在程序设计中有时候需要动态订阅客户自己的事件，调用完成后又要删除以前订阅的事件。因为如果不删除，有时会造成事件是会重复订阅，导致程序运行异常。一个办法是用反射来控件事件列表。清空方法代码如下：
/// <summary>
/// 清空控件的事件列表
/// </summary>
/// <param name="pControl">要清空事件列表的控件</param>
/// <param name="pEventName">事件名</param>
void ClearEvent(Control pControl, string pEventName)
{
if (pControl== null) return;
if (string.IsNullOrEmpty(pEventName)) return;
BindingFlags mPropertyFlags = BindingFlags.Instance | BindingFlags.Public
| BindingFlags.Static | BindingFlags.NonPublic;//筛选
BindingFlags mFieldFlags = BindingFlags.Static | BindingFlags.NonPublic;
Type controlType = typeof(System.Windows.Forms.Control);
PropertyInfo propertyInfo = controlType.GetProperty("Events", mPropertyFlags);
EventHandlerList eventHandlerList = (EventHandlerList)propertyInfo.GetValue(pControl, null);//事件列表
FieldInfo fieldInfo = (typeof(Control)).GetField("Event" + pEventName, mFieldFlags);
Delegate d = eventHandlerList[fieldInfo.GetValue(pControl)];
if (d == null) return;
EventInfo eventInfo=controlType.GetEvent(pEventName);
foreach (Delegate dx in d.GetInvocationList())
eventInfo.RemoveEventHandler(pControl, dx);//移除已订阅的pEventName类型事件
}
这种方法可以一劳永逸，简单方便。但由于引入了反射，涉及到的数据类型，编译器是无法检查的，容易给程序运行时带来不稳定因素。
以上转载的，我是要用来判断ArcEngine中PageLayoutControl控件的事件是否绑定处理函数的，由于MS事件机制的修改，已经不能通过==null的方式来判断事件是否绑定函数了，需要用到反射，这个例子虽然短，不过刚好能说明情况
Type t = typeof(AxPageLayoutControl);
System.Reflection.FieldInfo fieldInfo = t.GetField("OnDoubleClick", myBindingFlags);
Delegate instanceDelegate = fieldInfo.GetValue(axPageLayoutControl1) as Delegate;
string msg = "";
if (instanceDelegate != null)
{
foreach (Delegate d in instanceDelegate.GetInvocationList())
{
//c.OnChange -= d as EventHandler;
////evt.RemoveEventHandler(c, d as EventHandler);
msg += d.Method.Name;
}
}
MessageBox.Show("deligate is:" + msg);
这样就能把PageLayoutControl的OnDoubleClick绑定的所有函数的名称输出出来
可以进一步修改
出处：http://www.cnblogs.com/caodajieup/archive/2011/09/29/2195117.html
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[C#应用]得到组件事件的委托列表
public static Delegate[] GetComponentEventDelegate(Component component, string EventName, string EventHandlerTypeName) { Type componentType = component.GetType(); PropertyInfo eventsPropertyInfo = componentType.GetProperty("Events", BindingFlags.Instance | BindingFlags.NonPublic); EventHandlerList eventHanlderList = eventsPropertyInfo.GetValue(component, null) as EventHandlerList; FieldInfo HeadFieldInfo = eventHanlderList.GetType().GetField("head", BindingFlags.Instance | BindingFlags.NonPublic); object HeadObject = HeadFieldInfo.GetValue(eventHanlderList); do { FieldInfo[] fieldInfoList = componentType.GetFields(BindingFlags.Static | BindingFlags.Instance | BindingFlags.NonPublic); foreach (FieldInfo fieldInfo in fieldInfoList) { object fieldValue = fieldInfo.GetValue(component); if (fieldValue != null) { Type fieldType = fieldValue.GetType(); if (fieldType.Name == EventHandlerTypeName && (fieldValue as Delegate) != null) { return (fieldValue as Delegate).GetInvocationList(); } else if (fieldType.Name == typeof(Object).Name) { if (fieldInfo.Name.IndexOf(EventName, StringComparison.OrdinalIgnoreCase) > -1) { if (HeadObject != null) { Delegate delegateObject = eventHanlderList[fieldValue]; if (delegateObject != null) return delegateObject.GetInvocationList(); } } } } } componentType = componentType.BaseType; } while (componentType != null); if (HeadObject != null) { object ListEntry = HeadObject; Type ListEntryType = ListEntry.GetType(); FieldInfo handlerFieldInfo = ListEntryType.GetField("handler", BindingFlags.Instance | BindingFlags.NonPublic); FieldInfo keyFieldInfo = ListEntryType.GetField("key", BindingFlags.Instance | BindingFlags.NonPublic); FieldInfo nextFieldInfo = ListEntryType.GetField("next", BindingFlags.Instance | BindingFlags.NonPublic); while (ListEntry != null) { Delegate handler = handlerFieldInfo.GetValue(ListEntry) as Delegate; object key = keyFieldInfo.GetValue(ListEntry); ListEntry = nextFieldInfo.GetValue(ListEntry); if (handler != null && handler.GetType().Name == EventHandlerTypeName) return handler.GetInvocationList(); } } return null; }
简要说明:
1)参数说明:
component: 组件对象实例
EventName: 事件的名称,如"ItemClick"
EventHandlerTypeName: 事件委托类型,如"ItemClickEventHander"
2)代码说明:
第一段代码遍历组件的所有私有字段,尝试根据EventName和EventHandlerTypeName找出相关的字段.
