package com.basic; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.Semaphore; /** * @program JavaBooks * @description: Semaphore例子 * @author: mf * @create: 2020/01/09 15:35 */ public class T32 { // 请求的数量 private static final int threadCount = 20; public static void main(String[] args) { ExecutorService service = Executors.newFixedThreadPool(10); // 一次只能允许执行的线程数量 final Semaphore semaphore = new Semaphore(5); for (int i = 0; i < threadCount; i++) { final int threadNum = i; service.execute(() -> { try { semaphore.acquire(); // 获取一个许可，所以可运行线程数量为5/1=5 Thread.sleep(1000); System.out.println("threadNum: " + threadNum); Thread.sleep(1000); semaphore.release(); // 释放一个许可 } catch (InterruptedException e) { e.printStackTrace(); } }); } service.shutdown(); System.out.println("finish..."); } }