xxl-job如何停止某一个任务？

停止，通过quartz调度器的unscheduleJob()方法，取消quartz的调度。

public ReturnT<String> stop(int id) {
        XxlJobInfo xxlJobInfo = xxlJobInfoDao.loadById(id);
        String group = String.valueOf(xxlJobInfo.getJobGroup());
        String name = String.valueOf(xxlJobInfo.getId());

  try {
    // bind quartz
            boolean ret = XxlJobDynamicScheduler.removeJob(name, group);
            return ret?ReturnT.SUCCESS:ReturnT.FAIL;
  } catch (SchedulerException e) {
    logger.error(e.getMessage(), e);
    return ReturnT.FAIL;
  }
  }

public static boolean removeJob(String jobName, String jobGroup) throws SchedulerException {

        TriggerKey triggerKey = TriggerKey.triggerKey(jobName, jobGroup);

if (scheduler.checkExists(triggerKey)) {
            scheduler.unscheduleJob(triggerKey);    // trigger + job
        }

        logger.info(">>>>>>>>>>> removeJob success, triggerKey:{}", triggerKey);
        return true;
    }