Java：如何实现代码超时功能？

Question

public static void function() {

    // 代码1

    // 代码2

    // 代码3

}

如果代码2执行时间过长则不再执行（代码2没有抛出TimeoutException，只是没按照规定时间执行完），继续执行后面的代码3该如何实现呢？

下面是代码超时功能的一种实现

   public class Timeout {

    public static void main(String[] args) throws InterruptedException, ExecutionException {

        ExecutorService exec = Executors.newFixedThreadPool(1);

        Callable<Integer> call = new Callable<Integer>() {

            public Integer call() throws Exception {

                Thread.sleep(1000 * 5);// 耗时操作

                return 1;

            }

        };

        try {

            Future<Integer> future = exec.submit(call);

            int ret = future.get(1000 * 1, TimeUnit.MILLISECONDS); // 任务处理超时时间设为 1 秒

            System.out.println("任务执行结果：" + ret);

        } catch (TimeoutException e) {

            e.printStackTrace();

        } catch (Exception e) {

            e.printStackTrace();

        }

        exec.shutdown();

    }

}

但这种方法的问题是新启动了一个线程，并没有阻塞，也就是我的代码3可能先于Timeout执行完，顺序不满足预期，前辈有什么好办法呢？

Answer 1

写了个小例子，可以简单实现你的要求import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.TimeUnit;public class Main {&nbsp; &nbsp; public static void main(String[] args) throws InterruptedException {&nbsp; &nbsp; &nbsp; &nbsp; ExecutorService es = Executors.newFixedThreadPool(1);&nbsp; &nbsp; &nbsp; &nbsp; es.execute(new Runnable() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; @Override&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public void run() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; int count = 7;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; while (count > 0) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println(1);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; try {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Thread.sleep(1000);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; } catch (InterruptedException e) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // 退出执行&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println("interrupt, then quit");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; count--;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; });&nbsp; &nbsp; &nbsp; &nbsp; // 关闭线程池&nbsp; &nbsp; &nbsp; &nbsp; es.shutdown();&nbsp; &nbsp; &nbsp; &nbsp; // 阻塞操作，等待5s&nbsp; &nbsp; &nbsp; &nbsp; boolean finished = es.awaitTermination(5, TimeUnit.SECONDS);&nbsp; &nbsp; &nbsp; &nbsp; // 如果过了5s线程还没有完成, 强制关闭, interrupt Runnable 线程,&nbsp; 进入 InterruptedException 处理流程&nbsp; &nbsp; &nbsp; &nbsp; if (!finished) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; es.shutdownNow();&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; System.out.println("task 3");&nbsp; &nbsp; }}