如何获得FutureTask在TimeoutException之后返回？

Z时代
2024-01-10
分类：问答

在下面的代码中，我按预期在100秒后捕获了TimeoutException。在这一点上，我希望代码从main退出，而程序终止，但它会一直打印到控制台。如何使任务在超时后停止执行？

private static final ExecutorService THREAD_POOL = Executors.newCachedThreadPool();
private static <T> T timedCall(Callable<T> c, long timeout, TimeUnit timeUnit) throws InterruptedException, ExecutionException, TimeoutException {
    FutureTask<T> task = new FutureTask<T>(c);
    THREAD_POOL.execute(task);
    return task.get(timeout, timeUnit);
}
public static void main(String[] args) {
    try {
        int returnCode = timedCall(new Callable<Integer>() {
            public Integer call() throws Exception {
                for (int i=0; i < 1000000; i++) {
                    System.out.println(new java.util.Date());
                    Thread.sleep(1000);
                }
                return 0;
            }
        }, 100, TimeUnit.SECONDS);
    } catch (Exception e) {
        e.printStackTrace();
        return;
    }
}

回答：

您需要在超时时取消任务（并中断其线程）。那就是cancel(true)方法。：

private static final ExecutorService THREAD_POOL = Executors.newCachedThreadPool();
private static <T> T timedCall(FutureTask<T> task, long timeout, TimeUnit timeUnit) throws InterruptedException, ExecutionException, TimeoutException {
    THREAD_POOL.execute(task);
    return task.get(timeout, timeUnit);
}
public static void main(String[] args) {
        try {
            FutureTask<Integer> task = new FutureTask<Integer>(new Callable<Integer>() {
                public Integer call() throws Exception {
                        for (int i=0; i < 1000000; i++) {
                                if (Thread.interrupted()) return 1;
                                System.out.println(new java.util.Date());
                                Thread.sleep(1000);
                        }
                        return 0;
                }
            });
            int returnCode = timedCall(task, 100, TimeUnit.SECONDS);
        } catch (Exception e) {
                e.printStackTrace();
                task.cancel(true);
        }
        return;
}