如何向 C# 控制台应用程序添加计时器

Question

仅此而已 - 如何向 C# 控制台应用程序添加计时器？ 如果您能提供一些示例编码，那就太好了。

Answer 1

这很好，但是为了模拟一些时间的流逝，我们需要运行一个需要一些时间的命令，这在第二个示例中非常清楚。

然而，使用 for 循环来执行某些功能的风格永远需要大量的设备资源，而我们可以使用垃圾收集器来做一些类似的事情。

我们可以在同一本书 CLR Via C# Third Ed 的代码中看到这种修改。

using System;
using System.Threading;

public static class Program 
{
   private Timer _timer = null;
   public static void Main() 
   {
      // Create a Timer object that knows to call our TimerCallback
      // method once every 2000 milliseconds.
      _timer = new Timer(TimerCallback, null, 0, 2000);
      // Wait for the user to hit <Enter>
      Console.ReadLine();
   }

   private static void TimerCallback(Object o) 
   {
      // Display the date/time when this method got called.
      Console.WriteLine("In TimerCallback: " + DateTime.Now);
   }
}

Answer 2

使用 System.Threading.Timer 类。

System.Windows.Forms.Timer 主要设计用于单线程，通常是 Windows 窗体 UI 线程。

还有一个 System.Timers 类是在 .NET 框架开发的早期添加的。 然而，通常建议使用 System.Threading.Timer 类，因为这只是 System.Threading.Timer 的包装器。

如果您正在开发 Windows 服务并需要计时器定期运行，还建议始终使用静态（在 VB.NET 中共享）System.Threading.Timer。 这将避免您的计时器对象可能过早的垃圾收集。

以下是控制台应用程序中的计时器示例：

using System; 
using System.Threading; 
public static class Program 
{ 
    public static void Main() 
    { 
       Console.WriteLine("Main thread: starting a timer"); 
       Timer t = new Timer(ComputeBoundOp, 5, 0, 2000); 
       Console.WriteLine("Main thread: Doing other work here...");
       Thread.Sleep(10000); // Simulating other work (10 seconds)
       t.Dispose(); // Cancel the timer now
    }
    // This method's signature must match the TimerCallback delegate
    private static void ComputeBoundOp(Object state) 
    { 
       // This method is executed by a thread pool thread 
       Console.WriteLine("In ComputeBoundOp: state={0}", state); 
       Thread.Sleep(1000); // Simulates other work (1 second)
       // When this method returns, the thread goes back 
       // to the pool and waits for another task 
    }
}

来自 Jeff Richter 的CLR Via C#一书。 顺便说一下，本书在第 23 章中描述了 3 种定时器背后的基本原理，强烈推荐。

Answer 3

这是创建一个简单的一秒计时器滴答的代码：

  using System;
  using System.Threading;

  class TimerExample
  {
      static public void Tick(Object stateInfo)
      {
          Console.WriteLine("Tick: {0}", DateTime.Now.ToString("h:mm:ss"));
      }

      static void Main()
      {
          TimerCallback callback = new TimerCallback(Tick);

          Console.WriteLine("Creating timer: {0}\n", 
                             DateTime.Now.ToString("h:mm:ss"));

          // create a one second timer tick
          Timer stateTimer = new Timer(callback, null, 0, 1000);

          // loop here forever
          for (; ; )
          {
              // add a sleep for 100 mSec to reduce CPU usage
              Thread.Sleep(100);
          }
      }
  }

这是结果输出：

    c:\temp>timer.exe
    Creating timer: 5:22:40

    Tick: 5:22:40
    Tick: 5:22:41
    Tick: 5:22:42
    Tick: 5:22:43
    Tick: 5:22:44
    Tick: 5:22:45
    Tick: 5:22:46
    Tick: 5:22:47

编辑：将硬自旋循环添加到代码中绝不是一个好主意，因为它们会消耗 CPU 周期而没有任何收益。 在这种情况下，添加循环只是为了阻止应用程序关闭，从而允许观察线程的操作。 但是为了正确性和减少 CPU 使用率，在该循环中添加了一个简单的 Sleep 调用。

Answer 4

让我们玩得开心

using System;
using System.Timers;

namespace TimerExample
{
    class Program
    {
        static Timer timer = new Timer(1000);
        static int i = 10;

        static void Main(string[] args)
        {            
            timer.Elapsed+=timer_Elapsed;
            timer.Start(); Console.Read();
        }

        private static void timer_Elapsed(object sender, ElapsedEventArgs e)
        {
            i--;

