10. xxl-job原理---回调

xxl-job: v2.0.2 原理 目录学习

执行器

在执行器开始的时候，会开启一个回调线程，TriggerCallbackThread.getInstance().start();
该线程不断查找从 回调队列callBackQueue中查找回调信息，用就进行回调doCallback(callbackParamList);

admin

执行器通过回调线程，会调用admin中AdminBizImpl.callback() 方法， 然后执行。

回调源代码

AdminBizImpl.callback

private ReturnT<String> callback(HandleCallbackParam handleCallbackParam) {
        // valid log item
        XxlJobLog log = xxlJobLogDao.load(handleCallbackParam.getLogId());
        if (log == null) {
            return new ReturnT<String>(ReturnT.FAIL_CODE, "log item not found.");
        }
        if (log.getHandleCode() > 0) {
            return new ReturnT<String>(ReturnT.FAIL_CODE, "log repeate callback.");     // avoid repeat callback, trigger child job etc
        }

        // trigger success, to trigger child job
        String callbackMsg = null;
        if (IJobHandler.SUCCESS.getCode() == handleCallbackParam.getExecuteResult().getCode()) {
            XxlJobInfo xxlJobInfo = xxlJobInfoDao.loadById(log.getJobId());
            if (xxlJobInfo!=null && xxlJobInfo.getChildJobId()!=null && xxlJobInfo.getChildJobId().trim().length()>0) {
                callbackMsg = "<br><br><span style=\"color:#00c0ef;\" > >>>>>>>>>>>"+ I18nUtil.getString("jobconf_trigger_child_run") +"<<<<<<<<<<< </span><br>";

                String[] childJobIds = xxlJobInfo.getChildJobId().split(",");
                for (int i = 0; i < childJobIds.length; i++) {
                    int childJobId = (childJobIds[i]!=null && childJobIds[i].trim().length()>0 && isNumeric(childJobIds[i]))?Integer.valueOf(childJobIds[i]):-1;
                    if (childJobId > 0) {

                        JobTriggerPoolHelper.trigger(childJobId, TriggerTypeEnum.PARENT, -1, null, null);
                        ReturnT<String> triggerChildResult = ReturnT.SUCCESS;

                        // add msg
                        callbackMsg += MessageFormat.format(I18nUtil.getString("jobconf_callback_child_msg1"),
                                (i+1),
                                childJobIds.length,
                                childJobIds[i],
                                (triggerChildResult.getCode()==ReturnT.SUCCESS_CODE?I18nUtil.getString("system_success"):I18nUtil.getString("system_fail")),
                                triggerChildResult.getMsg());
                    } else {
                        callbackMsg += MessageFormat.format(I18nUtil.getString("jobconf_callback_child_msg2"),
                                (i+1),
                                childJobIds.length,
                                childJobIds[i]);
                    }
                }

            }
        }

        // handle msg
        StringBuffer handleMsg = new StringBuffer();
        if (log.getHandleMsg()!=null) {
            handleMsg.append(log.getHandleMsg()).append("<br>");
        }
        if (handleCallbackParam.getExecuteResult().getMsg() != null) {
            handleMsg.append(handleCallbackParam.getExecuteResult().getMsg());
        }
        if (callbackMsg != null) {
            handleMsg.append(callbackMsg);
        }

        // success, save log
        log.setHandleTime(new Date());
        log.setHandleCode(handleCallbackParam.getExecuteResult().getCode());
        log.setHandleMsg(handleMsg.toString());
        xxlJobLogDao.updateHandleInfo(log);

        return ReturnT.SUCCESS;
    }

tips: 好像，只有有子任务的任务才可以进行回调， 如果想执行一个特定的命令时无法 进行回调

PS: 若你觉得可以、还行、过得去、甚至不太差的话，可以“关注”一下，就此谢过!