java - Thread.sleep 在循环中调用 - 在这种情况下如何防止它(通过重构)？

Question

我在 NetBeans 中面临以下警告:

我知道这是人们面临的一个常见问题，我在发帖前阅读了一些相关问题。但在这种特定情况下——我正在做 exponential backoff使用 Jsoup 下载文档 - 我不确定如何防止警告。我想到了一个时间递增的计时器，但是...这是最优雅的方式吗？

Document downloadPageAsDocument(String url) throws IOException {
    long waitTime = MILLIS_PER_SECOND;
    while (waitTime < MILLIS_PER_HOUR) {
        try {
            return Jsoup.connect(url).timeout(REQ_TIMEOUT_MILLISECONDS).get(); // an IOException is thrown on timeout by Jsoup
        } catch (IOException ex) {
            log.log(Level.WARNING, "{0}... wating {1} seconds", new Object[]{ex.getMessage(), (waitTime / MILLIS_PER_SECOND)});
            try {
                Thread.sleep(waitTime);
            } catch (InterruptedException ex1) {
            }
            waitTime *= 2;
        }
    }
    throw new IOException("I quited after " + (waitTime / MILLIS_PER_SECOND) + " seconds");
}

Answer 1

虽然 Thread.sleep() 很少是一个好的解决方案，但我认为您的情况是一个异常(exception)，因为它使您的意图明确。所以，我会采纳@user1274820 的建议来添加一个@SuppressWarnings。但是，这是我在不使用 Thread.sleep()

的情况下执行此操作的方法

static ScheduledExecutorService exec = Executors.newScheduledThreadPool(1);

Document downloadPageAsDocument(String url) throws IOException {
    AtomicLong waitTime = new AtomicLong(MILLIS_PER_SECOND);
    try {
        while (waitTime.get() < MILLIS_PER_HOUR) {
            System.out.println("iteration wait=" + waitTime.get());
            ScheduledFuture<String> future = exec.schedule(() -> {
                try {
                    return jsoupCall();
                } catch (IOException ex) {
                    waitTime.getAndUpdate((l) -> l * 2);
                }
                return null;
            }, waitTime.get(), TimeUnit.MILLISECONDS);
            if (future.get() != null) { // wait for completion
                break; //break if jsoupCall was successful
            }
        }
    } catch (InterruptedException | ExecutionException e) {
        // handle exceptions
    }
}