            Console.Clear();
            Console.WriteLine("=================================================");
            Console.WriteLine("                  DEFUSE THE BOMB");
            Console.WriteLine(""); 
            Console.WriteLine("                Time Remaining:  " + i.ToString());
            Console.WriteLine("");        
            Console.WriteLine("=================================================");

            if (i == 0) 
            {
                Console.Clear();
                Console.WriteLine("");
                Console.WriteLine("==============================================");
                Console.WriteLine("         B O O O O O M M M M M ! ! ! !");
                Console.WriteLine("");
                Console.WriteLine("               G A M E  O V E R");
                Console.WriteLine("==============================================");

                timer.Close();
                timer.Dispose();
            }

            GC.Collect();
        }
    }
}

Answer 5

或者使用 Rx，简短而甜蜜：

static void Main()
{
Observable.Interval(TimeSpan.FromSeconds(10)).Subscribe(t => Console.WriteLine("I am called... {0}", t));

for (; ; ) { }
}

Answer 6

如果您想要更多的控制，您也可以使用自己的计时机制，但可能会降低准确性和更多代码/复杂性，但我仍然建议使用计时器。 如果您需要控制实际的计时线程，请使用它：

private void ThreadLoop(object callback)
{
    while(true)
    {
        ((Delegate) callback).DynamicInvoke(null);
        Thread.Sleep(5000);
    }
}

将是您的计时线程（修改它以在需要时停止，并且在您想要的任何时间间隔内停止）。

并使用/启动您可以执行以下操作：

Thread t = new Thread(new ParameterizedThreadStart(ThreadLoop));

t.Start((Action)CallBack);

回调是您想要在每个时间间隔调用的 void 无参数方法。 例如：

private void CallBack()
{
    //Do Something.
}

Answer 7

在 C# 5.0+ 和 .NET Framework 4.5+ 中，您可以使用 async/await：

async void RunMethodEvery(Action method, double seconds)
{
    while (true)
    {
        await Task.Delay(TimeSpan.FromSeconds(seconds));
        method();
    }
 }

Answer 8

您也可以创建自己的（如果对可用选项不满意）。

创建自己的Timer实现是非常基本的东西。

这是一个应用程序的示例，该应用程序需要在与我的代码库的其余部分相同的线程上访问 COM 对象。

/// <summary>
/// Internal timer for window.setTimeout() and window.setInterval().
/// This is to ensure that async calls always run on the same thread.
/// </summary>
public class Timer : IDisposable {

    public void Tick()
    {
        if (Enabled && Environment.TickCount >= nextTick)
        {
            Callback.Invoke(this, null);
            nextTick = Environment.TickCount + Interval;
        }
    }

    private int nextTick = 0;

    public void Start()
    {
        this.Enabled = true;
        Interval = interval;
    }

    public void Stop()
    {
        this.Enabled = false;
    }

    public event EventHandler Callback;

    public bool Enabled = false;

    private int interval = 1000;

    public int Interval
    {
        get { return interval; }
        set { interval = value; nextTick = Environment.TickCount + interval; }
    }

    public void Dispose()
    {
        this.Callback = null;
        this.Stop();
    }

}

您可以按如下方式添加事件：

Timer timer = new Timer();
timer.Callback += delegate
{
    if (once) { timer.Enabled = false; }
    Callback.execute(callbackId, args);
};
timer.Enabled = true;
timer.Interval = ms;
timer.Start();
Window.timers.Add(Environment.TickCount, timer);

为了确保计时器正常工作，您需要创建一个无限循环，如下所示：

while (true) {
     // Create a new list in case a new timer
     // is added/removed during a callback.
     foreach (Timer timer in new List<Timer>(timers.Values))
     {
         timer.Tick();
     }
}

Answer 9

文档

你有它 ：）

public static void Main()
   {
      SetTimer();

      Console.WriteLine("\nPress the Enter key to exit the application...\n");
      Console.WriteLine("The application started at {0:HH:mm:ss.fff}", DateTime.Now);
      Console.ReadLine();
      aTimer.Stop();
      aTimer.Dispose();

      Console.WriteLine("Terminating the application...");
   }

   private static void SetTimer()
   {
        // Create a timer with a two second interval.
        aTimer = new System.Timers.Timer(2000);
        // Hook up the Elapsed event for the timer. 
        aTimer.Elapsed += OnTimedEvent;
        aTimer.AutoReset = true;
        aTimer.Enabled = true;
    }

    private static void OnTimedEvent(Object source, ElapsedEventArgs e)
    {
        Console.WriteLine("The Elapsed event was raised at {0:HH:mm:ss.fff}",
                          e.SignalTime);
    }

