线程池的实现原理

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

        if (corePoolSize < 0 ||  maximumPoolSize <= 0 ||  maximumPoolSize < corePoolSize || keepAliveTime < 0)
            throw new IllegalArgumentException();
        if (workQueue == null || threadFactory == null || handler == null)
            throw new NullPointerException();
       
        this.corePoolSize = corePoolSize;
        this.maximumPoolSize = maximumPoolSize;
        this.workQueue = workQueue;
        this.keepAliveTime = unit.toNanos(keepAliveTime);
        this.threadFactory = threadFactory;
        this.handler = handler;
    }