java计时器任务计划 [英] java timer task schedule

问题描述

从Stack Overflow上阅读我已经看到很多人不建议使用Timer Task。嗯...但我已经实现了这个：

From reading on Stack Overflow I've seen that many of you don't recommend using Timer Task. Hmmm... but I already implemented this:

我有这个代码：

detectionHandlerTimer.schedule(myTimerTask, 60 * 1000, 60 * 1000);

事情是myTimerTask的工作持续一段时间。

The thing is that work of myTimerTask lasts some time.

我想这样做：

1. 等待60秒。


2. 执行任务一段时间（例如40-100秒）。


3. 任务完成。


4. 等待60秒。


5. 做任务一段时间（例如40-100秒）。

1. wait 60 sec.
2. do task for some time (e.g. 40 - 100 sec).
3. task finished.
4. wait 60 seconds.
5. do task for some time (e.g. 40 - 100 sec).

但上面的代码表现得像这样

But the code above behaves like this

1. 等待60秒。


2. 执行任务一段时间（例如40 - 100秒）。


3. 任务完成


4. 执行任务一段时间（例如40 - 100秒）。

1. wait 60 sec.
2. do task for some time (e.g. 40 - 100 sec).
3. task finished
4. do task for some time (e.g. 40 - 100 sec).

由于任务的持续时间大于60，计时器在任务完成后立即启动任务。但我希望它再次等待。

Because the time duration of task is bigger than 60, timer starts task immediately after task is finished. But I would like it to wait again.

推荐答案

这样可行。关键是让任务本身（在完成之后）安排下一次出现的任务。

This works. The key is to have the task itself (after it completes) schedule the next occurrence of the task.

import java.util.Timer;
import java.util.TimerTask;

public class TaskManager {

    private Timer timer = new Timer();

    public static void main(String[] args) {
        TaskManager manager = new TaskManager();
        manager.startTask();
    }

    public void startTask() {
        timer.schedule(new PeriodicTask(), 0);
    }

    private class PeriodicTask extends TimerTask {
        @Override
        public void run() {
            System.out.println(System.currentTimeMillis() + " Running");

            /* replace with the actual task */
            try {
                Thread.sleep(15 * 1000);
            } catch(InterruptedException e) {
                e.printStackTrace();
            }
            /* end task processing */

            System.out.println(System.currentTimeMillis() + " Scheduling 10 seconds from now");
            timer.schedule(new PeriodicTask(), 10 * 1000);
        }
    }
}

打印：

$ javac TaskManager.java && java TaskManager
1288282514688 Running
1288282529711 Scheduling 10 seconds from now
1288282539712 Running
1288282554713 Scheduling 10 seconds from now
1288282564714 Running

如果你提取时间戳的第二个组成部分（为了清晰起见），这就是它的样子：

Here's what it looks like if you extract the second components of the timestamps (for clarity):

$ javac TaskManager.java && java TaskManager
14                                    Running
29 (+15 seconds execution)            Scheduling 10 seconds from now
39 (+10 seconds delay until next run) Running
54 (+15 seconds execution)            Scheduling 10 seconds from now
64 (+10 seconds delay until next run) Running

用 60 s替换 10 s。

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