如果找到了相关的字段,检查它的值是否是Delegate类型,是的话OK.如果它的值是Object类型,那么说明它是EventHandlerList的key,则需要用EventHandlerList实例[key]来得到委托列表.
第二段代码在第一段代码没找到对应的字段的情况下，检查EventHandlerList是否为空，不为空的话。遍历该组件的所有事件，尝试使用EventHandlerTypeName来找到相关的委托列表。
如果还未找到，则返回null。
3)存在的问题
可能无法找到某些组件的委托，或者找到不匹配的委托列表。
能否顺利地找到事件对应的委托列表，取决于组件内部定义的事件字段或在EventHandlerList的key字段是否与事件名称相同以及EventHandler类型是否特殊。
如果组件内部定义了与事件名称相同的字段或EventHandler类型比较特别，则较容易找到对应的委托列表。
虽然可以通过EventHandlerList来得到组件的所有事件委托，但根据得到的key却无法确定handler委托列表对应的是哪一个事件。
4)已检测过的组件和事件
没来得及仔细测试，只测试了二个XtraBar的BarButtonItem.ItemClick和XtraNavBar的NavBarItem.LinkClicked事件。
出处：https://blog.csdn.net/zxkid/article/details/1444396
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C#如何知道控件注册了哪些事件，是通过代码获取这个控件的已注册事件列表
EventInfo[] memberinfo = (typeof(System.Windows.Forms.Button)).GetEvents(); foreach (EventInfo info in memberinfo) { //Console.WriteLine(info.Name); PropertyInfo propertyInfo = (typeof(System.Windows.Forms.Button)).GetProperty("Events", BindingFlags.Instance | BindingFlags.NonPublic); EventHandlerList eventHandlerList = (EventHandlerList)propertyInfo.GetValue(this.button2, null); FieldInfo fieldInfo = (typeof(Control).GetField("Event" + info.Name, BindingFlags.Static | BindingFlags.NonPublic)); if (fieldInfo != null) { Delegate d = eventHandlerList[fieldInfo.GetValue(null)]; if (d != null) { listBox1.Items.Add(d.Method.Name); } } }
出处：https://ask.csdn.net/questions/264615
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C#中移除自定义事件的所有方法
/// <summary> /// 移除一个对象指定事件的所有注册的方法 /// </summary> /// <typeparam name="T">泛型</typeparam> /// <param name="obj">当前对象</param> /// <param name="eventName">事件名</param> public static void RemoveEvent<T>(T obj, string eventName) { BindingFlags bindingFlags = BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Public | BindingFlags.Static; EventInfo[] eventInfo = obj.GetType().GetEvents(bindingFlags); if (eventInfo == null) { return; } foreach (EventInfo info in eventInfo) { if (string.Compare(info.Name, eventName, StringComparison.OrdinalIgnoreCase) == 0) { FieldInfo fieldInfo = info.DeclaringType.GetField(info.Name, bindingFlags); if (fieldInfo != null) { fieldInfo.SetValue(obj, null); } break; } } } //测试代码 PubFunction.RemoveEvent<BetchSettingValueForm>(this, "BeforeDictEntry"); //特殊帮助类型帮助前过滤扩展 MethodInfo method = valExtend.GetType().GetMethod(field.Element.LabelID + "_Extend"); if (method != null) { valExtend.gspState = GspState; valExtend.dsMXJH = MXJH; //转化method到delegate Delegate methodDel = PubFunction.CreateDelegateFromMethodInfo<BeforeDictEntryEventArgs<SmartHelpInfo>>(valExtend, method); //先移除事件再注册 BeforeDictEntry += methodDel as EventHandler<BeforeDictEntryEventArgs<SmartHelpInfo>>; } #endregion //值改变事件注册，完成批量设置 PubFunction.RemoveEvent<ButtonEdit>(helpEdit, "ButtonClick"); helpEdit.ButtonClick += helpEdit_ButtonClick;
出处：https://blog.csdn.net/soapcoder92/article/details/51027117
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Remove all the EventHandlers of the object by reflection
