java 线程篇之 Executor、ExecutorService、ThreadPoolExecutor、ScheduledThreadPoolExecutor-优快云博客

本文详细介绍了Java中线程池的使用方法，包括Executor、ExecutorService、ThreadPoolExecutor和ScheduledThreadPoolExecutor等核心接口与类的功能及应用场景。通过示例代码展示了如何配置线程池参数、提交任务、批量处理任务及实现定时任务。

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1、Executor

顶层接口，只提供

void execute(Runnable command); //提供执行线程启动线程方法

2、ExecutorService

提供了

shutdown() , 阻止提交新任务

shutdownNow(),阻止提交新任务，并且终止当前所有遗留的任务

awaitTermination(long timeout, TimeUnit unit) //阻塞，等到超时，或者中断执行，一般配合shutdown使用

shutdown的使用例子

public class ExecutorServiceTest {

    private static int count = 0;
    private static final ExecutorService excutor = new ThreadPoolExecutor(3,10,1L, TimeUnit.SECONDS,new ArrayBlockingQueue<Runnable>(10));
    private static final ReentrantLock lock = new ReentrantLock();
    private static final CountDownLatch start = new CountDownLatch(1);
    private static final CountDownLatch end = new CountDownLatch(10);

    public static void main(String[] args) throws InterruptedException {
        for (int i=0; i<3 ;i++){
            Thread thread = new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        start.await();
                        end.countDown();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }


                    lock.lock();
                    try {
                        count = count +1;
                        System.out.println("执行数量..."+count);
                    }catch (Exception e){
                        e.printStackTrace();
                    }finally {
                        lock.unlock();
                    }
                }
            });
            excutor.submit(thread);
        }

        excutor.shutdown();

        Thread thread1 = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("=====");
            }
        });

        try {
            excutor.submit(thread1);
        }catch (Exception e){
            System.out.println("提交任务失败");
        }

        start.countDown();
        end.await();
    }




}

submit(Callable<T>task),提交任务，有返回值，比如

public static void main(String[] args) throws ExecutionException, InterruptedException {

    CallAbleTask callAbleTask = new CallAbleTask();
    Future <String> future = excutor.submit(callAbleTask);

    System.out.println(future.get()); //阻塞等待返回
}

private static class CallAbleTask implements Callable<String> {

    @Override
    public String call() throws Exception {
        Thread.sleep(6000L);

        return "异步处理";
    }
}

submit(Runable task ) 把任务丢到线程池中执行，又线程池管理任务

invokeAll(Collection<? extends Callable<T>> tasks) //批处理任务，返回值放到一个Future集合中

public static void main(String[] args) throws ExecutionException, InterruptedException {

    List<CallAbleTask> list = new ArrayList<>();
    CallAbleTask callAbleTask = new CallAbleTask();
    CallAbleTask callAbleTask1 = new CallAbleTask();
    list.add(callAbleTask);
    list.add(callAbleTask1);
    List<Future<String>> futures = excutor.invokeAll(list);

    for(Future future:futures)
        System.out.println(future.get());
}

private static class CallAbleTask implements Callable<String> {

    @Override
    public String call() throws Exception {
        Thread.sleep(2000L);
        return "异步处理";
    }
}

3、ThreadPoolExecutor

线程池提供了管理线程的一组方案，比如

public void setKeepAliveTime(long time, TimeUnit unit) //设置空闲线程最大的存活时间

public boolean remove(Runnable task) //从线程池中移除任务

public void purge() //清空队列中的任务

4、ScheduledThreadPoolExecutor

这个类主要是提供一种延迟队列创建线程池的方法，当然可以直接通过ThreadPoolExecutor创建

比如创建一个延迟队列的线程池，1s后才执行任务

private static final ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(1);
public static void main(String[] args) {
    executor.schedule(new Runnable() {
        @Override
        public void run() {
            System.out.println("==============");
        }
    },1L,TimeUnit.SECONDS);

}

转载于:https://my.oschina.net/chenping12/blog/1517616