线程池

public ThreadPoolExecutor(int corePoolSize, //线程数，相当于银行的开放的窗口数
                          int maximumPoolSize,// 最大的线程数，相当于银行可以开放的最多的窗口数
                          long keepAliveTime,// 多余的空闲线程存活的时间
                          TimeUnit unit,// 空闲的线程可以存活的时间
                          BlockingQueue<Runnable> workQueue)// 阻塞队列，相当于银行的等候大厅

 {
    this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
         Executors.defaultThreadFactory(), defaultHandler);
}

public ThreadPoolExecutor(int corePoolSize,//线程数，相当于银行的开放的窗口数
                          int maximumPoolSize, //最大的线程数，相当于银行可以开放的最多的窗口数
                          long keepAliveTime, //多余的空闲线程存活的时间
                          TimeUnit unit, //空闲的线程可以存活的时间
                          BlockingQueue<Runnable> workQueue, //阻塞队列，相当于银行的等候大厅
                          ThreadFactory threadFactory, //线程工厂，一般用默认的方式，相当于银行的ID标识
                          RejectedExecutionHandler handler) //拒绝策略，有四种拒绝方法

{
    if (corePoolSize < 0 ||
        maximumPoolSize <= 0 ||
        maximumPoolSize < corePoolSize ||
        keepAliveTime < 0)
        throw new IllegalArgumentException();
    if (workQueue == null || threadFactory == null || handler == null)
        throw new NullPointerException();
    this.acc = System.getSecurityManager() == null ?
            null :
            AccessController.getContext();
    this.corePoolSize = corePoolSize;
    this.maximumPoolSize = maximumPoolSize;
    this.workQueue = workQueue;
    this.keepAliveTime = unit.toNanos(keepAliveTime);
    this.threadFactory = threadFactory;
    this.handler = handler;
}