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

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;
    }
}

其他回答

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(); }

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。

我在MSDN论坛上找到了一个解决方案。下面的示例代码将删除button1中的所有Click事件。

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        button1.Click += button1_Click;
        button1.Click += button1_Click2;
        button2.Click += button2_Click;
    }

    private void button1_Click(object sender, EventArgs e)  => MessageBox.Show("Hello");
    private void button1_Click2(object sender, EventArgs e) => MessageBox.Show("World");
    private void button2_Click(object sender, EventArgs e)  => RemoveClickEvent(button1);

    private void RemoveClickEvent(Button b)
    {
        FieldInfo f1 = typeof(Control).GetField("EventClick", 
            BindingFlags.Static | BindingFlags.NonPublic);

        object obj = f1.GetValue(b);
        PropertyInfo pi = b.GetType().GetProperty("Events",  
            BindingFlags.NonPublic | BindingFlags.Instance);

        EventHandlerList list = (EventHandlerList)pi.GetValue(b, null);
        list.RemoveHandler(obj, list[obj]);
    }
}

我刚刚发现如何在设置WinForms控件的属性时挂起事件。它将删除控件中的所有事件:

namespace CMessWin05
{
    public class EventSuppressor
    {
        Control _source;
        EventHandlerList _sourceEventHandlerList;
        FieldInfo _headFI;
        Dictionary<object, Delegate[]> _handlers;
        PropertyInfo _sourceEventsInfo;
        Type _eventHandlerListType;
        Type _sourceType;


        public EventSuppressor(Control control)
        {
            if (control == null)
                throw new ArgumentNullException("control", "An instance of a control must be provided.");

            _source = control;
            _sourceType = _source.GetType();
            _sourceEventsInfo = _sourceType.GetProperty("Events", BindingFlags.Instance | BindingFlags.NonPublic);
            _sourceEventHandlerList = (EventHandlerList)_sourceEventsInfo.GetValue(_source, null);
            _eventHandlerListType = _sourceEventHandlerList.GetType();
            _headFI = _eventHandlerListType.GetField("head", BindingFlags.Instance | BindingFlags.NonPublic);
        }

        private void BuildList()
        {
            _handlers = new Dictionary<object, Delegate[]>();
            object head = _headFI.GetValue(_sourceEventHandlerList);
            if (head != null)
            {
                Type listEntryType = head.GetType();
                FieldInfo delegateFI = listEntryType.GetField("handler", BindingFlags.Instance | BindingFlags.NonPublic);
                FieldInfo keyFI = listEntryType.GetField("key", BindingFlags.Instance | BindingFlags.NonPublic);
                FieldInfo nextFI = listEntryType.GetField("next", BindingFlags.Instance | BindingFlags.NonPublic);
                BuildListWalk(head, delegateFI, keyFI, nextFI);
            }
        }

        private void BuildListWalk(object entry, FieldInfo delegateFI, FieldInfo keyFI, FieldInfo nextFI)
        {
            if (entry != null)
            {
                Delegate dele = (Delegate)delegateFI.GetValue(entry);
                object key = keyFI.GetValue(entry);
                object next = nextFI.GetValue(entry);

                Delegate[] listeners = dele.GetInvocationList();
                if(listeners != null && listeners.Length > 0)
                    _handlers.Add(key, listeners);

                if (next != null)
                {
                    BuildListWalk(next, delegateFI, keyFI, nextFI);
                }
            }
        }

        public void Resume()
        {
            if (_handlers == null)
                throw new ApplicationException("Events have not been suppressed.");

            foreach (KeyValuePair<object, Delegate[]> pair in _handlers)
            {
                for (int x = 0; x < pair.Value.Length; x++)
                    _sourceEventHandlerList.AddHandler(pair.Key, pair.Value[x]);
            }

            _handlers = null;
        }

        public void Suppress()
        {
            if (_handlers != null)
                throw new ApplicationException("Events are already being suppressed.");

            BuildList();

            foreach (KeyValuePair<object, Delegate[]> pair in _handlers)
            {
                for (int x = pair.Value.Length - 1; x >= 0; x--)
                    _sourceEventHandlerList.RemoveHandler(pair.Key, pair.Value[x]);
            }
        }

    }
}

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。