设计一个限流器：大厂面试题

import com.google.common.util.concurrent.RateLimiter;
import com.google.common.util.concurrent.ThreadFactoryBuilder;

import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicLong;


/**
 * @author Administrator
 * 简单实现一个限流器
 * Guava 是谷歌开源的工具类库，它提供了RateLimiter作为限流工具类，使用前需要引入它的依赖如下。
 */
public class TestLimiter {
    public static void main(String[] args) throws InterruptedException {
        TestLimiter testLimiter = new TestLimiter();
        testLimiter.method();
    }
    public void method() throws InterruptedException {
//        定义限流器流速：1个请求/秒（1s/请求）
        RateLimiter rateLimiter = RateLimiter.create(1);
        //给线程池命名
        ThreadFactory threadName = new ThreadFactoryBuilder().setNameFormat("ThreadPool-%d").build();
        // 创建执行任务的线程池
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(5, 10,
                1000, TimeUnit.MINUTES, new LinkedBlockingQueue<>(20), threadName, new ThreadPoolExecutor.AbortPolicy());
        //可获取当前时间
        AtomicLong preTime = new AtomicLong(System.nanoTime());
        for (int i = 0; i < 20; i++) {
            //限流器限流
            rateLimiter.acquire();
            //线程开始执行，上面是搞得1秒一个请求
            threadPoolExecutor.execute(()->{
                long nanoTime = System.nanoTime();
                System.out.println("nanoTime-preTime = " + (nanoTime - preTime.get())/1000_000+"   线程"+Thread.currentThread().getName());
                preTime.set(nanoTime);
            });
        }
        //设置线程关闭
        threadPoolExecutor.shutdown();
        //关闭等待时间
        threadPoolExecutor.awaitTermination(2000,TimeUnit.MINUTES);
    }
}