08-JUC--并发流程

1.什么是控制并发流程

2.CountDownLatch

CountDownLatch的作用

CountDownLatch的主要方法

/**
 * @Classname CountDownLatchDemo01
 * @Description 工厂中，质检，5个工人，所有人都认为通过，才通过。
 * @Date 2021/2/26 14:55
 * @Created by YoungLiu
 */
public class CountDownLatchDemo01 {
    
    
    public static void main(String[] args) throws InterruptedException {
    
    
        CountDownLatch countDownLatch = new CountDownLatch(5);
        ExecutorService service = Executors.newFixedThreadPool(5);
        for (int i = 0; i < 5; i++) {
    
    
            final int no =i+1;
            Runnable runnable = new Runnable() {
    
    

                @Override
                public void run() {
    
    
                    try {
    
    
                        Thread.sleep((long) (Math.random() * 10000));
                        System.out.println("No." + no + " 完成了检查");
                    } catch (InterruptedException e) {
    
    
                        e.printStackTrace();
                    } finally {
    
    
                        countDownLatch.countDown();
                    }
                }
            };
            service.submit(runnable);
        }

        System.out.println("等待5个人的检查....");
        countDownLatch.await();
        System.out.println("检查完毕");
    }
}

3.Semaphore

主要方法介绍

注意点

4. Condition接口（条件对象）

4.1 作用

4.2 代码演示

/**
 * @Classname ConditionDemo01
 * @Description 演示condition基本用法
 * @Date 2021/2/26 15:51
 * @Created by YoungLiu
 */
public class ConditionDemo01 {
    
    
    private ReentrantLock lock  = new ReentrantLock();
    private Condition condition =  lock.newCondition();

    void method1(){
    
    
        lock.lock();
        try{
    
    
            System.out.println("条件不满足，开始await");
            condition.await();
            System.out.println("条件满足了，开始执行后续任务");
        } catch (InterruptedException e) {
    
    
            e.printStackTrace();
        } finally {
    
    
            lock.unlock();
        }
    }

    void method2(){
    
    
        lock.lock();
        try{
    
    
            System.out.println("准备工作完成，开始唤醒其他的线程");
            condition.signal();
        }finally {
    
    
            lock.unlock();
        }
    }

    public static void main(String[] args) {
    
    
        ConditionDemo01 conditionDemo01 = new ConditionDemo01();

        new Thread(new Runnable() {
    
    
            @Override
            public void run() {
    
    
                try {
    
    
                    Thread.sleep(1000);
                    conditionDemo01.method2();
                } catch (InterruptedException e) {
    
    
                    e.printStackTrace();
                }

            }
        }).start();
        conditionDemo01.method1();
        
    }
}

4.3 注意点

5.CyclicBarrier

/**
 * @Classname CyclibarrierDemo
 * @Description TODO
 * @Date 2021/2/26 16:22
 * @Created by YoungLiu
 */
public class CyclibarrierDemo01 {
    
    
    public static void main(String[] args) {
    
    
        CyclicBarrier cyclicBarrier = new CyclicBarrier(5, new Runnable() {
    
    
            @Override
            public void run() {
    
    
                System.out.println("所有人都到场了，大家统一出发");
            }
        });
        for (int i = 0; i < 5; i++) {
    
    
            new Thread(new Task(i,cyclicBarrier)).start();
        }
    }

    static class Task implements Runnable{
    
    
        private int id;
        private CyclicBarrier cyclicBarrier;

        public Task(int id,CyclicBarrier cyclicBarrier){
    
    
            this.id = id;
            this.cyclicBarrier=cyclicBarrier;
        }

        @Override
        public void run() {
    
    
            System.out.println("线程 "+ id + "现在前往集合地铁");
            try {
    
    
                Thread.sleep((long)(Math.random()*10000));
                System.out.println("线程 "+ id + "到了集合地点，开始等待其他人到达");
                cyclicBarrier.await();
            } catch (InterruptedException | BrokenBarrierException e) {
    
    
                e.printStackTrace();
            }
        }
    }
}