public class WorkQueue{
    private final int nThreads;
    private final PoolWorker[] threads;
    private final LinkedList queue;
    public WorkQueue(int nThreads) {
        this.nThreads = nThreads;
        queue = new LinkedList();
        threads = new PoolWorker[nThreads];
        for (int i=0; i<nThreads; i++) {
            threads[i] = new PoolWorker();
            threads[i].start();
        }
    }
    public void execute(Runnable r) { // 你用此函数来提交任务
        synchronized(queue) {
            queue.addLast(r);
            queue.notify();
        }
    }
    private class PoolWorker extends Thread { // 这是线程池中的工作线程
        public void run() {
            Runnable r;
            while (true) { // 死循环，工作线程永远在工作
                synchronized(queue) {
                    while (queue.isEmpty()) { // 从队列中获取任务，直到获取到任务
                        try {
                            queue.wait();
                        }
                        catch (InterruptedException ignored){
                        }
                    }
                    r = (Runnable) queue.removeFirst(); // 取出该任务
                }
                // If we don't catch RuntimeException, 
                // the pool could leak threads
                try {
                    r.run(); // 执行该任务
                }
                catch (RuntimeException e) {
                    // You might want to log something here
                }
            }
        }
    }
}