C# 如何删除'；单击'；发生'；按钮'；？

我有一个按钮控件，我需要删除所有附加到其上的事件处理程序

那怎么可能呢

Button button = GetButton();
button.Click.RemoveAllEventHandlers();

---

你不能，基本上-至少不能没有反思和大量的肮脏

---

事件严格来说是“订阅，取消订阅”-你不能取消订阅其他人的处理程序，就像你不能更改其他人对对象的引用一样。

我在StackOverflow上找到了这个答案：

最初的海报发现：

注意：由于我发布原始答案的问题已结束，我将在此处交叉发布我答案的改进版本此答案仅适用于WPF。它不适用于Windows窗体或任何其他UI框架

下面是一个有用的实用程序方法，用于删除订阅给给定元素上路由事件的所有事件处理程序。如果愿意，您可以将其转换为扩展方法

/// <summary>
/// Removes all event handlers subscribed to the specified routed event from the specified element.
/// </summary>
/// <param name="element">The UI element on which the routed event is defined.</param>
/// <param name="routedEvent">The routed event for which to remove the event handlers.</param>
public static void RemoveRoutedEventHandlers(UIElement element, RoutedEvent routedEvent)
{
    // Get the EventHandlersStore instance which holds event handlers for the specified element.
    // The EventHandlersStore class is declared as internal.
    var eventHandlersStoreProperty = typeof(UIElement).GetProperty(
        "EventHandlersStore", BindingFlags.Instance | BindingFlags.NonPublic);
    object eventHandlersStore = eventHandlersStoreProperty.GetValue(element, null);

    // If no event handlers are subscribed, eventHandlersStore will be null.
    // Credit: https://stackoverflow.com/a/16392387/1149773
    if (eventHandlersStore == null)
        return;

    // Invoke the GetRoutedEventHandlers method on the EventHandlersStore instance 
    // for getting an array of the subscribed event handlers.
    var getRoutedEventHandlers = eventHandlersStore.GetType().GetMethod(
        "GetRoutedEventHandlers", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
    var routedEventHandlers = (RoutedEventHandlerInfo[])getRoutedEventHandlers.Invoke(
        eventHandlersStore, new object[] { routedEvent });

    // Iteratively remove all routed event handlers from the element.
    foreach (var routedEventHandler in routedEventHandlers)
        element.RemoveHandler(routedEvent, routedEventHandler.Handler);
}

---

Edit：我复制了，当没有订阅任何事件处理程序时，它会阻止方法抛出

NullReferenceException

。积分（和投票）应该在他们的答案上。

我有一个空错误问题，代码是杰米·迪克森（Jamie Dixon）在没有点击事件的情况下发布的

private void RemoveClickEvent(Control control)
{
    // chenged "FieldInfo f1 = typeof(Control)" to "var f1 = b.GetType()". By changing to 
    // the type of the  passed in control we can use this for any control with a click event.
    // using var allows for null checking and lowering the chance of exceptions.

    var fi = control.GetType().GetField("EventClick", BindingFlags.Static | BindingFlags.NonPublic);
    if (fi != null)
    {
        object obj = fi.GetValue(control);
        PropertyInfo pi = control.GetType().GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance);
        EventHandlerList list = (EventHandlerList)pi.GetValue(control, null);
        list.RemoveHandler(obj, list[obj]);
    }

}

然后是一个小的变化，它应该是为任何事件

private void RemoveClickEvent(Control control, string theEvent)
{
    // chenged "FieldInfo f1 = typeof(Control)" to "var f1 = b.GetType()". By changing to 
    // the type of the  passed in control we can use this for any control with a click event.
    // using var allows for null checking and lowering the chance of exceptions.

    var fi = control.GetType().GetField(theEvent, BindingFlags.Static | BindingFlags.NonPublic);
    if (fi != null)
    {
        object obj = fi.GetValue(control);
        PropertyInfo pi = control.GetType().GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance);
        EventHandlerList list = (EventHandlerList)pi.GetValue(control, null);
        list.RemoveHandler(obj, list[obj]);
    }

