多线程编程之ThreadPoolExecutor

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尽管面临很多挑战，多线程有一些优点使得它一直被使用。这些优点是：

• 资源利用率更好
• 程序设计在某些情况下更简单
• 程序响应更快；

比如我们在批量操作数据时候，采用多线程往往可以节省成倍的时间；提高了系统资源利用率；

import java.util.concurrent.*;

public class TestThred {

    public static void main(String[] args) {

//        ThreadPoolExecutor executor = new ThreadPoolExecutor(5, 10, 200, TimeUnit.MILLISECONDS,
//                new ArrayBlockingQueue<Runnable>(0));

        ExecutorService  executor = Executors.newCachedThreadPool();



        for (int i = 0; i < 20; i++) {
            MyTask myTask = new MyTask(i);
            executor.execute(myTask);
//            System.out.println("线程池中线程数目：" + executor.getPoolSize() + "，队列中等待执行的任务数目：" +
//                    executor.getQueue().size() + "，已执行玩别的任务数目：" + executor.getCompletedTaskCount());
        }
        executor.shutdown();
    }
}

class MyTask implements Runnable {
    private int taskNum;

    public MyTask(int num) {
        this.taskNum = num;
    }

    @Override
    public void run() {
        System.out.println("正在执行task " + taskNum);
        try {
            Thread.currentThread().sleep(4000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("task " + taskNum + "执行完毕");
    }
}