FutureTask 实现异步任务

FutureTask  的执行结果和出现异常的异常对象都会被放到outcome对象中，通过get()方法返回。

**1.测试future任务正常返回**

public class T2 {
    ThreadFactory namedThreadFactory = new ThreadFactoryBuilder().setNamePrefix("thread-start-runner").build();
    ExecutorService taskExe = new ThreadPoolExecutor(10, 20, 800L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>(100), namedThreadFactory);
    private static final Logger LOG = LoggerFactory.getLogger(T2.class);

    @Test
    public void test2() {
        List<FutureTask<Integer>> taskList = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            final int a = i;
            FutureTask<Integer> futureTask = new FutureTask<>(() -> {
                LOG.info("正在进行第" + a + "个任务");
                Thread.sleep(3000);
                return 1;
            });
            taskList.add(futureTask);
            //异步执行
            taskExe.submit(futureTask);
        }
        LOG.info("任务添加完成");
        int count = 0;
        try {
            for (FutureTask<Integer> task : taskList) {
                /*
                FutureTask执行的结果会放入它的私有变量outcome中，其他线程直接调用futureTask.get()去读取该变量即可
                会阻塞直到单个任务执行完毕
                * */
                Integer value = task.get();
                LOG.info("value:" + value);
                count += value;
            }
        } catch (InterruptedException e) {
            LOG.error("线程执行被中断", e);
        } catch (ExecutionException e) {
            LOG.error("线程执行出现异常", e);
        }
        taskExe.shutdown();
        LOG.info("count:" + count);

    }```


**2.测试future任务异常返回，通过get()方法拿到异常**

@Test
    public void test3() {
        List<FutureTask<Integer>> taskList = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            final int a = i;
            FutureTask<Integer> futureTask = new FutureTask<>(() -> {
                LOG.info("正在进行第" + a + "个任务");
                int v=1/0;
                return 1;
            });
            taskList.add(futureTask);
            //异步执行
            taskExe.submit(futureTask);
        }
        LOG.info("任务添加完成");
        int count = 0;
        try {
            for (FutureTask<Integer> task : taskList) {
                /*
                FutureTask执行的结果会放入它的私有变量outcome中（包括异常），其他线程直接调用futureTask.get()去读取该变量即可
                会阻塞直到单个任务执行完毕
                * */
                Integer value = task.get();
                LOG.info("value:" + value);
                count += value;
            }
        } catch (InterruptedException e) {
            LOG.error("线程执行被中断", e);
        } catch (ExecutionException e) {
            LOG.error("线程执行出现异常", e);
        }
        taskExe.shutdown();
        LOG.info("count:" + count);
}