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我正在學習由Daniel M. Solis撰寫的Book Illustrated C#2010中的C#事件,並嘗試了關於VS 2010中事件的示例。出於某種原因,我收到了兩次事件消息,但對於我的生活,我無法弄清楚爲什麼。下面是代碼:爲什麼此事件發生兩次?
using System;
using System.Text;
using System.Threading;
namespace ConsoleApplication3
{
internal class MyTimerClass
{
public event EventHandler<MyTCEventArgs> Elapsed;
public void OnOneSecond(object source, EventArgs args)
{
if (Elapsed != null)
{
MyTCEventArgs mtcea = new MyTCEventArgs("Message from OnOneSecond");
Elapsed(source, mtcea);
}
}
//-----------------
private System.Timers.Timer MyPrivateTimer;
public MyTimerClass()
{
MyPrivateTimer = new System.Timers.Timer();
MyPrivateTimer.Elapsed += OnOneSecond;
MyPrivateTimer.Interval = 1000;
MyPrivateTimer.Enabled = true;
}
}
internal class ClassA
{
public void TimerHandlerA(object source, MyTCEventArgs args)
{
Console.WriteLine("Class A Message: {0}", args.Message);
}
}
internal class ClassB
{
public static void TimerHandlerB(object source, MyTCEventArgs args)
{
Console.WriteLine("Class B Message: {0}", args.Message);
}
}
internal class MyTCEventArgs : EventArgs
{
public string Message;
public MyTCEventArgs(string s)
{
Message = s;
}
}
internal class Program
{
private static void Main(string[] args)
{
ClassA ca = new ClassA();
MyTimerClass mc = new MyTimerClass();
mc.Elapsed += new EventHandler<MyTCEventArgs>(ca.TimerHandlerA);
mc.Elapsed += new EventHandler<MyTCEventArgs>(ClassB.TimerHandlerB);
Thread.Sleep(2250);
}
}
}
結果是以下消息: A類消息:從乙OnOneSecond 類消息的消息:從OnOneSecond A類消息的消息:從乙OnOneSecond 類消息消息:消息從OnOneSecond
爲什麼會發生兩次?另外還有一點,當我刪除Thread.Sleep行時,什麼也沒有發生。這也讓我感到困惑。
這很有道理。謝謝。我甚至沒有想到我的事件需要1秒才能真正被提出。 – JeramyRR 2012-04-07 01:42:59