数据字典存储事件实例

      当有很多事件，大多数事件不会实现时，可以使用字典存储事件实例，这也是事件选择器的典型用法。

    public delegate void EventHandler1(int i);
    public delegate void EventHandler2(string s);

    public class PropertyEvent
    {
        Dictionary<string, System.Delegate> eventTable;

        public PropertyEvent()
        {
            eventTable = new Dictionary<string, Delegate>();
            eventTable.Add("Event1", null);
            eventTable.Add("Event2", null);
        }

        public event EventHandler1 Event1
        {
            add
            {
                lock (eventTable)
                {
                    eventTable["Event1"] = (EventHandler1)eventTable["Event1"] + value;
                }
            }
            remove
            {
                lock (eventTable)
                {
                    eventTable["Event1"] = (EventHandler1)eventTable["Event1"] - value;
                }
            }
        }

        public event EventHandler2 Event2
        {
            add
            {
                lock (eventTable)
                {
                    eventTable["Event2"] = (EventHandler2)eventTable["Event2"] + value;
                }
            }
            remove
            {
                lock (eventTable)
                {
                    eventTable["Event2"] = (EventHandler2)eventTable["Event2"] - value;
                }
            }
        }

        public void RaiseEvent1(int i)
        {
            EventHandler1 handler1 = (EventHandler1)eventTable["Event1"];
            if (handler1 != null)
                handler1(i);
        }

        public void RaiseEvent2(string s)
        {
            EventHandler2 handler2 = (EventHandler2)eventTable["Event2"];
            if (handler2 != null)
                handler2(s);
        }
    }

    class DictionaryEvent
    {
        public static void DelegateMethod1(int i)
        {
            Console.WriteLine(i.ToString());
        }
        public static void DelegateMethod2(string s)
        {
            Console.WriteLine(s);
        }
        public static void Main(string[] args)
        {
            PropertyEvent p = new PropertyEvent();

            p.Event1 += DictionaryEvent.DelegateMethod1;
            p.Event1 += DictionaryEvent.DelegateMethod1;
            p.Event1 += DictionaryEvent.DelegateMethod1;
            p.Event1 -= DictionaryEvent.DelegateMethod1;
            p.RaiseEvent1(1);

            p.Event2 += DictionaryEvent.DelegateMethod2;
            p.Event2 += DictionaryEvent.DelegateMethod2;
            p.Event2 += DictionaryEvent.DelegateMethod2;
            p.Event2 -= DictionaryEvent.DelegateMethod2;
            p.RaiseEvent2("Test");

            Console.Read();
        }
    }

输出如下：