Java并发包线程池ThreadPoolExecutor的实现

private final AtomicInteger ctl = new AtomicInteger(ctlOf(RUNNING, 0));
private static final int COUNT_BITS = Integer.SIZE - 3;
private static final int CAPACITY   = (1 << COUNT_BITS) - 1;

// runState is stored in the high-order bits
private static final int RUNNING    = -1 << COUNT_BITS;
private static final int SHUTDOWN   =  0 << COUNT_BITS;
private static final int STOP       =  1 << COUNT_BITS;
private static final int TIDYING    =  2 << COUNT_BITS;
private static final int TERMINATED =  3 << COUNT_BITS;

public class MyRunnable implements Runnable {
    @Override
    public void run() {
        System.out.println("我要一个教练");
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("教练来了： " + Thread.currentThread().getName());
        System.out.println("教我游泳,交完后，教练回到了游泳池");
    }
}

public class ThreadPoolDemo {
    public static void main(String[] args) {
        // 创建线程池对象
        ExecutorService service = Executors.newFixedThreadPool(2);//包含2个线程对象
        // 创建Runnable实例对象
        MyRunnable r = new MyRunnable();

        //自己创建线程对象的方式
        // Thread t = new Thread(r);
        // t.start(); ---> 调用MyRunnable中的run()

        // 从线程池中获取线程对象,然后调用MyRunnable中的run()
        service.submit(r);
        // 再获取个线程对象，调用MyRunnable中的run()
        service.submit(r);
        service.submit(r);
        // 注意：submit方法调用结束后，程序并不终止，是因为线程池控制了线程的关闭。
        // 将使用完的线程又归还到了线程池中
        // 关闭线程池
        //service.shutdown();
    }
}

public class ThreadPoolDemo2 {
    public static void main(String[] args) throws Exception {
        // 创建线程池对象
      ExecutorService service = Executors.newFixedThreadPool(2);//包含2个线程对象

        // 创建Runnable实例对象
        Callable<Double> c = new Callable<Double>() {
            @Override
            public Double call() throws Exception {
                return Math.random();
            }
        };

        // 从线程池中获取线程对象,然后调用Callable中的call()
        Future<Double> f1 = service.submit(c);
        // Futur 调用get() 获取运算结果
        System.out.println(f1.get());

        Future<Double> f2 = service.submit(c);
        System.out.println(f2.get());

        Future<Double> f3 = service.submit(c);
        System.out.println(f3.get());
    }
}

public class Demo04 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService pool = Executors.newFixedThreadPool(3);

        SumCallable sc = new SumCallable(100);
        Future<Integer> fu = pool.submit(sc);
        Integer integer = fu.get();
        System.out.println("结果: " + integer);
        
        SumCallable sc2 = new SumCallable(200);
        Future<Integer> fu2 = pool.submit(sc2);
        Integer integer2 = fu2.get();
        System.out.println("结果: " + integer2);

        pool.shutdown();
    }
}

public class SumCallable implements Callable<Integer> {
    private int n;

    public SumCallable(int n) {
        this.n = n;
    }

    @Override
    public Integer call() throws Exception {
        // 求1-n的和?
        int sum = 0;
        for (int i = 1; i <= n; i++) {
            sum += i;
        }
        return sum;
    }
}