JAVA多线程—Executors类的应用

固定大小的线程池、缓存线程池、单一线程池

代码示例：

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

public class ThreadPoolTest {

    public static void main(String[] args) {
        ExecutorService threadPool = Executors.newFixedThreadPool(2);
        // ExecutorService threadPool = Executors.newCachedThreadPool();
        // ExecutorService threadPool = Executors.newSingleThreadExecutor();
        for (int i = 1; i <= 3; i++) {
            final int task = i;
            threadPool.execute(new Runnable() {
                @Override
                public void run() {
                    for (int j = 1; j <= 3; j++) {
                        try {
                            Thread.sleep(20);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        System.out.println(Thread.currentThread().getName() + " is looping of " + j + " for  task of " + task);
                    }
                }
            });
        }
        System.out.println("all of 10 tasks have committed! ");
        threadPool.shutdown();
    }
}

三个线程池的运行结果如下：

ExecutorService threadPool = Executors.newFixedThreadPool(2);

注意：如果没有threadPool.shutdown();这行代码的话，程序将一直处于等待状态，即红圈处一直变红。

ExecutorService threadPool = Executors.newCachedThreadPool();

ExecutorService threadPool = Executors.newSingleThreadExecutor();

线程池启动定时器示例

调用ScheduledExecutorService的schedule方法，返回的ScheduleFuture对象可以取消任务。

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class ThreadPoolTest {

    public static void main(String[] args) {

        Executors.newScheduledThreadPool(3).scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");

                System.out.println("当前时间：" + sdf.format(new Date()) + " bombing!");
            }
        }, 0, 2, TimeUnit.SECONDS);
    }
}

运行结果：