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) > -)
{
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.****.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.****.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) == )
{
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.****.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.****.net/diandian82/article/details/5738299
参考：https://bbs.****.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;
}