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
好吧,这里有另一个解决方案来删除关联事件(如果你已经有一个方法来处理控件的事件):
EventDescriptor ed = TypeDescriptor.GetEvents(this.button1).Find("MouseDown",true);
Delegate delegate = Delegate.CreateDelegate(typeof(EventHandler), this, "button1_MouseDownClicked");
if(ed!=null)
ed.RemoveEventHandler(this.button1, delegate);
其他回答
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。
虽然有点晚了,但我使用了这个对我来说非常有效的链接: https://www.codeproject.com/Articles/103542/Removing-Event-Handlers-using-Reflection
这个代码的美妙之处在于它适用于所有人,WFP, Forms, Xamarin Forms。我用它来做沙玛林。请注意,只有当你不拥有这个事件(例如,一个库代码在你不关心的一些事件上崩溃)时,你才需要这种方式使用Reflection。
下面是我稍微修改过的代码:
static Dictionary<Type, List<FieldInfo>> dicEventFieldInfos = new Dictionary<Type, List<FieldInfo>>();
static BindingFlags AllBindings
{
get { return BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static; }
}
static void BuildEventFields(Type t, List<FieldInfo> lst)
{
foreach (EventInfo ei in t.GetEvents(AllBindings))
{
Type dt = ei.DeclaringType;
FieldInfo fi = dt.GetField(ei.Name, AllBindings);
if (fi != null)
lst.Add(fi);
}
}
static List<FieldInfo> GetTypeEventFields(Type t)
{
if (dicEventFieldInfos.ContainsKey(t))
return dicEventFieldInfos[t];
List<FieldInfo> lst = new List<FieldInfo>();
BuildEventFields(t, lst);
dicEventFieldInfos.Add(t, lst);
return lst;
}
static EventHandlerList GetStaticEventHandlerList(Type t, object obj)
{
MethodInfo mi = t.GetMethod("get_Events", AllBindings);
return (EventHandlerList)mi.Invoke(obj, new object[] { });
}
public static void RemoveEventHandler(object obj, string EventName = "")
{
if (obj == null)
return;
Type t = obj.GetType();
List<FieldInfo> event_fields = GetTypeEventFields(t);
EventHandlerList static_event_handlers = null;
foreach (FieldInfo fi in event_fields)
{
if (EventName != "" && string.Compare(EventName, fi.Name, true) != 0)
continue;
var eventName = fi.Name;
// After hours and hours of research and trial and error, it turns out that
// STATIC Events have to be treated differently from INSTANCE Events...
if (fi.IsStatic)
{
// STATIC EVENT
if (static_event_handlers == null)
static_event_handlers = GetStaticEventHandlerList(t, obj);
object idx = fi.GetValue(obj);
Delegate eh = static_event_handlers[idx];
if (eh == null)
continue;
Delegate[] dels = eh.GetInvocationList();
if (dels == null)
continue;
EventInfo ei = t.GetEvent(eventName, AllBindings);
foreach (Delegate del in dels)
ei.RemoveEventHandler(obj, del);
}
else
{
// INSTANCE EVENT
EventInfo ei = t.GetEvent(eventName, AllBindings);
if (ei != null)
{
object val = fi.GetValue(obj);
Delegate mdel = (val as Delegate);
if (mdel != null)
{
foreach (Delegate del in mdel.GetInvocationList())
{
ei.RemoveEventHandler(obj, del);
}
}
}
}
}
}
示例用法:RemoveEventHandler(obj, "Focused");
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);
}
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;
}
}