模仿CyclicBarrier，自定义自己屏障类

package com.jacky;

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

/**
 * Created by jacky on 2018/2/11.
 */
public class MyCyclicBarrier {
    private int count;
    private int parties;
    private  Runnable barrierAction;

    private final ReentrantLock lock = new ReentrantLock();

    private final Condition condition = lock.newCondition();


    public MyCyclicBarrier(int parties,Runnable barrierAction){
        if (parties <=0){
            throw new IllegalArgumentException();
        }
        this.parties = parties;
        this.count = parties;
        this.barrierAction = barrierAction;
    }
    public  int await() throws InterruptedException,BrokenBarrierException {
        lock.lock();
        try {
            int index = --count;
            if (index ==0){
              if (null == barrierAction){
                  barrierAction.run();
              }
                condition.signalAll();
               return  index;
            }
            for (;;){
                 condition.await();
                return index;
            }
        }finally {
            lock.unlock();
        }
    }
}

package com.jacky;

import com.sun.org.apache.xpath.internal.SourceTree;

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;

/**
 * Created by jacky on 2018/2/11.
 */
public class CyclicBarrierDemo {
    public static void main(String[] args) throws InterruptedException {
        MyCyclicBarrier barrier = new MyCyclicBarrier(3, new Runnable() {
            @Override
            public void run() {
                Thread thread = Thread.currentThread();
                System.out.println("barrierAction start"+thread.getName());
                try {
                    Thread.sleep((int)Math.random()*300);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("barrierAction start"+thread.getName());
            }
        });
        Runnable runnable1 = new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep((int)(Math.random()*100));
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Thread thread = Thread.currentThread();
                System.out.println("thread start:"+thread.getName());
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                try {
                    barrier.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
                System.out.println("thread end:"+thread.getName());
            }
        };
        Runnable runnable2 = new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep((int)(Math.random()*200));
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Thread thread = Thread.currentThread();
                System.out.println("thread start:"+thread.getName());
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                try {
                    barrier.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
                System.out.println("thread end:"+thread.getName());
            }
        };
        Thread thread1 = new Thread(runnable1);
        Thread thread2 = new Thread(runnable2);
        Thread thread3 = new Thread(runnable1);
        thread1.start();
        thread2.start();
        thread3.start();
        Thread.sleep(2000);
        System.out.println("thread1:"+thread1.getName()+","+thread1.getState());
        System.out.println("thread2:"+thread2.getName()+","+thread2.getState());
        System.out.println("thread3:"+thread3.getName()+","+thread3.getState());
    }
}