多线程 线程池 ExecutorService

 package org.zln.thread;

 import java.util.Date;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;

 /**
  * Created by sherry on 000024/6/24 22:50.
  */
 public class TestExecutorService implements Runnable{
     public static void main(String[] args) {
         new Thread(new TestExecutorService()).start();
         System.out.println(new Date()+"主线程结束");
     }

     /*之所以将for循环写在一个run中，是为了防止线程池等待过程中造成的主线程堵塞*/
     @Override
     public void run() {
         /*创建一个大小为3的线程池*/
         ExecutorService executorService = Executors.newFixedThreadPool(3);
         for (int i = 0; i < 20; i++) {
             Runnable runnable = new Runnable() {
                 @Override
                 public void run() {
                     long time = (long)(Math.random()*1000);
                     System.out.println(new Date()+"休眠："+time+" 毫秒");
                     try {
                         Thread.sleep(time);
                     } catch (InterruptedException e) {
                         e.printStackTrace();
                     }
                 }
             };
             /*启动一个线程*/
             executorService.execute(runnable);
         }
         /*线程池必须使用shutdown显示关闭，否则当前线程无法退出*/
         executorService.shutdown();
     }
 }