【企業級定時任務Quartz】---如何防止定時任務併發

前言

最近項目中在使用企業級定時任務Quartz，在使用過程中，發現一個問題就是我們如何防止定時任務的併發？

---

定時任務的併發

• 正常執行
  
• 併發
  
  通過上面的圖片，我們瞭解了併發任務，在實際的項目開發中，如何防止併發呢？
  @DisallowConcurrentExecution 防止併發

模擬併發

package com.zcw;

import com.zcw.job.MyJob;
import org.quartz.*;
import org.quartz.impl.StdSchedulerFactory;

/**
 * @ClassName : QuartzDemo
 * @Description :啓動類
 * @Author : Zhaocunwei
 * @Date: 2020-06-09 13:31
 */
public class QuartzDemo {
    public static void main(String[] args) throws SchedulerException {
        Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();
        scheduler.start();
        //配置任務
        JobDetail jobDetail = JobBuilder.newJob(MyJob.class)
                .withIdentity("jobDetail1","group1")
                .usingJobData("name","zcw")
                .build();
        //創建觸發器
        Trigger trigger = TriggerBuilder.newTrigger()
                .startNow()
                .withSchedule(SimpleScheduleBuilder.simpleSchedule()
                //時間間隔爲5秒
                .withIntervalInSeconds(5)
                .repeatForever()
                ).build();

        scheduler.scheduleJob(jobDetail,trigger);

        try {
            Thread.sleep(600000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        scheduler.shutdown();
    }
}

• job類

package com.zcw.job;

import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.quartz.*;

import java.time.LocalTime;

/**
 * @ClassName : MyJob
 * @Description :
 * @Author : Zhaocunwei
 * @Date: 2020-06-09 13:32
 */
@Data
public class MyJob implements Job {

    private String name;


    @Override
    public void execute(JobExecutionContext context) throws JobExecutionException {
        LocalTime localTime = LocalTime.now();
        System.out.println(Thread.currentThread().getName()+"開始執行！"+localTime.toString());
        try {
            Thread.sleep(7000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        LocalTime endTime = LocalTime.now();
        System.out.println("結束時間！"+endTime.toString());

    }
}

• 測試結果
  

優化代碼，解決併發添加註解

package com.zcw.job;

import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.quartz.*;

import java.time.LocalTime;
import java.util.concurrent.ThreadPoolExecutor;

/**
 * @ClassName : MyJob
 * @Description :
 * @Author : Zhaocunwei
 * @Date: 2020-06-09 13:32
 */
@Data
@DisallowConcurrentExecution
public class MyJob implements Job {

    private String name;


    @Override
    public void execute(JobExecutionContext context) throws JobExecutionException {
        LocalTime localTime = LocalTime.now();
        System.out.println(Thread.currentThread().getName()+"開始執行！"+localTime.toString());
        try {
            Thread.sleep(7000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        LocalTime endTime = LocalTime.now();
        System.out.println(Thread.currentThread().getName()+"結束時間！"+endTime.toString());

    }
}

• 測試
  

JobDataMap的更新

在這裏主要是演示一個@PersistJobDataAfterExecution可更新JobDataMap註解，把數據持久化到我們的jobDataMap中。

• 測試
  
  通過上面的演示，我們的count值沒有增加，需要每次執行一次count＋1；
  

package com.zcw.job;

import lombok.Data;
import org.quartz.*;

import java.time.LocalTime;

/**
 * @ClassName : MyJob
 * @Description :
 * @Author : Zhaocunwei
 * @Date: 2020-06-09 13:32
 */
@Data
@PersistJobDataAfterExecution
public class MyJob implements Job {

    private int count;


    @Override
    public void execute(JobExecutionContext context) throws JobExecutionException {
        LocalTime localTime = LocalTime.now();
        count++;
        context.getJobDetail().getJobDataMap().put("count",count);
        System.out.println(localTime.toString()+",count值="+count);


    }
}

• 測試