countDownLatch简单使用测试

CountDownLatch使用场景

线程计数器 用于线程执行任务,计数 等待线程结束

测试代码:

@Log4j2
public class CountDownLatchController {
    public static void main(String[] args) {
        //线程数10
        ExecutorService threadPool = Executors.newFixedThreadPool(10);
        try {
            //获取数量5
            List ids = getMap();
            //赋值CountDownLatch线程计数5
            CountDownLatch countDownLatch = new CountDownLatch(ids.size());
            DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
            for (String id : ids) {
                //异步处理
                threadPool.submit(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            System.out.println("id = "+id + "时间 = "+df.format(LocalDateTime.now(ZoneOffset.of("+8"))) + " 线程 = "+Thread.currentThread().getName());
                            Thread.sleep(2000);
                        } catch (Exception e) {
                            e.printStackTrace();
                        }finally {
                            //线程计数减1
                            countDownLatch.countDown();
                        }
                    }
                });
            }
            //等待线程计算为0  或者 等待一分钟还不为0则不等待了
            countDownLatch.await(1,TimeUnit.MINUTES);
            System.out.println("我是小张啊 " + "时间 = "+df.format(LocalDateTime.now(ZoneOffset.of("+8"))) + " 线程 = "+Thread.currentThread().getName());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            //关闭线程池
            threadPool.shutdown();
        }
    }

    public static List getMap(){
        List ids = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            ids.add(i+"");
        }
        return ids;
    }

}

 测试结果: