C# 编程指南
如何：使用字典存储事件实例（C# 编程指南）
accessor-declarations 的一种用法是公开大量的事件但不为每个事件分配字段，而是使用字典来存储这些事件实例。这只有在具有非常多的事件、但您预计大部分事件都不会实现时才有用。
示例
C#
public delegate void EventHandler1(int i);
public delegate void EventHandler2(string s);
publicclass PropertyEventsSample
{
private System.Collections.Generic.Dictionary<string, System.Delegate> eventTable;
public PropertyEventsSample()
{
eventTable = new System.Collections.Generic.Dictionary<string, System.Delegate>();
eventTable.Add("Event1", null);
eventTable.Add("Event2", null);
}
public event EventHandler1 Event1
{
add
{
eventTable["Event1"] = (EventHandler1)eventTable["Event1"] + value;
}
remove
{
eventTable["Event1"] = (EventHandler1)eventTable["Event1"] - value;
}
}
public event EventHandler2 Event2
{
add
{
eventTable["Event2"] = (EventHandler2)eventTable["Event2"] + value;
}
remove
{
eventTable["Event2"] = (EventHandler2)eventTable["Event2"] - value;
}
}
internal void RaiseEvent1(int i)
{
EventHandler1 handler1;
if (null != (handler1 = (EventHandler1)eventTable["Event1"]))
{
handler1(i);
}
}
internal void RaiseEvent2(string s)
{
EventHandler2 handler2;
if (null != (handler2 = (EventHandler2)eventTable["Event2"]))
{
handler2(s);
}
}
}
publicclass TestClass
{
publicstaticvoid Delegate1Method(int i)
{
System.Console.WriteLine(i);
}
publicstaticvoid Delegate2Method(string s)
{
System.Console.WriteLine(s);
}
staticvoid Main()
{
PropertyEventsSample p = new PropertyEventsSample();
p.Event1 += new EventHandler1(TestClass.Delegate1Method);
p.Event1 += new EventHandler1(TestClass.Delegate1Method);
p.Event1 -= new EventHandler1(TestClass.Delegate1Method);
p.RaiseEvent1(2);
p.Event2 += new EventHandler2(TestClass.Delegate2Method);
p.Event2 += new EventHandler2(TestClass.Delegate2Method);
p.Event2 -= new EventHandler2(TestClass.Delegate2Method);
p.RaiseEvent2("TestString");
}
}
输出
2
TestString
(来源：msdn )