等待取消的未来实际完成

Question

我有一个SwingWorker调用一些不检查线程中断的代码.调用之后worker.cancel(true),该worker.get()方法将CancellationException立即抛出(正如它应该的那样).但是,由于后台任务的代码从不检查其线程是否被中断,因此它很乐意继续执行.

是否存在等待后台任务实际完成的标准方法？我希望显示一个"正在取消..."消息或类似的东西,并阻止任务终止.(我确信如果有必要,我可以在工人类中使用标志来完成此操作,只需查找其他任何解决方案.)

Answer 1

我对此进行了一些尝试，这就是我的想法。我正在使用 a CountDownLatch，并且基本上将其await()方法公开为我的对象上的方法SwingWorker。仍在寻找更好的解决方案。

final class Worker extends SwingWorker<Void, Void> {

    private final CountDownLatch actuallyFinishedLatch = new CountDownLatch(1);

    @Override
    protected Void doInBackground() throws Exception {
        try {
            System.out.println("Long Task Started");

            /* Simulate long running method */
            for (int i = 0; i < 1000000000; i++) {
                double d = Math.sqrt(i);
            }

            return null;
        } finally {
            actuallyFinishedLatch.countDown();
        }
    }

    public void awaitActualCompletion() throws InterruptedException {
        actuallyFinishedLatch.await();
    }

    public static void main(String[] args) {
        Worker worker = new Worker();
        worker.execute();

        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {

        }

        System.out.println("Cancelling");
        worker.cancel(true);

        try {
            worker.get();
        } catch (CancellationException e) {
            System.out.println("CancellationException properly thrown");
        } catch (InterruptedException e) {

        } catch (ExecutionException e) {

        }

        System.out.println("Awaiting Actual Completion");
        try {
            worker.awaitActualCompletion();
            System.out.println("Done");
        } catch (InterruptedException e) {

        }
    }

}