``` java.util.concurrent.ThreadPoolExecutor 有4個構造方法,選取最多參數的那個來講解 ``` **構造方法:** ``` public ThreadPoolExecutor( int corePoolSize, //核心線程池大小 int maximumPoolSize, //最大線程池大小 long keepAliveTime, //線程最大空閑時間 TimeUnit unit, //時間單位 BlockingQueue<Runnable> workQueue, //線程等等隊列 ThreadFactory threadFactory, //線程創建工廠 RejectedExecutionHandler handler //拒絕策略 ) ``` **預定義線程池:** ``` ExecutorService newFixedThreadPool = Executors.newFixedThreadPool(1); ExecutorService newCachedThreadPool = Executors.newCachedThreadPool(); ExecutorService newSingleThreadExecutor = Executors.newSingleThreadExecutor(); ScheduledExecutorService scheduledExecutorService = Executors.newScheduledThreadPool(1); ```