}

---

我想这可以做得更好，但它符合我目前的需要。希望这对某人有用

只是想稍微扩展一下道格拉斯的常规，我非常喜欢。 我发现我需要向eventHandlersStore添加额外的null检查，以处理传递的元素尚未附加任何事件的情况

/// <summary>
/// Removes all event handlers subscribed to the specified routed event from the specified element.
/// </summary>
/// <param name="element">The UI element on which the routed event is defined.</param>
/// <param name="routedEvent">The routed event for which to remove the event handlers.</param>
public static void RemoveRoutedEventHandlers(UIElement element, RoutedEvent routedEvent)
{
    // Get the EventHandlersStore instance which holds event handlers for the specified element.
    // The EventHandlersStore class is declared as internal.
    var eventHandlersStoreProperty = typeof(UIElement).GetProperty(
        "EventHandlersStore", BindingFlags.Instance | BindingFlags.NonPublic);
    object eventHandlersStore = eventHandlersStoreProperty.GetValue(element, null);

    if (eventHandlersStore == null) return;

    // Invoke the GetRoutedEventHandlers method on the EventHandlersStore instance 
    // for getting an array of the subscribed event handlers.
    var getRoutedEventHandlers = eventHandlersStore.GetType().GetMethod(
        "GetRoutedEventHandlers", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
    var routedEventHandlers = (RoutedEventHandlerInfo[])getRoutedEventHandlers.Invoke(
        eventHandlersStore, new object[] { routedEvent });

    // Iteratively remove all routed event handlers from the element.
    foreach (var routedEventHandler in routedEventHandlers)
        element.RemoveHandler(routedEvent, routedEventHandler.Handler);
}

//
///从指定元素中删除订阅指定路由事件的所有事件处理程序。
/// 
///定义路由事件的UI元素。
///要删除其事件处理程序的路由事件。
公共静态空隙清除器OutDeventhandler（UIElement元素，RoutedEvent RoutedEvent）
{
//获取EventHandlersStore实例，该实例保存指定元素的事件处理程序。
//EventHandlersStore类声明为内部。
var eventHandlersStoreProperty=typeof（UIElement）.GetProperty(
“EventHandlersStore”，BindingFlags.Instance | BindingFlags.NonPublic）；
对象eventHandlersStore=eventHandlersStoreProperty.GetValue（元素，null）；
if（eventHandlersStore==null）返回；
//在EventHandlersStore实例上调用GetRoutedEventHandlers方法
//用于获取订阅的事件处理程序数组。
var getRoutedEventHandlers=eventHandlersStore.GetType（）.GetMethod(
“GetRoutedEventHandler”，BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic）；
var routedEventHandlers=（RoutedEventHandlerInfo[]）getRoutedEventHandlers.Invoke(
eventHandlersStore，新对象[]{routedEvent}）；
//迭代地从元素中删除所有路由事件处理程序。
foreach（路由EventHandler中的变量routedEventHandler）
元素。RemoveHandler（routedEvent，routedEventHandler.Handler）；
}

我正在处理WinForms项目，在该项目中，我必须从ToolStripMenuItem中删除click EventHandler，并将其替换为我自己的处理程序。（我必须修改单击上下文菜单项时采取的操作）

对我来说，来自user2113340的代码不起作用。为了使用ToolStripMenuItem，我不得不这样修改它：

    private void RemoveClickEvent(ToolStripMenuItem control)
    {
        FieldInfo eventClick = typeof(Control).GetField("EventClick", BindingFlags.NonPublic | BindingFlags.Static);
        PropertyInfo eventsProp = typeof(Component).GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance);
        EventHandlerList events = (EventHandlerList)eventsProp.GetValue(control, null);
        FieldInfo headInfo = events.GetType().GetField("head", BindingFlags.NonPublic | BindingFlags.Instance);
        object head = headInfo.GetValue(events);
        FieldInfo keyType = head.GetType().GetField("key", BindingFlags.NonPublic | BindingFlags.Instance);
        object key = keyType.GetValue(head);
        Delegate d1 = events[key];
        events.RemoveHandler(key, d1);
    }

