JUC 之定时器 Timer 无限期重复执行任务

1. 指定间隔周期无限循环执行

Timer.schedule(TimerTask task, long delay, long period) 源码

public class Timer {
    /**
     * task – task to be scheduled.
     * delay – delay in milliseconds before task is to be executed.
     * period – time in milliseconds between successive task executions.
     */
    public void schedule(TimerTask task, long delay, long period) {
        if (delay < 0)
            throw new IllegalArgumentException("Negative delay.");
        if (period <= 0)
            throw new IllegalArgumentException("Non-positive period.");
        sched(task, System.currentTimeMillis()+delay, -period);
    }
}

2. 例程

/**
 * 按指定的间隔周期无限循环地执行某一任务
 */
@Test
public void periodSchedule() throws Exception {
    log.info("开始时间：" + System.currentTimeMillis());
    Timer timer = new Timer();
    timer.schedule(new TimerTask() {
        @Override
        public void run() {
            log.info("任务执行：" + System.currentTimeMillis());
        }
    }, 3000, 2000);

    TimeUnit.SECONDS.sleep(Integer.MAX_VALUE);
}

打印结果：

15:09:52.098 [main] INFO juc.TimerDemo - 开始时间：1699168192094
15:09:55.116 [Timer-0] INFO juc.TimerDemo - 任务执行：1699168195116
15:09:57.108 [Timer-0] INFO juc.TimerDemo - 任务执行：1699168197108
15:09:59.108 [Timer-0] INFO juc.TimerDemo - 任务执行：1699168199108