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();
    }
}