如何删除“Click”的所有事件处理程序？ “按钮”事件？

Question

我有一个按钮控件，我需要删除附加到其 点击事件。

这怎么可能呢？

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

Answer 1

注意：由于我发布原始答案的问题已被关闭作为重复 对于这个问题，我在这里交叉发布了我的答案的改进版本。 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方法，用于删除订阅给定元素上的路由事件的所有事件处理程序。如果您愿意，您可以轻松地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);
}

然后，您可以轻松地为按钮的 Click 事件调用此实用程序方法：

RemoveRoutedEventHandlers(button, Button.ClickEvent);

编辑：我已复制 corona 实现的错误修复，该修复可阻止该方法在没有订阅事件处理程序时抛出 NullReferenceException。他们的回答应该得到赞扬（和支持）。

Answer 2

只是想稍微扩展道格拉斯的日常，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任何情况。

/// <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);
}

Answer 3

基本上你不能——至少在没有反思和大量肮脏的情况下不能。

事件严格来说是“订阅、取消订阅”——您无法取消订阅其他人的处理程序，就像您无法更改其他人对对象的引用一样。

Answer 4

我在 StackOverflow 上找到了这个答案：

如何删除所有事件处理程序 控件

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]);
}

来自原始发布者发现的 此处：

Answer 5

我在 Jamie Dixon 发布的代码中遇到了空错误问题，以考虑没有 Click 事件。

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]);
    }

}

然后做一个小的改变，它应该适用于任何事件。

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，但它适合我当前的需求。希望这对某人有用。

Answer 6

我正在开发 WinForms 项目，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 contextMenu 项时所采取的操作）

对我来说，来自 user2113340 的代码不起作用。我必须像这样修改它才能与 ToolStripMenuItem 一起使用：

    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);
    }