spring定时任务原理

@EnableAsync
@EnableScheduling
@SpringBootApplication
public classQuickMediaApplication {

    public static voidmain(String[] args) {
        SpringApplication.run(QuickMediaApplication.class, args);
    }

    @Scheduled(cron = "0/1 * * * * ?")
    @Async
    public voidsc1()  {
        System.out.println(Thread.currentThread().getName() + " | sc1 " +System.currentTimeMillis());
    }
}

@Bean
publicAsyncTaskExecutor asyncTaskExecutor() {
    ThreadPoolTaskExecutor executor = newThreadPoolTaskExecutor();
    executor.setThreadNamePrefix("task-schedule-");
    executor.setMaxPoolSize(10);
    executor.setCorePoolSize(3);
    executor.setQueueCapacity(0);
    executor.setRejectedExecutionHandler(newThreadPoolExecutor.AbortPolicy());
    returnexecutor;
}

或

@Bean
publicScheduleExecutorService scheduleExecutorService{
    return Executors.new ScheduleThreadPool(10);    
}

spring.task.scheduling.pool.size=10spring.task.scheduling.thread-name-prefix=task-schedule-

public classScheduledAnnotationBeanPostProcessor
        implementsScheduledTaskHolder, MergedBeanDefinitionPostProcessor, DestructionAwareBeanPostProcessor,
        Ordered, EmbeddedValueResolverAware, BeanNameAware, BeanFactoryAware, ApplicationContextAware,
        SmartInitializingSingleton, ApplicationListener<ContextRefreshedEvent>, DisposableBean {
................

    @Override
    public voidonApplicationEvent(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 voidfinishRegistration() {
        if (this.scheduler != null) {
            this.registrar.setScheduler(this.scheduler);
        }

        .......................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(beanFactory, TaskScheduler.class, false));
            }
            catch(NoUniqueBeanDefinitionException ex) {
                logger.debug("Could not find unique TaskScheduler bean", ex);
                try{
                    this.registrar.setTaskScheduler(resolveSchedulerBean(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.debug("Could not find default TaskScheduler bean", ex);
                //Search for ScheduledExecutorService bean next...
                try{
                    this.registrar.setScheduler(resolveSchedulerBean(beanFactory, ScheduledExecutorService.class, false));
                }
                catch(NoUniqueBeanDefinitionException ex2) {
                    logger.debug("Could not find unique ScheduledExecutorService bean", ex2);
                    try{
                        this.registrar.setScheduler(resolveSchedulerBean(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.debug("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");
                }
            }
        }

        this.registrar.afterPropertiesSet();
    }
}

if (this.taskScheduler == null) {
      this.localExecutor =Executors.newSingleThreadScheduledExecutor();
      this.taskScheduler = new ConcurrentTaskScheduler(this.localExecutor);
}