其实spring-context整个调度模块完全依赖于TaskScheduler实现，更底层的是JUC调度线程池ScheduledThreadPoolExecutor。如果想要从底层原理理解整个调度模块的运行原理，那么就一定要分析ScheduledThreadPoolExecutor的实现。整篇文章大致介绍了spring-context调度模块的加载调度任务的流程，并且基于扩展接口SchedulingConfigurer扩展出多种自定义配置调度任务的方式，但是考虑到需要在生产环境中运行，那么免不了需要考虑监控、并发控制、日志跟踪等等的功能，但是这样就会使得整个调度模块变重，慢慢地就会发现，这个轮子越造越大，越有主流调度框架Quartz或者Easy Scheduler的影子。笔者认为，软件工程，有些时候要权衡取舍，该抛弃的就应该果断抛弃，否则总是负重而行，还能走多远？
参考资料：
SpringBoot源码
附录ScheduleTaskAssistant：
@RequiredArgsConstructor @Component public class ScheduleTaskAssistant { /** * 5秒 */ public static final long DEFAULT_WAIT_TIME = 5L; /** * 30秒 */ public static final long DEFAULT_LEAVE_TIME = 30L; private final DistributedLockFactory distributedLockFactory; /** * 在分布式锁中执行 * * @param waitTime 锁等着时间 * @param leaveTime 锁持有时间 * @param timeUnit 时间单位 * @param lockKey 锁的key * @param task 任务对象 */ public void executeInDistributedLock(long waitTime, long leaveTime, TimeUnit timeUnit, String lockKey, Runnable task) { DistributedLock lock = distributedLockFactory.dl(lockKey); boolean tryLock = lock.tryLock(waitTime, leaveTime, timeUnit); if (tryLock) { try { long waitTimeMillis = timeUnit.toMillis(waitTime); long start = System.currentTimeMillis(); task.run(); long end = System.currentTimeMillis(); long cost = end - start; // 预防锁过早释放 if (cost < waitTimeMillis) { Sleeper.X.sleep(waitTimeMillis - cost); } } finally { lock.unlock(); } } } /** * 在分布式锁中执行 - 使用默认时间 * * @param lockKey 锁的key * @param task 任务对象 */ public void executeInDistributedLock(String lockKey, Runnable task) { executeInDistributedLock(DEFAULT_WAIT_TIME, DEFAULT_LEAVE_TIME, TimeUnit.SECONDS, lockKey, task); } }RedissonDistributedLock：
@Slf4j public class RedissonDistributedLock implements DistributedLock { private final RedissonClient redissonClient; private final String lockPath; private final RLock internalLock; RedissonDistributedLock(RedissonClient redissonClient, String lockPath) { this.redissonClient = redissonClient; this.lockPath = lockPath; this.internalLock = initInternalLock(); } private RLock initInternalLock() { return redissonClient.getLock(lockPath); } @Override public boolean isLock() { return internalLock.isLocked(); } @Override public boolean isHeldByCurrentThread() { return internalLock.isHeldByCurrentThread(); } @Override public void lock(long leaseTime, TimeUnit unit) { internalLock.lock(leaseTime, unit); } @Override public boolean tryLock(long waitTime, long leaseTime, TimeUnit unit) { try { return internalLock.tryLock(waitTime, leaseTime, unit); } catch (InterruptedException e) { Thread.currentThread().interrupt(); throw new IllegalStateException(String.format("Acquire lock fail by thread interrupted,path:%s", lockPath), e); } } @Override public void unlock() { try { internalLock.unlock(); } catch (IllegalMonitorStateException ex) { log.warn("Unlock path:{} error for thread status change in concurrency", lockPath, ex); } } }（本文完 c-7-d e-a-20200324 真是有点滑稽，笔者发现任务持久化最好还是用现成的工业级调度器，于是基于Quartz做了轻量级封装，写了个后台管理界面，且听下回分解）