class Program { static void Main(string[] args) { Customer c = new Customer(); EventInfo evt = c.GetType().GetEvent("OnChange", BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Public ); // 添加一个事件关联 evt.AddEventHandler(c, new EventHandler(c_OnChange)); // 添加第二个事件关联 evt.AddEventHandler(c, new EventHandler(c_OnChange)); // 删除全部事件关联。 RemoveEvent<Customer>(c, "OnChange"); c.Change(); } static void c_OnChange(object sender, EventArgs e) { Console.WriteLine("事件被触发了"); } static void RemoveEvent<T>(T c, string name) { Delegate[] invokeList = GetObjectEventList(c, name); if (invokeList == null) return; foreach (Delegate del in invokeList) { typeof(T).GetEvent(name).RemoveEventHandler(c, del); } } public static Delegate[] GetObjectEventList(object p_Object, string p_EventName) { // Get event field FieldInfo _Field = p_Object.GetType().GetField(p_EventName, BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Public | BindingFlags.Static); if (_Field == null) { return null; } // get the value of event field which should be a delegate object _FieldValue = _Field.GetValue(p_Object); // if it is a delegate if (_FieldValue != null && _FieldValue is Delegate) { // cast the value to a delegate Delegate _ObjectDelegate = (Delegate)_FieldValue; // get the invocation list return _ObjectDelegate.GetInvocationList(); } return null; } } class Customer { public event EventHandler OnChange; public void Change() { if (OnChange != null) OnChange(this, null); else Console.WriteLine("no event attached"); } }
出处：https://blog.csdn.net/diandian82/article/details/5738299
参考：https://bbs.csdn.net/topics/370126564
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根据上面的代码，我自己经过修改如下：
/// <summary> /// 获取窗体控件的注册事件名称。 /// 例如：按钮的单击事件： /// GetObjectEventList<Control>(button1, "Click"); /// 菜单项的单击事件： /// GetObjectEventList<System.Windows.Forms.ToolStripItem>(menuStrip1.Items[0], "Click"); /// 不同的控件的基类也不相同，在使用的时候应格外注意，否则将返回Null /// 另外，我这里方法内部使用了EventClick的事件记录，在使用的时候最好还是调试看看事件名称是否匹配 /// </summary> /// <typeparam name="T">表示事件所定义的类</typeparam> /// <param name="pControl">控件实例，或事件的子类</param> /// <param name="pEventName">事件名称</param> /// <returns></returns> private Delegate[] GetObjectEventList<T>(T pControl, string pEventName) { Delegate[] ret = null; Type ctlType = typeof(T); PropertyInfo _PropertyInfo = ctlType.GetProperty("Events", BindingFlags.Instance | BindingFlags.NonPublic); if (_PropertyInfo != null) { EventHandlerList _EventList = _PropertyInfo.GetValue(pControl, null) as EventHandlerList; FieldInfo _FieldInfo = ctlType.GetField("Event" + pEventName, BindingFlags.Static | BindingFlags.NonPublic); if (_EventList != null && _EventList is EventHandlerList && _FieldInfo != null) { Delegate _ObjectDelegate = _EventList[_FieldInfo.GetValue(pControl)]; if (_ObjectDelegate != null) ret = _ObjectDelegate.GetInvocationList(); } } return ret; }
调用方式：（确定事件定义的类，如Button在Control中定义的Click事件，不然会找不到事件）
Delegate[] d1 = EventTest.GetObjectEventList<System.Windows.Forms.Control>(btnTest, "Click");
Delegate[] d2 = EventTest.GetObjectEventList<System.Windows.Forms.ToolStripItem>(menuStrip1.Items[0], "Click");
支持自定义类中的自定义事件
public static Delegate[] GetCustomEventList(object obj, string eventName) { Delegate[] ret = null; BindingFlags bindingFlags = BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Public | BindingFlags.Static; EventInfo[] eventInfo = obj.GetType().GetEvents(bindingFlags);//此处获取所有事件 EventInfo ei = obj.GetType().GetEvent(eventName, bindingFlags); if (ei != null) { FieldInfo _FieldInfo = ei.DeclaringType.GetField(eventName, bindingFlags); Delegate _ObjectDelegate = _FieldInfo.GetValue(obj) as Delegate; ret = _ObjectDelegate?.GetInvocationList(); } return ret; }