{"type":"doc","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"之前寫了線程和鎖，例子中採用直接創建線程的方式，這種方式做示例可以，但在實際生產環境中比較少用，通常會使用線程池。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"使用線程池有一些明顯的好處，可以考慮我們使用連接池的情形，不難想像。使用線程池可以免去我們手動創建和銷燬線程的工作，節省這部分資源的消耗，提高響應速度，同時線程由線程池維護，也提高了線程的可管理性。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"JDK中默認實現了多種線程池，如FixedThreadPool，SingleThreadExecutor，CachedThreadPool，ScheduledThreadPool，SingleThreadScheduledExecutor，WorkStealingPool。ForkJoinPool也是線程池的一種，通常我們單獨討論，之前的文章有所介紹。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"線程工廠"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"線程池的創建方法使用線程池的工廠類Executors，調用相應的方法創建相應的線程池。創建線程池的工作即實例化ThreadPoolExecutor，所以有必要簡單看下ThreadPoolExecutor。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"ThreadPoolExecutor的構造參數："}]},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"/**\n* Creates a new {@code ThreadPoolExecutor} with the given initial\n* parameters.\n*\n* @param corePoolSize the number of threads to keep in the pool, even\n* if they are idle, unless {@code allowCoreThreadTimeOut} is set\n* @param maximumPoolSize the maximum number of threads to allow in the\n* pool\n* @param keepAliveTime when the number of threads is greater than\n* the core, this is the maximum time that excess idle threads\n* will wait for new tasks before terminating.\n* @param unit the time unit for the {@code keepAliveTime} argument\n* @param workQueue the queue to use for holding tasks before they are\n* executed. This queue will hold only the {@code Runnable}\n* tasks submitted by the {@code execute} method.\n* @param threadFactory the factory to use when the executor\n* creates a new thread\n* @param handler the handler to use when execution is blocked\n* because the thread bounds and queue capacities are reached\n* @throws IllegalArgumentException if one of the following holds:\n* {@code corePoolSize < 0}
\n* {@code keepAliveTime < 0}
\n* {@code maximumPoolSize <= 0}
\n* {@code maximumPoolSize < corePoolSize}\n* @throws NullPointerException if {@code workQueue}\n* or {@code threadFactory} or {@code handler} is null\n*/\npublic ThreadPoolExecutor(int corePoolSize,\n int maximumPoolSize,\n long keepAliveTime,\n TimeUnit unit,\n BlockingQueue