多线程编程学习九(并发工具类).，

多线程编程学习九(并发工具类).，

CountDownLatch

public class CountDownLatchTest {

    private static final CountDownLatch DOWN_LATCH = new CountDownLatch(2);

    public static void main(String[] args) throws InterruptedException {
        new Thread(() -> {
            System.out.println(1);
            DOWN_LATCH.countDown();
            System.out.println(2);
            DOWN_LATCH.countDown();

        }).start();
        DOWN_LATCH.await();
        System.out.println("3");
    }
}

CyclicBarrier

public class BankWaterService implements Runnable {
 
    // 创建4个屏障，处理完之后执行当前类的run方法
    private CyclicBarrier barrier = new CyclicBarrier(4, this);
    // 假设有4个计算任务，所以只启动4个线程
    private Executor executor = Executors.newFixedThreadPool(4);
    // 保存每个任务的计算结果
    private ConcurrentHashMap<String, Integer> sheetBankWaterCount = new ConcurrentHashMap<>();

    private AtomicInteger atomicInteger = new AtomicInteger(1);

    private void count() {
        for (int i = 0; i < 4; i++) {
            Thread thread = new Thread(() -> {
                // 当前任务的计算结果，计算过程忽略
                sheetBankWaterCount.put(Thread.currentThread().getName(), 1);
                // 计算完成，插入一个屏障
                try {
                    barrier.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }

            }, "线程" + atomicInteger.getAndIncrement());
            executor.execute(thread);
        }
    }

    @Override
    public void run() {
        int result = 0;
        // 汇总每个任务计算出的结果
        for (Map.Entry<String, Integer> sheet : sheetBankWaterCount.entrySet()) {
            result += sheet.getValue();
        }
        //将结果输出
        sheetBankWaterCount.put("result", result);
        System.out.println(result);
    }

    public static void main(String[] args) {
        BankWaterService bankWaterCount = new BankWaterService();
        bankWaterCount.count();
    }
}

Semaphore

public class SemaphoreTest {

    private static final int THREAD_COUNT = 30;
    private static ExecutorService EXECUTOR = Executors.newFixedThreadPool(THREAD_COUNT);
    private static Semaphore SEMAPHORE = new Semaphore(10);
    private static AtomicInteger ATOMICINTEGER = new AtomicInteger(1);

    public static void main(String[] args) {
        for (int i = 0; i < THREAD_COUNT; i++) {
            EXECUTOR.execute(() -> {
                try {
                    SEMAPHORE.acquire();
                    System.out.println("save data" + ATOMICINTEGER.getAndIncrement());
                    SEMAPHORE.release();
                } catch (InterruptedException e) {
                }

            });
        }
        EXECUTOR.shutdown();
    }
}

Exchanger

public class ExchangerTest {

    private static final Exchanger<String> exchange = new Exchanger<>();
    private static ExecutorService threadPool = Executors.newFixedThreadPool(2);

    public static void main(String[] args) {
        threadPool.execute(() -> {
            try {
                String result = exchange.exchange("数据A");
                System.out.println("A的exchange结果：" + result);
            } catch (InterruptedException e) {
            }

        });
        threadPool.execute(() -> {
            try {
                String result = exchange.exchange("数据B");
                System.out.println("B的exchange结果：" + result);
            } catch (InterruptedException e) {
            }
        });
        threadPool.shutdown();
    }
}