@RestController
@RequestMapping("/test/")
public class TestController {

    @GetMapping("supply")
    @ResponseBody
    public Integer supply() throws ExecutionException, InterruptedException {
        List<CompletableFuture<Integer>> list = new ArrayList<>();

        for (int i = 1; i < 6; i++) {

            int finalI = i;
            CompletableFuture<Integer> integerCompletableFuture = CompletableFuture.supplyAsync(() -> {
                try {
                    Thread.sleep(finalI * 2000);
                    System.out.println(Thread.currentThread().getName());
                } catch (InterruptedException e) {
                    return finalI;
                }
                return finalI;
            });

            list.add(integerCompletableFuture);
        }

        Integer i = 0;
        for (CompletableFuture<Integer> integerCompletableFuture : list) {
            if (i >= 2) {
                boolean cancel = integerCompletableFuture.cancel(true);
                System.out.println(cancel);
            }else {
                i += integerCompletableFuture.get();
            }
        }
        System.out.println(i);
        return i;
    }
}

这是上面这段代码的执行结果:

ForkJoinPool.commonPool-worker-1
ForkJoinPool.commonPool-worker-2
ForkJoinPool.commonPool-worker-3
true
true
true
3
ForkJoinPool.commonPool-worker-4
ForkJoinPool.commonPool-worker-1
ForkJoinPool.commonPool-worker-5

老师，这个我很疑惑，明明已经取消了3个线程执行，cancle方法也返回了3次true，为啥之后被取消的线程 还继续执行。。打印出来线程名称。