解析spring schedule

Spring在schedule这块支持JDK Timer、concurrent、quartz三种，这三种任务调度方案在实现机制和调用方法上都不同，但spring通过对其包装，使得基于spring能用统一的配置和编码风格来使用这三种schedule方案。

总得来说这三种schedule都是基于scheduler->trigger->job的基本流程，因此spring通过TimerFactoryBean、ScheduledExecutorFactoryBean和SchedulerFactoryBean分别实现JDK Timer、concurrent和quartz的基本流程。主要逻辑如下代码所示：

TimerFactoryBean

public void afterPropertiesSet() {
		logger.info("Initializing Timer");
		this.timer = createTimer(this.beanName, this.daemon);
		// Register specified ScheduledTimerTasks, if necessary.
		if (!ObjectUtils.isEmpty(this.scheduledTimerTasks)) {
//注册task和timer			registerTasks(this.scheduledTimerTasks, this.timer);
		}
	}

ScheduledExecutorFactoryBean

public void afterPropertiesSet() {
		if (logger.isInfoEnabled()) {
			logger.info("Initializing ScheduledExecutorService" +
					(this.beanName != null ? " '" + this.beanName + "'" : ""));
		}
		ScheduledExecutorService executor =
				createExecutor(this.poolSize, this.threadFactory, this.rejectedExecutionHandler);
		// Register specified ScheduledExecutorTasks, if necessary.
		if (!ObjectUtils.isEmpty(this.scheduledExecutorTasks)) {
			registerTasks(this.scheduledExecutorTasks, executor);
		}
		// Wrap executor with an unconfigurable decorator.
		this.executor = (this.exposeUnconfigurableExecutor ?
				Executors.unconfigurableScheduledExecutorService(executor) : executor);
	}

SchedulerFactoryBean

public void afterPropertiesSet() throws Exception {
	.....
		// 初始化sceduler
		initSchedulerFactory(schedulerFactory);
		this.scheduler = createScheduler(schedulerFactory, this.schedulerName);
                //注册listener、trigger和job
		registerListeners();
		registerJobsAndTriggers();
       ......
                //启动scheduler
		startScheduler(this.scheduler, this.startupDelay);
       ......
		}
	}

顺着scheduler->trigger->job的思路，Spring又分别对JDK Timer、concurrent、quartz的trigger进行了封装，暴露出时间调度的配置参数，三种封装类分别为ScheduledTimerTask、ScheduledExecutorTask和CronTriggerBean+SimpleTriggerBean。三种trigger封装类分别根据实现机制的特点暴露出时间调度配置并串联起scheduler和具体job任务