我正在运行这个quartz-2.1.0\examples\src\main\java\org\quartz\examples\example3示例代码，它运行得非常好，但是如果我把CronTriggerExample.java中的main代码移到一个junit测试类中，这个作业就不会运行了。下面是quartz示例代码（为了简化起见，我将其截断，您可以从quartz网站获得完整的代码）。

简单作业.java：

public class SimpleJob implements Job {
  private static Logger _log = LoggerFactory.getLogger(SimpleJob.class);

  public void execute(JobExecutionContext context) throws JobExecutionException {
    JobKey jobKey = context.getJobDetail().getKey();
    _log.info("SimpleJob says: " + jobKey + " executing at " + new Date());
  }
}

CronTrigger示例.java：

public class CronTriggerExample {
    public void run() throws Exception {
        Logger log = LoggerFactory.getLogger(CronTriggerExample.class);
        SchedulerFactory sf = new StdSchedulerFactory();
        Scheduler sched = sf.getScheduler();
        JobDetail job = newJob(SimpleJob.class)
            .withIdentity("job1", "group1")
            .build();
        CronTrigger trigger = newTrigger()
            .withIdentity("trigger1", "group1")
            .withSchedule(cronSchedule("0/3 * * * * ?"))
            .build();

        Date ft = sched.scheduleJob(job, trigger);
        log.info(job.getKey() + " has been scheduled to run at: " + ft
            + " and repeat based on expression: "
            + trigger.getCronExpression());

        sched.start();
    }

    public static void main(String[] args) throws Exception {
        CronTriggerExample example = new CronTriggerExample();
        example.run();
    }
}

如果我把main方法中的两行代码移到一个junit测试类（junit4）中，上面的代码运行良好，如下所示：

public class Test1 {
    @Test
    public void run() throws Exception {
        CronTriggerExample example = new CronTriggerExample();
        example.run();
    }
}

则作业不运行。
我很困惑为什么同样的代码不能在junit中运行？