异步&线程池 线程池的七大参数 初始化线程的4种方式 【上篇】

Executors.newFiexedThreadPool(3);
//或者
new ThreadPoolExecutor(corePoolSize, maximumPoolSize, keepAliveTime, TimeUnit unit, workQueue, threadFactory, handler);

public class ThreadTestDemo {
    public static void main(String[] args) {
        System.out.println("main.....start......");
        Thread01 thread01 = new Thread01();
        thread01.start(); //启动线程
        System.out.println("main.....end......");

    }

    public static class Thread01 extends Thread{
        @Override
        public void run() {
            System.out.println("当前线程是："+Thread.currentThread().getId());
            int i = 8 / 2;
            System.out.println("运算结果是："+i);
        }
    }
}

public class ThreadTestDemo {
    public static void main(String[] args) {
        System.out.println("main.....start......");
        Runnable01 runnable01 = new Runnable01();
        new Thread(runnable01).start();
        System.out.println("main.....end......");

    }

    /**
     * 实现 Runnable 接口
     */
    public static class Runnable01 implements Runnable{
        @Override
        public void run() {
            System.out.println("当前线程是："+Thread.currentThread().getId());
            int i = 10 / 2;
            System.out.println("运算结果是："+i);
        }
    }
}

public class ThreadTestDemo {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        System.out.println("main.....start......");
        FutureTask<Integer> futureTask = new FutureTask<>(new Callable01());
        new Thread(futureTask).start();
        //阻塞等待整个线程执行完成，获取返回结果
        Integer integer = futureTask.get();
        System.out.println("获取到的线程返回结果是："+integer);
        System.out.println("main.....end......");

    }

    /**
     * 实现 Callable 接口 + FutureTask （可以拿到返回结果，可以处理异常）
     */
    public static class Callable01 implements Callable<Integer>{
        @Override
        public Integer call() throws Exception {
            System.out.println("当前线程是："+Thread.currentThread().getId());
            int i = 12 / 2;
            System.out.println("运算结果是："+i);
            return i;
        }
    }
}

public class ThreadTestDemo {
    public static ExecutorService executor = Executors.newFixedThreadPool(10);

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        System.out.println("main.....start......");
        //提交给线程池去执行
        executor.execute(new Runnable01());
        System.out.println("main.....end......");

    }


    /**
     * 实现 Runnable 接口
     */
    public static class Runnable01 implements Runnable{
        @Override
        public void run() {
            System.out.println("当前线程是："+Thread.currentThread().getId());
            int i = 10 / 2;
            System.out.println("运算结果是："+i);
        }
    }


}

* @param corePoolSize the number of threads to keep in the pool, even
* if they are idle, unless {@code allowCoreThreadTimeOut} is set
池中一直保持的线程的数量，即使线程空闲。除非设置了 allowCoreThreadTimeOut
* @param maximumPoolSize the maximum number of threads to allow in the
* pool
池中允许的最大的线程数
* @param keepAliveTime when the number of threads is greater than
* the core, this is the maximum time that excess idle threads
* will wait for new tasks before terminating. 当线程数大于核心线程数的时候，线程在最大多长时间没有接到新任务就会终止释放，
最终线程池维持在 corePoolSize 大小
* @param unit the time unit for the {@code keepAliveTime} argument
时间单位
* @param workQueue the queue to use for holding tasks before they are
* executed. This queue will hold only the {@code Runnable}
* tasks submitted by the {@code execute} method. 阻塞队列，用来存储等待执行的任务，如果当前对线程的需求超过了 corePoolSize
大小，就会放在这里等待空闲线程执行。
* @param threadFactory the factory to use when the executor
* creates a new thread
创建线程的工厂，比如指定线程名等
* @param handler the handler to use when execution is blocked
* because the thread bounds and queue capacities are reached
拒绝策略，如果线程满了，线程池就会使用拒绝策略。