ThreadPoolExecutor 创建线程池

 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)