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
删除不存在的事件处理程序不会造成任何损害。因此,如果您知道可能存在哪些处理程序,您可以简单地删除它们。我刚遇到过类似的情况。这在某些情况下可能会有帮助。
如:
// Add handlers...
if (something)
{
c.Click += DoesSomething;
}
else
{
c.Click += DoesSomethingElse;
}
// Remove handlers...
c.Click -= DoesSomething;
c.Click -= DoesSomethingElse;
其他回答
接受的答案不完整。对于声明为{add;删除;}
下面是工作代码:
public static void ClearEventInvocations(this object obj, string eventName)
{
var fi = obj.GetType().GetEventField(eventName);
if (fi == null) return;
fi.SetValue(obj, null);
}
private static FieldInfo GetEventField(this Type type, string eventName)
{
FieldInfo field = null;
while (type != null)
{
/* Find events defined as field */
field = type.GetField(eventName, BindingFlags.Static | BindingFlags.Instance | BindingFlags.NonPublic);
if (field != null && (field.FieldType == typeof(MulticastDelegate) || field.FieldType.IsSubclassOf(typeof(MulticastDelegate))))
break;
/* Find events defined as property { add; remove; } */
field = type.GetField("EVENT_" + eventName.ToUpper(), BindingFlags.Static | BindingFlags.Instance | BindingFlags.NonPublic);
if (field != null)
break;
type = type.BaseType;
}
return field;
}
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;
}
}
我讨厌这里展示的任何完整的解决方案,我现在做了一个混合和测试,为任何事件处理程序工作:
public class MyMain()
public void MyMethod() {
AnotherClass.TheEventHandler += DoSomeThing;
}
private void DoSomething(object sender, EventArgs e) {
Debug.WriteLine("I did something");
AnotherClass.ClearAllDelegatesOfTheEventHandler();
}
}
public static class AnotherClass {
public static event EventHandler TheEventHandler;
public static void ClearAllDelegatesOfTheEventHandler() {
foreach (Delegate d in TheEventHandler.GetInvocationList())
{
TheEventHandler -= (EventHandler)d;
}
}
}
简单!感谢Stephen Punak。
我使用它是因为我使用一个通用的本地方法来删除委托,当设置不同的委托时,在不同的情况下调用本地方法。
这个页面对我帮助很大。我从这里得到的代码是为了从按钮中删除单击事件。我需要删除双击事件从一些面板和单击事件从一些按钮。所以我做了一个控件扩展,它将删除某个事件的所有事件处理程序。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms;
using System.Reflection;
public static class EventExtension
{
public static void RemoveEvents<T>(this T target, string eventName) where T:Control
{
if (ReferenceEquals(target, null)) throw new NullReferenceException("Argument \"target\" may not be null.");
FieldInfo fieldInfo = typeof(Control).GetField(eventName, BindingFlags.Static | BindingFlags.NonPublic);
if (ReferenceEquals(fieldInfo, null)) throw new ArgumentException(
string.Concat("The control ", typeof(T).Name, " does not have a property with the name \"", eventName, "\""), nameof(eventName));
object eventInstance = fieldInfo.GetValue(target);
PropertyInfo propInfo = typeof(T).GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance);
EventHandlerList list = (EventHandlerList)propInfo.GetValue(target, null);
list.RemoveHandler(eventInstance, list[eventInstance]);
}
}
现在,这个扩展的用法。 如果需要从按钮中删除单击事件,
Button button = new Button();
button.RemoveEvents(nameof(button.EventClick));
如果需要从面板中删除双击事件,
Panel panel = new Panel();
panel.RemoveEvents(nameof(panel.EventDoubleClick));
我不是c#方面的专家,所以如果有任何错误,请原谅我,并让我知道。
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(); }