public Date next(Date date) {
        Calendar calendar = new GregorianCalendar();
        calendar.setTimeZone(this.timeZone);
        calendar.setTime(date);
        //1.設(shè)置下次執(zhí)行時(shí)間的毫秒為0，如上次任務(wù)執(zhí)行過程不足1秒，則calendar的時(shí)間會(huì)被設(shè)置成上次任務(wù)的執(zhí)行時(shí)間
        calendar.set(14, 0);
        long originalTimestamp = calendar.getTimeInMillis();
        this.doNext(calendar, calendar.get(1));
        //2.由于有上面一步，執(zhí)行時(shí)間太短，會(huì)導(dǎo)致下述條件為true
            if(calendar.getTimeInMillis() == originalTimestamp) {
        //3.calendar在原來的時(shí)間上增加1秒
            calendar.add(13, 1);
         //CronSequenceGenerator的doNext算法從指定時(shí)間開始(包括指定時(shí)間)查找符合cron表達(dá)式規(guī)則下一個(gè)匹配的時(shí)間
         //注意第一個(gè)匹配符是*，由于增加了1秒，依然符合cron="* 0/2 * * * *"，所以下一個(gè)執(zhí)行時(shí)間就是在原來的基礎(chǔ)上增加了一               秒
            this.doNext(calendar, calendar.get(1));
        }
        return calendar.getTime(); 

@Component
public class ScheduledTaskDemo {
    private static final Logger logger = LoggerFactory.getLogger(ScheduledTaskDemo.class); 
    @Scheduled(cron = "0/10 * * * * *")
    public void execute() {
        logger.info("Scheduled task is running... ...");
    }
}

@Component
public class SecondScheduledTaskDemo {
    private static final Logger logger = LoggerFactory.getLogger(ScheduledTaskDemo.class); 
    @Scheduled(cron = "0/10 * * * * *")
    public void second() {
        logger.info("Second scheduled task is starting... ...");
        logger.info("Second scheduled task is ending... ...");
    } 
}

*
 * <p>Processing of {@code @Scheduled} annotations is performed by
 * registering a {@link ScheduledAnnotationBeanPostProcessor}. This can be
 * done manually or, more conveniently, through the {@code <task:annotation-driven/>}
 * element or @{@link EnableScheduling} annotation.
 *

/**
     * Set the {@link org.springframework.scheduling.TaskScheduler} that will invoke
     * the scheduled methods, or a {@link java.util.concurrent.ScheduledExecutorService}
     * to be wrapped as a TaskScheduler.
     * <p>If not specified, default scheduler resolution will apply: searching for a
     * unique {@link TaskScheduler} bean in the context, or for a {@link TaskScheduler}
     * bean named "taskScheduler" otherwise; the same lookup will also be performed for
     * a {@link ScheduledExecutorService} bean. If neither of the two is resolvable,
     * a local single-threaded default scheduler will be created within the registrar.
     * @see #DEFAULT_TASK_SCHEDULER_BEAN_NAME
     */
    public void setScheduler(Object scheduler) {
        this.scheduler = scheduler;
    }

@Configuration
public class ScheduledTaskConfiguration implements SchedulingConfigurer { 
    /**
     * Callback allowing a {@link TaskScheduler
     * TaskScheduler} and specific {@link Task Task}
     * instances to be registered against the given the {@link ScheduledTaskRegistrar}
     *
     * @param taskRegistrar the registrar to be configured.
     */
    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        final ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();
        taskScheduler.setPoolSize(2);
        taskScheduler.initialize();
        taskRegistrar.setTaskScheduler(taskScheduler);
    }
}