线程池创建的四种

通过Executors线程池创建的四种方法分别为：

newCachedThreadPool：创建一个可缓存线程池，如果线程池长度超过处理需要，可灵活回收空闲线程，若无可回收，则新建线程。

newFixedThreadPool：创建一个定长线程池，可控制线程最大并发数，超出的线程会在队列中等待。

newScheduledThreadPool：创建一个定长线程池，支持定时及周期性任务执行。

newSingleThreadExecutor：创建一个单线程化的线程池，它只会用唯一的工作线程来执行任务，保证所有任务按照指定顺序(FIFO, LIFO, 优先级)执行。

1. public class ThreadPoolExecutor extends AbstractExecutorService{//第一个构造方法public ThreadPoolExecutor(int corePoolSize,
2. int maximumPoolSize,
3. long keepAliveTime,
4. TimeUnit unit,
5. BlockingQueue<Runnable> workQueue) {
6. this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
7. Executors.defaultThreadFactory(), defaultHandler);
8. }//第二个构造方法public ThreadPoolExecutor(int corePoolSize,
9. int maximumPoolSize,
10. long keepAliveTime,
11. TimeUnit unit,
12. BlockingQueue<Runnable> workQueue,
13. ThreadFactory threadFactory) {
14. this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
15. threadFactory, defaultHandler);
16. }//第三个构造方法public ThreadPoolExecutor(int corePoolSize,
17. int maximumPoolSize,
18. long keepAliveTime,
19. TimeUnit unit,
20. BlockingQueue<Runnable> workQueue,
21. RejectedExecutionHandler handler) {
22. this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
23. Executors.defaultThreadFactory(), handler);
24. }//第四个也是真正的初始化构造函数public ThreadPoolExecutor(int corePoolSize,
25. int maximumPoolSize,
26. long keepAliveTime,
27. TimeUnit unit,
28. BlockingQueue<Runnable> workQueue,
29. ThreadFactory threadFactory,
30. RejectedExecutionHandler handler) {
31. if (corePoolSize < 0 ||
32. maximumPoolSize <= 0 ||
33. maximumPoolSize < corePoolSize ||
34. keepAliveTime < 0)
35. throw new IllegalArgumentException();
36. if (workQueue == null || threadFactory == null || handler == null)
37. throw new NullPointerException();
38. this.corePoolSize = corePoolSize;
39. this.maximumPoolSize = maximumPoolSize;
40. this.workQueue = workQueue;
41. this.keepAliveTime = unit.toNanos(keepAliveTime);
42. this.threadFactory = threadFactory;
43. this.handler = handler;
44. }}

其它答案

牛仔很忙2020-06-22 18:56:36

newCachedThreadPool创建可缓存线程池、newFixedThreadPool创建定长线程池、newScheduledThreadPool创建定长线程池、newSingleThreadExecutor创建单线程化线程池