---

不过这是具体实现的问题——答案出现在2008年，我甚至不想说它是否能在.NET4上运行。依赖这样的东西是一个非常糟糕的主意。谢谢，但是这一行总是返回null:typeof（Control）.GetField（“EventClick”，BindingFlags.Static | BindingFlags.NonPublic）；我实现了一个类似的解决方案，该解决方案使用EventHandlerList对象的几个内部方法。查看答案你能用MyButtonClass替换Button吗？我想更简单的方法是禁用Button我想在之后只添加一个事件处理程序，所以禁用不会有帮助。可能重复我知道这是一个非常老的问题，但我认为您可能应该将所选答案改为道格拉斯给出的反射选项。“你不能”是一个非常糟糕的答案，尤其是当有一个非常好的例子表明你现在可以的时候；取消订阅其他人的处理程序！我正在使用第三方的自定义按钮，并希望删除作者的单击事件处理程序…@William：基本上，如果不依赖实现细节和反射，就不能删除，除非自定义按钮公开此类行为。事件的封装是为了处理程序不会相互干扰。@William:1）您使用控件的方式不是为它设计的，因此很容易造成问题。2） 您的解决方案很可能在将来的版本中中断。3） 它在信任度低的环境中不起作用。基本上，你希望你的代码有多脆弱；考虑设计而不仅仅是实现。我已经创建了自己的自定义按钮，并从原始按钮复制了我需要的（图标等）。是否可以在silverlight中执行此操作？silverlight没有路由EventHandlerInfo。。。。是否可以将其扩展为扩展方法？那太好了。。。

/// <summary>
/// Removes all event handlers subscribed to the specified routed event from the specified element.
/// </summary>
/// <param name="element">The UI element on which the routed event is defined.</param>
/// <param name="routedEvent">The routed event for which to remove the event handlers.</param>
public static void RemoveRoutedEventHandlers(UIElement element, RoutedEvent routedEvent)
{
    // Get the EventHandlersStore instance which holds event handlers for the specified element.
    // The EventHandlersStore class is declared as internal.
    var eventHandlersStoreProperty = typeof(UIElement).GetProperty(
        "EventHandlersStore", BindingFlags.Instance | BindingFlags.NonPublic);
    object eventHandlersStore = eventHandlersStoreProperty.GetValue(element, null);

    if (eventHandlersStore == null) return;

    // Invoke the GetRoutedEventHandlers method on the EventHandlersStore instance 
    // for getting an array of the subscribed event handlers.
    var getRoutedEventHandlers = eventHandlersStore.GetType().GetMethod(
        "GetRoutedEventHandlers", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
    var routedEventHandlers = (RoutedEventHandlerInfo[])getRoutedEventHandlers.Invoke(
        eventHandlersStore, new object[] { routedEvent });

    // Iteratively remove all routed event handlers from the element.
    foreach (var routedEventHandler in routedEventHandlers)
        element.RemoveHandler(routedEvent, routedEventHandler.Handler);
}

    private void RemoveClickEvent(ToolStripMenuItem control)
    {
        FieldInfo eventClick = typeof(Control).GetField("EventClick", BindingFlags.NonPublic | BindingFlags.Static);
        PropertyInfo eventsProp = typeof(Component).GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance);
        EventHandlerList events = (EventHandlerList)eventsProp.GetValue(control, null);
        FieldInfo headInfo = events.GetType().GetField("head", BindingFlags.NonPublic | BindingFlags.Instance);
        object head = headInfo.GetValue(events);
        FieldInfo keyType = head.GetType().GetField("key", BindingFlags.NonPublic | BindingFlags.Instance);
        object key = keyType.GetValue(head);
        Delegate d1 = events[key];
        events.RemoveHandler(key, d1);
    }