1.ScheduledAnnotationBeanPostProcessor

@EnableScheduling

• @Import(SchedulingConfiguration.class)
• 注冊了ScheduledAnnotationBeanPostProcessor

@RestController
@RefreshScope  //動態(tài)感知修改后的值
public class TestController implements ApplicationListener<RefreshScopeRefreshedEvent>{
    @Value("${common.age}")
     String age;
    @Value("${common.name}")
     String name;
    @GetMapping("/common")
    public String hello() {
        return name+","+age;
    }
    //觸發(fā)@RefreshScope執(zhí)行邏輯會導(dǎo)致@Scheduled定時任務(wù)失效
    @Scheduled(cron = "*/3 * * * * ?")  //定時任務(wù)每隔3s執(zhí)行一次
    public void execute() {
        System.out.println("定時任務(wù)正常執(zhí)行。。。。。。");
    }
    @Override
    public void onApplicationEvent(RefreshScopeRefreshedEvent event) {
        this.execute();
    }
}

1.1 SmartInitializingSingleton#afterSingletonsInstantiated

ScheduledAnnotationBeanPostProcessor#afterSingletonsInstantiated

• DefaultListableBeanFactory#preInstantiateSingletons
• SmartInitializingSingleton#afterSingletonsInstantiated
• 沒干啥重要事情

1.2 RefreshScope處理ContextRefreshedEvent創(chuàng)建refresh中的bean

并調(diào)用ScheduledAnnotationBeanPostProcessor#postProcessAfterInitialization找出TestController中加了@Scheduled注解的方法。

ScheduledAnnotationBeanPostProcessor#postProcessAfterInitialization

• 發(fā)布ContextRefreshedEvent
• RefreshScope#onApplicationEvent
• Object bean = this.context.getBean(name); 獲取scope為refresh的bean：scopedTarget.testController
• 會調(diào)用至postProcessAfterInitialization
• 找到有@Scheduled注解的方法execute()
• tasks.add(this.registrar.scheduleCronTask(new CronTask(runnable, new CronTrigger(cron, timeZone))));

1.3 ScheduledAnnotationBeanPostProcessor本身也能處理ContextRefreshedEvent

這里真正開始調(diào)度1.2中找到的任務(wù)。

ScheduledAnnotationBeanPostProcessor#onApplicationEvent

• ScheduledAnnotationBeanPostProcessor也會處理ContextRefreshedEvent
• ScheduledAnnotationBeanPostProcessor#finishRegistration
• this.taskScheduler設(shè)置為ThreadPoolTaskScheduler（哪里配置的？）
• ScheduledTaskRegistrar#afterPropertiesSet
• ScheduledTaskRegistrar#scheduleTasks
• 開始執(zhí)行任務(wù)，這cronTasks不為空，則執(zhí)行該任務(wù)
  addScheduledTask(scheduleCronTask(task));
• ScheduledTaskRegistrar#scheduleCronTask
• scheduledTask.future = this.taskScheduler.schedule(task.getRunnable(), task.getTrigger());
• ThreadPoolTaskScheduler#schedule
• ReschedulingRunnable#schedule以及ReschedulingRunnable#run實現(xiàn)定時調(diào)度，線程池為ScheduledThreadPoolExecutor

2.@RefreshScope的影響

當Nacos Config配置中心發(fā)布配置時，會調(diào)用RefreshScope#refreshAll。
此時會ScheduledAnnotationBeanPostProcessor#postProcessBeforeDestruction會將加了@RefreshScope的TestController里面的任務(wù)全部cancel掉。

    public void refreshAll() {
        super.destroy();
        this.context.publishEvent(new RefreshScopeRefreshedEvent());
    }

RefreshScope#refreshAll

• GenericScope.BeanLifecycleWrapper#destroy
• DisposableBeanAdapter#run
• ScheduledAnnotationBeanPostProcessor#postProcessBeforeDestruction會將TestController里面的任務(wù)全部cancel掉。

ScheduledAnnotationBeanPostProcessor#postProcessBeforeDestruction

    @Override
    public void postProcessBeforeDestruction(Object bean, String beanName) {
        Set<ScheduledTask> tasks;
        synchronized (this.scheduledTasks) {
            tasks = this.scheduledTasks.remove(bean);
        }
        if (tasks != null) {
            for (ScheduledTask task : tasks) {
                task.cancel();
            }
        }
    }

取消核心流程GenericScope#destroy()

    public void destroy() {
        List<Throwable> errors = new ArrayList<Throwable>();
        Collection<BeanLifecycleWrapper> wrappers = this.cache.clear();
        for (BeanLifecycleWrapper wrapper : wrappers) {
            try {
                Lock lock = this.locks.get(wrapper.getName()).writeLock();
                lock.lock();
                try {
                    wrapper.destroy();
                }
                finally {
                    lock.unlock();
                }
            }
            catch (RuntimeException e) {
                errors.add(e);
            }
        }
        if (!errors.isEmpty()) {
            throw wrapIfNecessary(errors.get(0));
        }
        this.errors.clear();
    }

2.1 ThreadPoolTaskScheduler在哪里配置的？

ThreadPoolTaskScheduler

• 構(gòu)造bean：nacosWatch：NacosWatch時會創(chuàng)建一個
• 構(gòu)造bean：taskScheduler：ThreadPoolTaskScheduler

public class TaskSchedulingAutoConfiguration {
    @Bean
    @ConditionalOnBean(name = TaskManagementConfigUtils.SCHEDULED_ANNOTATION_PROCESSOR_BEAN_NAME)
    @ConditionalOnMissingBean({ SchedulingConfigurer.class, TaskScheduler.class, ScheduledExecutorService.class })
    public ThreadPoolTaskScheduler taskScheduler(TaskSchedulerBuilder builder) {
        return builder.build();
    }
    @Bean
    @ConditionalOnMissingBean
    public TaskSchedulerBuilder taskSchedulerBuilder(TaskSchedulingProperties properties,
            ObjectProvider<TaskSchedulerCustomizer> taskSchedulerCustomizers) {
        TaskSchedulerBuilder builder = new TaskSchedulerBuilder();
        builder = builder.poolSize(properties.getPool().getSize());
        Shutdown shutdown = properties.getShutdown();
        builder = builder.awaitTermination(shutdown.isAwaitTermination());
        builder = builder.awaitTerminationPeriod(shutdown.getAwaitTerminationPeriod());
        builder = builder.threadNamePrefix(properties.getThreadNamePrefix());
        builder = builder.customizers(taskSchedulerCustomizers);
        return builder;
    }

2.2 TestController改造成ApplicationListener<RefreshScopeRefreshedEvent>

這樣做為什么能夠保證定時任務(wù)正常執(zhí)行？

• RefreshScope#refreshAll
• 發(fā)布RefreshScopeRefreshedEvent事件
• 調(diào)用到TestController代理對象#onApplicationEvent
• CglibAopProxy.DynamicAdvisedInterceptor#intercept
• SimpleBeanTargetSource#getTarget
• AbstractBeanFactory#getBean獲取scopedTarget.testController
• GenericScope#get
• 會創(chuàng)建真正的TestController實例，然后初始化后調(diào)用ScheduledAnnotationBeanPostProcessor#postProcessAfterInitialization找出TestController中加了@Scheduled注解的方法
• TestController#onApplicationEvent
• this.execute();
• 真正調(diào)用的是ReschedulingRunnable#run

以上就是@Scheduled定時器原理及@RefreshScope相互影響的詳細內(nèi)容，更多關(guān)于Scheduled定時器RefreshScope的資料請關(guān)注腳本之家其它相關(guān)文章！

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