解析和缓存工作完成之后，接着分析最终激活所有调度任务的逻辑，见互斥方法afterSingletonsInstantiated()和onApplicationEvent()，两者中一定只有一个方法能够调用finishRegistration()：
// 所有单例实例化完毕之后回调 public void afterSingletonsInstantiated() { // Remove resolved singleton classes from cache this.nonAnnotatedClasses.clear(); if (this.applicationContext == null) { // Not running in an ApplicationContext -> register tasks early... finishRegistration(); } } // 上下文刷新完成之后回调 @Override public void onApplicationEvent(ContextRefreshedEvent event) { if (event.getApplicationContext() == this.applicationContext) { // Running in an ApplicationContext -> register tasks this late... // giving other ContextRefreshedEvent listeners a chance to perform // their work at the same time (e.g. Spring Batch's job registration). finishRegistration(); } } // private void finishRegistration() { // 如果持有的scheduler对象不为null则设置ScheduledTaskRegistrar中的任务调度器 if (this.scheduler != null) { this.registrar.setScheduler(this.scheduler); } // 这个判断一般会成立，得到的BeanFactory就是DefaultListableBeanFactory if (this.beanFactory instanceof ListableBeanFactory) { // 获取所有的调度配置器SchedulingConfigurer实例，并且都回调configureTasks()方法，这个很重要，它是用户动态装载调取任务的扩展钩子接口 Map<String, SchedulingConfigurer> beans = ((ListableBeanFactory) this.beanFactory).getBeansOfType(SchedulingConfigurer.class); List<SchedulingConfigurer> configurers = new ArrayList<>(beans.values()); // SchedulingConfigurer实例列表排序 AnnotationAwareOrderComparator.sort(configurers); for (SchedulingConfigurer configurer : configurers) { configurer.configureTasks(this.registrar); } } // 下面这一大段逻辑都是为了从BeanFactory取出任务调度器实例，主要判断TaskScheduler或者ScheduledExecutorService类型的Bean，包括尝试通过类型或者名字获取 // 获取成功后设置到ScheduledTaskRegistrar中 if (this.registrar.hasTasks() && this.registrar.getScheduler() == null) { Assert.state(this.beanFactory != null, "BeanFactory must be set to find scheduler by type"); try { // Search for TaskScheduler bean... this.registrar.setTaskScheduler(resolveSchedulerBean(this.beanFactory, TaskScheduler.class, false)); } catch (NoUniqueBeanDefinitionException ex) { logger.trace("Could not find unique TaskScheduler bean", ex); try { this.registrar.setTaskScheduler(resolveSchedulerBean(this.beanFactory, TaskScheduler.class, true)); } catch (NoSuchBeanDefinitionException ex2) { if (logger.isInfoEnabled()) { logger.info("More than one TaskScheduler bean exists within the context, and " + "none is named 'taskScheduler'. Mark one of them as primary or name it 'taskScheduler' " + "(possibly as an alias); or implement the SchedulingConfigurer interface and call " + "ScheduledTaskRegistrar#setScheduler explicitly within the configureTasks() callback: " + ex.getBeanNamesFound()); } } } catch (NoSuchBeanDefinitionException ex) { logger.trace("Could not find default TaskScheduler bean", ex); // Search for ScheduledExecutorService bean next... try { this.registrar.setScheduler(resolveSchedulerBean(this.beanFactory, ScheduledExecutorService.class, false)); } catch (NoUniqueBeanDefinitionException ex2) { logger.trace("Could not find unique ScheduledExecutorService bean", ex2); try { this.registrar.setScheduler(resolveSchedulerBean(this.beanFactory, ScheduledExecutorService.class, true)); } catch (NoSuchBeanDefinitionException ex3) { if (logger.isInfoEnabled()) { logger.info("More than one ScheduledExecutorService bean exists within the context, and " + "none is named 'taskScheduler'. Mark one of them as primary or name it 'taskScheduler' " + "(possibly as an alias); or implement the SchedulingConfigurer interface and call " + "ScheduledTaskRegistrar#setScheduler explicitly within the configureTasks() callback: " + ex2.getBeanNamesFound()); } } } catch (NoSuchBeanDefinitionException ex2) { logger.trace("Could not find default ScheduledExecutorService bean", ex2); // Giving up -> falling back to default scheduler within the registrar... logger.info("No TaskScheduler/ScheduledExecutorService bean found for scheduled processing"); } } } // 调用ScheduledTaskRegistrar的afterPropertiesSet()方法，装载所有的调度任务 this.registrar.afterPropertiesSet(); } public class ScheduledTaskRegistrar implements ScheduledTaskHolder, InitializingBean, DisposableBean { // 省略其他代码......... @Override public void afterPropertiesSet() { scheduleTasks(); } // 装载所有调度任务 @SuppressWarnings("deprecation") protected void scheduleTasks() { // 这里注意一点，如果找不到任务调度器实例，那么会用单个线程调度所有任务 if (this.taskScheduler == null) { this.localExecutor = Executors.newSingleThreadScheduledExecutor(); this.taskScheduler = new ConcurrentTaskScheduler(this.localExecutor); } // 调度所有装载完毕的自定义触发器的任务实例 if (this.triggerTasks != null) { for (TriggerTask task : this.triggerTasks) { addScheduledTask(scheduleTriggerTask(task)); } } // 调度所有装载完毕的CronTask if (this.cronTasks != null) { for (CronTask task : this.cronTasks) { addScheduledTask(scheduleCronTask(task)); } } // 调度所有装载完毕的FixedRateTask if (this.fixedRateTasks != null) { for (IntervalTask task : this.fixedRateTasks) { addScheduledTask(scheduleFixedRateTask(task)); } } // 调度所有装载完毕的FixedDelayTask if (this.fixedDelayTasks != null) { for (IntervalTask task : this.fixedDelayTasks) { addScheduledTask(scheduleFixedDelayTask(task)); } } } // 省略其他代码......... }注意两个个问题：