object sender, EventArgs e)
{
listaEventos = DetachEvents(comboBox1);
}
private void btnAttach_Click(object sender, EventArgs e)
{
AttachEvents(comboBox1, listaEventos);
}
public EventHandlerList DetachEvents(Component obj)
{
object objNew = obj.GetType().GetConstructor(new Type[] { }).Invoke(new object[] { });
PropertyInfo propEvents = obj.GetType().GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance);
EventHandlerList eventHandlerList_obj = (EventHandlerList)propEvents.GetValue(obj, null);
EventHandlerList eventHandlerList_objNew = (EventHandlerList)propEvents.GetValue(objNew, null);
eventHandlerList_objNew.AddHandlers(eventHandlerList_obj);
eventHandlerList_obj.Dispose();
return eventHandlerList_objNew;
}
public void AttachEvents(Component obj, EventHandlerList eventos)
{
PropertyInfo propEvents = obj.GetType().GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance);
EventHandlerList eventHandlerList_obj = (EventHandlerList)propEvents.GetValue(obj, null);
eventHandlerList_obj.AddHandlers(eventos);
}
其他回答
如果你真的要这么做……这需要深思熟虑和相当长的时间。事件处理程序在控件内的事件委托映射中进行管理。你需要
在控件实例中反射并获取此映射。 迭代每个事件,获取委托 每个委托可以依次是一系列链接的事件处理程序。调用obControl。RemoveHandler(事件处理程序)
简而言之,工作量很大。在理论上是可能的。我从没试过这样的东西。
看看是否可以对订阅-退订阶段有更好的控制/纪律。
实际上我在用这个方法,效果很好。我受到了Aeonhack写的代码的“启发”。
Public Event MyEvent()
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
If MyEventEvent IsNot Nothing Then
For Each d In MyEventEvent.GetInvocationList ' If this throws an exception, try using .ToArray
RemoveHandler MyEvent, d
Next
End If
End Sub
~MyClass()
{
if (MyEventEvent != null)
{
foreach (var d in MyEventEvent.GetInvocationList())
{
MyEventEvent -= (MyEvent)d;
}
}
}
字段MyEventEvent是隐藏的,但它确实存在。
调试过程中,你可以看到d.t target是如何实际处理事件的对象,而d.m ode是如何处理事件的方法。你只需要把它拿掉。
效果很好。不再有对象因为事件处理程序而被GC。
从删除所有事件处理程序:
Directly no, in large part because you cannot simply set the event to null. Indirectly, you could make the actual event private and create a property around it that tracks all of the delegates being added/subtracted to it. Take the following: List<EventHandler> delegates = new List<EventHandler>(); private event EventHandler MyRealEvent; public event EventHandler MyEvent { add { MyRealEvent += value; delegates.Add(value); } remove { MyRealEvent -= value; delegates.Remove(value); } } public void RemoveAllEvents() { foreach(EventHandler eh in delegates) { MyRealEvent -= eh; } delegates.Clear(); }
这不是对OP的回答,但我想我把它贴在这里,以防它能帮助到其他人。
/// <summary>
/// Method to remove a (single) SocketAsyncEventArgs.Completed event handler. This is
/// partially based on information found here: http://stackoverflow.com/a/91853/253938
///
/// But note that this may not be a good idea, being very .Net implementation-dependent. Note
/// in particular use of "m_Completed" instead of "Completed".
/// </summary>
private static void RemoveCompletedEventHandler(SocketAsyncEventArgs eventArgs)
{
FieldInfo fieldInfo = typeof(SocketAsyncEventArgs).GetField("m_Completed",
BindingFlags.Instance | BindingFlags.NonPublic);
eventArgs.Completed -= (EventHandler<SocketAsyncEventArgs>)fieldInfo.GetValue(eventArgs);
}
你们对自己太苛刻了。很简单:
void OnFormClosing(object sender, FormClosingEventArgs e)
{
foreach(Delegate d in FindClicked.GetInvocationList())
{
FindClicked -= (FindClickedHandler)d;
}
}