11.2 Future&scheduleAtFixedRate与scheduleWithFixedDelay

demo:

public class ScheduledThreadPoolExecutorSample {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        //初始延迟执行线程池
        DateTimeFormatter timeFormatter = DateTimeFormatter.ofPattern("HH:mm:ss");
        System.out.println("1.start" + ",time:" + LocalDateTime.now().format(timeFormatter));
        ScheduledThreadPoolExecutor scheduledThreadPoolExecutor = new ScheduledThreadPoolExecutor(1);
        //普通的延迟执行
        scheduledThreadPoolExecutor.schedule(()->{
            System.out.println("延迟5秒执行。。。" + ",time:" + LocalDateTime.now().format(timeFormatter));
        },5000, TimeUnit.MILLISECONDS);
        //这里可以写主线程的业务,这里不会阻塞去等上面的延迟执行
        System.out.println("2.这里可以写主线程的业务,这里不会阻塞去等上面的5秒延迟执行" + ",time:" + LocalDateTime.now().format(timeFormatter));
        //也可以在延迟执行块里做一些逻辑任务,做完任务处理后并返回一个任务处理的结果值
        ScheduledFuture<Integer> future = scheduledThreadPoolExecutor.schedule(()->{
            System.out.println("延迟10秒执行。。。" + ",time:" + LocalDateTime.now().format(timeFormatter));
            return 1;
        },10000, TimeUnit.MILLISECONDS);
        //这里可以写主线程的业务,这里不会阻塞去等上面的延迟执行
        System.out.println("3.这里也可以写主线程的业务,这里不会阻塞去等上面的10延迟执行" + ",time:" + LocalDateTime.now().format(timeFormatter));
        //future.get()会阻塞线程,会在这里等结果再继续往下执行
        System.out.println("4.这里会阻塞等待future执行完返回结果再往下" + ",time:" + LocalDateTime.now().format(timeFormatter));
        System.out.println("5.future.get()执行任务返回结果值："+future.get() + ",time:" + LocalDateTime.now().format(timeFormatter));
        //周期性执行,如发送心跳,scheduleAtFixedRate是每间隔3秒就开始执行任务,并不管任务里是否已经完成了的,如果任务超过3秒才完成那就会堆积任务。
        scheduledThreadPoolExecutor.scheduleAtFixedRate(()->{
            System.out.println("周期性执行任务。。。" + ",time:" + LocalDateTime.now().format(timeFormatter));
        },5000,3000,TimeUnit.MILLISECONDS);
        System.out.println("6.这里也可以写主线程的业务,这里不会阻塞去等上面的周期性执行任务" + ",time:" + LocalDateTime.now().format(timeFormatter));
        //周期性执行,scheduleWithFixedDelay和scheduleAtFixedRate不同,scheduleWithFixedDelay是等任务执行完再间隔3秒才开始下一个任务
        scheduledThreadPoolExecutor.scheduleWithFixedDelay(()->{
            System.out.println("完成周期性任务间隔3秒后再继续执行新的周期性任务。。。" + ",time:" + LocalDateTime.now().format(timeFormatter));
        },5000,3000,TimeUnit.MILLISECONDS);
        System.out.println("7.这里也可以写主线程的业务,这里不会阻塞去等上面的周期性执行任务" + ",time:" + LocalDateTime.now().format(timeFormatter));
        System.out.println("8.end" + ",time:" + LocalDateTime.now().format(timeFormatter));
    }
}