Java并发-CycliBarrier

栅栏类似于闭锁，它能阻塞一组线程直到某个事件的发生。栅栏与闭锁的关键区别在于，所有的线程必须同时到达栅栏位置，才能继续执行。闭锁用于等待事件，而栅栏用于等待其他线程。
package com.example.demo.util.dxc;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.FutureTask;

/**
 * 测试CyclicBarrier 循环栅栏
 */
public class TestCycliBarrier {


    public void test() throws Exception {
        int threadNum = 10;
        Integer total = 0;
        CyclicBarrier cyclicBarrier1 = new CyclicBarrier(threadNum, new Runnable() {
            //最后一个线程到栅栏后要做的任务
            @Override
            public void run() {
                System.out.println("准备就绪,开始计算...");
            }
        });
        List<FutureTask<Integer>> list = new ArrayList<>();
        for (int j = 0; j < threadNum; j++) {
            FutureTask<Integer> future = new FutureTask<Integer>(new MyCallThread(cyclicBarrier1));
            Thread thread = new Thread(future);
            thread.start();
            list.add(future);
        }
        for (FutureTask<Integer> integerFutureTask : list) {
            total += integerFutureTask.get();
        }
        System.out.println("计算结果:" + total);
    }

    public static void main(String[] args) throws Exception {
        new TestCycliBarrier().test();
    }

}


package com.example.demo.util.dxc;

import java.util.concurrent.Callable;
import java.util.concurrent.CyclicBarrier;

public class MyCallThread implements Callable<Integer> {
    private CyclicBarrier cyclicBarrier;

    public MyCallThread(CyclicBarrier cyclicBarrier) {
        this.cyclicBarrier = cyclicBarrier;
    }

    @Override
    public Integer call() throws Exception {
        int num = 0;
        for (int i = 0; i <= 100; i++) {
            num += i;
        }
        System.out.println(Thread.currentThread().getName() + ":befor");
        //等待所有线程到达之后才会返回num
        cyclicBarrier.await();
        System.out.println(Thread.currentThread().getName() + ":after");
        return num;
    }
}