using System;
using System.Collections.Generic;
using System.Text;



namespace 事件处理
{

    // Declare the delegate handler for the event:
    public delegate void MyEventHandler();

    class TestEvent
    {
        // Declare the event implemented by MyEventHandler.
        public event MyEventHandler TriggerIt;

        // Declare a method that triggers the event:
        public void Trigger()
        {
            TriggerIt();
        }
        // Declare the methods that will be associated with the TriggerIt event.
        public void MyMethod1()
        {
            System.Console.WriteLine("Hello!");
        }
        public void MyMethod2()
        {
            System.Console.WriteLine("Hello again!");
        }
        public void MyMethod3()
        {
            System.Console.WriteLine("Good-bye!");
        }

        static void Main()
        {
            // Create an instance of the TestEvent class.
            TestEvent myEvent = new TestEvent();

            // Subscribe to the event by associating the handlers with the events:
            myEvent.TriggerIt += new MyEventHandler(myEvent.MyMethod1);
            myEvent.TriggerIt += new MyEventHandler(myEvent.MyMethod2);
            myEvent.TriggerIt += new MyEventHandler(myEvent.MyMethod3);
            // Trigger the event:
            myEvent.Trigger();

            // Unsuscribe from the the event by removing the handler from the event:
            myEvent.TriggerIt -= new MyEventHandler(myEvent.MyMethod2);
            System.Console.WriteLine("\"Hello again!\" unsubscribed from the event.");

            // Trigger the new event:
            myEvent.Trigger();
            Console.ReadKey();
        }
    }

}

输出内容如下：

Hello!
Hello again!
Good-bye!
"Hello again!" unsubscribed from the event.
Hello!
Good-bye!

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