Answer 10

我建议您遵循 Microsoft 指南（ https://docs.microsoft.com/en-us/dotnet/api/system.timers.timer.interval?view=netcore-3.1 ）。

我首先尝试使用System.Threading; 和

var myTimer = new Timer((e) =>
{
   // Code
}, null, TimeSpan.Zero, TimeSpan.FromSeconds(5));

但它在大约 20 分钟后不断停止。

有了这个，我尝试了解决方案设置

GC.KeepAlive(myTimer)

要么

for (; ; ) { }
}

但它们在我的情况下不起作用。

按照 Microsoft 文档，它运行良好：

using System;
using System.Timers;

public class Example
{
    private static Timer aTimer;

    public static void Main()
    {
        // Create a timer and set a two second interval.
        aTimer = new System.Timers.Timer();
        aTimer.Interval = 2000;

        // Hook up the Elapsed event for the timer. 
        aTimer.Elapsed += OnTimedEvent;

        // Have the timer fire repeated events (true is the default)
        aTimer.AutoReset = true;

        // Start the timer
        aTimer.Enabled = true;

        Console.WriteLine("Press the Enter key to exit the program at any time... ");
        Console.ReadLine();
    }

    private static void OnTimedEvent(Object source, System.Timers.ElapsedEventArgs e)
    {
        Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime);
    }
}
// The example displays output like the following: 
//       Press the Enter key to exit the program at any time... 
//       The Elapsed event was raised at 5/20/2015 8:48:58 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:00 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:02 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:04 PM 
//       The Elapsed event was raised at 5/20/2015 8:49:06 PM 

Answer 11

使用 Github 上的 PowerConsole 项目https://github.com/bigabdoul/PowerConsole或等效的 NuGet 包https://www.nuget.org/packages/PowerConsole 。 它以可重用的方式优雅地处理计时器。 看看这个示例代码：

using PowerConsole;

namespace PowerConsoleTest
{
    class Program
    {
        static readonly SmartConsole MyConsole = SmartConsole.Default;

        static void Main()
        {
            RunTimers();
        }

        public static void RunTimers()
        {
            // CAUTION: SmartConsole is not thread safe!
            // Spawn multiple timers carefully when accessing
            // simultaneously members of the SmartConsole class.

            MyConsole.WriteInfo("\nWelcome to the Timers demo!\n")

            // SetTimeout is called only once after the provided delay and
            // is automatically removed by the TimerManager class
            .SetTimeout(e =>
            {
                // this action is called back after 5.5 seconds; the name
                // of the timer is useful should we want to clear it
                // before this action gets executed
                e.Console.Write("\n").WriteError("Time out occured after 5.5 seconds! " +
                    "Timer has been automatically disposed.\n");

                // the next statement will make the current instance of 
                // SmartConsole throw an exception on the next prompt attempt
                // e.Console.CancelRequested = true;

                // use 5500 or any other value not multiple of 1000 to 
                // reduce write collision risk with the next timer
            }, millisecondsDelay: 5500, name: "SampleTimeout")

            .SetInterval(e =>
            {
                if (e.Ticks == 1)
                {
                    e.Console.WriteLine();
                }

                e.Console.Write($"\rFirst timer tick: ", System.ConsoleColor.White)
                .WriteInfo(e.TicksToSecondsElapsed());

                if (e.Ticks > 4)
                {
                    // we could remove the previous timeout:
                    // e.Console.ClearTimeout("SampleTimeout");
                }

            }, millisecondsInterval: 1000, "EverySecond")

            // we can add as many timers as we want (or the computer's resources permit)
            .SetInterval(e =>
            {
                if (e.Ticks == 1 || e.Ticks == 3) // 1.5 or 4.5 seconds to avoid write collision
                {
                    e.Console.WriteSuccess("\nSecond timer is active...\n");
                }
                else if (e.Ticks == 5)
                {
                    e.Console.WriteWarning("\nSecond timer is disposing...\n");

                    // doesn't dispose the timer
                    // e.Timer.Stop();

                    // clean up if we no longer need it
                    e.DisposeTimer();
                }
                else
                {
                    System.Diagnostics.Trace.WriteLine($"Second timer tick: {e.Ticks}");
                }
            }, 1500)
            .Prompt("\nPress Enter to stop the timers: ")
            
            // makes sure that any remaining timer is disposed off
            .ClearTimers()

            .WriteSuccess("Timers cleared!\n");
        }
    }
}