Java getScheduler（）返回NULL

我正在尝试在分布式环境中使用quarts实现一个调度器。我正在使用它来实现它。但是scheduler.getScheduler（）返回NULL。有人请帮我理解这个问题

private static SchedulerFactoryBean scheduler = new SchedulerFactoryBean();
public void startSchedulers() {
    try {
        scheduler.start();
        // define the job 
        JobDetail job = JobBuilder.newJob(ArchiveJob.class)
                .withIdentity("archiveJob", "group1")  
                .build();

        // Trigger the job
        Trigger trigger = newTrigger()
                .withIdentity("archiveTriger", "group1")
                .startNow()
                .withSchedule(
                        SimpleScheduleBuilder.simpleSchedule()
                                .withIntervalInSeconds(60).repeatForever())
                .build();

        // Tell quartz to schedule the job using our trigger
        scheduler.getScheduler().scheduleJob(job, trigger);
    } catch (Exception ex) { 
    }
}