石英：在Jobs.xml中阻止作业的并发实例

当您的Quartz作业唤醒时，您可以执行以下操作：

JobDetail existingJobDetail = sched.getJobDetail(jobName, jobGroup);    if (existingJobDetail != null) {        List<JobExecutionContext> currentlyExecutingJobs = (List<JobExecutionContext>) sched.getCurrentlyExecutingJobs();        for (JobExecutionContext jec : currentlyExecutingJobs) { if(existingJobDetail.equals(jec.getJobDetail())) {     //String message = jobName + " is already running.";     //log.info(message);     //throw new JobExecutionException(message,false); }        }        //sched.deleteJob(jobName, jobGroup); if you want to delete the scheduled but not-currently-running job    }