【Spring boot】【cron】Spring boot 实现动态变更定时任务的cron表达式，动态生效

1.你的启动类上要有它

@SpringBootApplication
@EnableScheduling
public class JobApplication  {
    public static void main(String[] args) {
        try {
            SpringApplication.run(JobApplication.class);
            System.out.println("JobApplication 启动成功。。。");
        } catch (Exception e) {
            DpeLogUtil.error("JobApplication 启动失败", e);
        }
    }
}

2.你得有一个执行定时任务，且监听动态cron的 Job

import org.apache.commons.lang.StringUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.scheduling.Trigger;
import org.springframework.scheduling.TriggerContext;
import org.springframework.scheduling.annotation.SchedulingConfigurer;
import org.springframework.scheduling.config.ScheduledTaskRegistrar;
import org.springframework.scheduling.support.CronTrigger;
import org.springframework.stereotype.Component;

import java.util.Date;

@Component
public class MyAlterTaskPushJob implements SchedulingConfigurer {

    //默认5秒执行一次
    @Value("0/5 * * * * ?")
    private String cron;

    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {

        DpeLogUtil.resetLogFlag(null, LoggerNameEnum.JOB_LOGGER);

        taskRegistrar.addTriggerTask(
                new Runnable() {
                                         @Override
                                         public void run() {
                                            try {
                                                DpeLogUtil.info("MyAlterTaskPushJob#Runnable#  cron={}", cron);
                                                DpeLogUtil.info("MyAlterTaskPushJob#Runnable#  做你的业务 boy");
                                            }catch (Exception e) {

                                            }
                                         }
                                     },
                new Trigger() {
                    @Override
                    public Date nextExecutionTime(TriggerContext triggerContext) {
                        DpeLogUtil.info("MyAlterTaskPushJob#Trigger#  cron={}", cron);
                        if (StringUtils.isBlank(cron)) {
                            return null;
                        }
                        //定时任务触发，可修改定时任务的执行周期
                        CronTrigger cronTrigger = new CronTrigger(cron);
                        Date nextExecDate = cronTrigger.nextExecutionTime(triggerContext);
                        return nextExecDate;
                    }
                }
        );
    }


    public String getCron() {
        return cron;
    }

    public void setCron(String cron) {
        this.cron = cron;
    }
}

3.我们试一试去动态变更它

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.annotation.Resource;

@Controller
@RequestMapping("/alert")
public class MyController {
    @Resource
    MyAlterTaskPushJob alterTaskPushJob;

    @RequestMapping(value = "/update", method = {RequestMethod.GET, RequestMethod.POST})
    @ResponseBody
    public  String  update(Integer num){
        String cron = "0/"+num+" * * * * ?";
        alterTaskPushJob.setCron(cron);
        return "干你母";
    }

}

4.直接看效果

一开始，都是按照默认cron设置 5s执行一次

接着我们动态变更一下

接收到变更后，发现 cron动态变了，接下来看执行时间是否间隔发生变化

执行时段  已变成2s执行一次