如何判断控件的事件是否存在

使用示例

var isBind = IsBindEvent(comboBox.GetType(), comboBox, "comboBox_TextChanged");

if (!isBind)

{

comboBox.TextChanged += comboBox_TextChanged;

}

//是否已经绑定了事件
private bool IsBindEvent(Type type, Control con, string eventName)
{
bool isBind = false;

PropertyInfo pi = type.GetProperty("Events", BindingFlags.Instance | BindingFlags.NonPublic);   //获取type类定义的所有事件的信息
EventHandlerList ehl = (EventHandlerList)pi.GetValue(con, null);    //获取con对象的事件处理程序列表
FieldInfo fieldInfo = (typeof(Control)).GetField("EventText", BindingFlags.Static | BindingFlags.NonPublic); //获取Control类Click事件的字段信息
Delegate d = ehl[fieldInfo.GetValue(null)];
if (d == null)
{
return isBind;
}
foreach (Delegate del in d.GetInvocationList())
{
if (del.Method.Name == eventName)
{
isBind = true;
break;
}
}
return isBind;
}