对spring任务定时器的动态修改

        很多时候，spring的quartz定时任务并不能完全满足项目的需要，经常会遇到需要任务的执行时间和频率是可控的，而不是写死在 quartz配置xml上面。为此，思考了很多动态修改任务执行的方法，以下方法是通过获取scheduler，对trigger的时间表达式进行修改，并重启任务去实现任务的动态变化。

public class QuartzHandler {public static final String DEFAULT_GROUP_NAME = "DEFAULT";private static QuartzHandler instance = new QuartzHandler();private static Logger logger = Logger.getLogger(QuartzHandler.class);private QuartzManager quartzManager;private Scheduler scheduler;private ApplicationContext context;private QuartzHandler() {}public static QuartzHandler genInstance() {return instance;}/** * 开始定时任务 */public void start() {context = new ClassPathXmlApplicationContext("spring/applicationContext.xml");scheduler = (StdScheduler) context.getBean("schedulerFactory");quartzManager = (QuartzManager) context.getBean("quartzManager");}/** * 更新定时任务的触发表达式 *  * @param triggerName *            触发器名字 * @param groupName *            触发器组名字 * @param cronExpression *            触发表达式 * @return 成功则返回true，否则返回false */public boolean updateCronExpression(String triggerName, String groupName,String cronExpression) {try {CronTrigger trigger = (CronTrigger) getTrigger(triggerName,groupName);if (trigger == null) {return false;}if (StringUtils.equals(trigger.getCronExpression(), cronExpression)) {logger.info("cronExpression is same with the running Schedule , no need to update.");return true;}trigger.setCronExpression(cronExpression);scheduler.rescheduleJob(trigger.getName(), trigger.getGroup(),trigger);logger.info("Update the cronExpression successfully!!");return true;} catch (ParseException e) {logger.error("The new cronExpression - " + cronExpression+ " not conform to the standard. " + e);return false;} catch (SchedulerException e) {logger.error("Fail to reschedule. " + e);return false;}}/** * 获取触发器 *  * @param triggerName *            触发器名字 * @param groupName *            触发器组名字 * @return 对应Trigger */public Trigger getTrigger(String triggerName, String groupName) {Trigger trigger = null;if (StringUtils.isBlank(groupName)) {logger.warn("Schedule Job Group is empty!");return null;}if (StringUtils.isBlank(triggerName)) {logger.warn("Schedule trigger Name is empty!");return null;}try {trigger = scheduler.getTrigger(triggerName, groupName);} catch (SchedulerException e) {logger.warn("Fail to get the trigger (triggerName: " + triggerName+ ", groupName : " + groupName + ")");return null;}if (trigger == null) {logger.warn("Can not found the trigger of triggerName: "+ triggerName + ", groupName : " + groupName);}return trigger;}}