ThreadPoolExecutor(int corePoolSize, 
int maximumPoolSize, 
long keepAliveTime, 
TimeUnit unit, 
BlockingQueue<Runnable> workQueue, 
ThreadFactory threadFactory, 
RejectedExecutionHandler handler)

public class 線程池 {
    public static void main(String[] args) {
        // 創(chuàng)建一個(gè)固定線程數(shù)目的線程池. 參數(shù)指定了線程個(gè)數(shù)
        ExecutorService pool = Executors.newFixedThreadPool(10);

        //創(chuàng)建一個(gè)自動(dòng)擴(kuò)容的線程池，會(huì)根據(jù)任務(wù)量來(lái)進(jìn)行自動(dòng)擴(kuò)容
        Executors.newCachedThreadPool();

        //創(chuàng)建一個(gè)只有一個(gè)線程的線程池
        Executors.newSingleThreadExecutor();

        //創(chuàng)建一個(gè)帶有定時(shí)器功能的線程池，類似于Timer
        Executors.newScheduledThreadPool(10);

        for (int i = 0; i < 100; i++) {
            pool.submit(new Runnable() {
                @Override
                public void run() {
                    System.out.println("hello threadpool");
                }
            });
        }

    }
}

class MyThreadPool{
    //1.先描述一個(gè)任務(wù)，直接使用Runnable不需要產(chǎn)生額外類
    //2.使用一個(gè)數(shù)據(jù)結(jié)構(gòu)來(lái)組織若干任務(wù)
        private BlockingQueue<Runnable> queue= new LinkedBlockingDeque<>();
    //3.描述一個(gè)線程，工作線程的功能就是從任務(wù)隊(duì)列中取任務(wù)并執(zhí)行
    static class Worker extends Thread{
        //當(dāng)前線程池中有若干個(gè)Worker線程，這些線程內(nèi)部都持有了上述的任務(wù)隊(duì)列
        private BlockingQueue<Runnable> queue = null;
        public Worker(BlockingQueue<Runnable> queue){
            this.queue = queue;
        }

        @Override
        public void run() {
            //就需要能夠拿到上面的隊(duì)列
            while(true){

                try {
                    //循環(huán)的去獲取任務(wù)隊(duì)列中的人物
                    //這里如果隊(duì)列為空就直接阻塞，如果隊(duì)列非空就獲取到里面的內(nèi)容
                    Runnable runnable = queue.take();
                    //獲取到后就執(zhí)行
                    runnable.run();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    //4.創(chuàng)建一個(gè)數(shù)據(jù)結(jié)構(gòu)來(lái)組織若干個(gè)線程
    private List<Thread> workers = new ArrayList<>();
    public MyThreadPool(int n){
        //在構(gòu)造方法中創(chuàng)建若干個(gè)線程放到上述數(shù)組中
        for (int i = 0; i < n; i++) {
            Worker worker = new Worker(queue);
            worker.start();
            workers.add(worker);
        }
    }

    //5.創(chuàng)建一個(gè)方法，能夠允許程序員來(lái)放任務(wù)到線程池中
    public void submit(Runnable runnable){
        try {
            queue.put(runnable);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}
public class 我的線程池 {
    public static void main(String[] args) {
        MyThreadPool pool = new MyThreadPool(10);
        for (int i = 0; i < 100; i++) {
            pool.submit(new Runnable() {
                @Override
                public void run() {
                    System.out.println("hello threadpool");
                }
            });
        }
    }
}