AbstractExecutorService
DelegatedExecutorService
ScheduledThreadPoolExecutor
Executors
newFixedThreadPool()newFingleThreadPool()...
工厂类，用于产生各种不同类型的线程池
FinalizableDelegatedExecutorService
ThreadPoolExecutor
ExecutorService
submit(Runnable)submit(Callable)
ScheduledExecutorService
Executor
execute(Runnable)
