这里将定时任务的代码记录一下

参考视频地址：70行手搓一个定时任务

ScheduleService

package dhh.project.config.myschedule;


import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.locks.LockSupport;

/**
 * 手写定时任务
 *
 * @since 2025/6/3 05:55
 */
public class ScheduleService {

    Trigger trigger = new Trigger();

    ExecutorService executorService = Executors.newFixedThreadPool(6);

    public void schedule(Runnable task, long delay) {
        Job job = new Job();
        job.setTask(task);
        job.setStartTime(System.currentTimeMillis() + delay);
        job.setDelay(delay);
        trigger.queue.offer(job);
        trigger.wakeUp();
    }

    // 等待相应的时间，把任务添加到线程池中
    class Trigger {

        PriorityBlockingQueue<Job> queue = new PriorityBlockingQueue<>();

        Thread thread = new Thread(() -> {
            while (true) {
                // 不能使用if判断，存在虚假唤醒问题，使用while解决
                // Object
                while (queue.isEmpty()) {
                    LockSupport.park();
                }
                Job latelyJob = queue.peek();
                if (latelyJob.getStartTime() < System.currentTimeMillis()) {
                    latelyJob = queue.poll();
                    executorService.execute(latelyJob.getTask());
                    // 计算下一次执行的任务
                    Job nextJob = new Job();
                    nextJob.setTask(latelyJob.getTask());
                    nextJob.setDelay(latelyJob.getDelay());
                    nextJob.setStartTime(System.currentTimeMillis() + latelyJob.getDelay());
                    queue.offer(nextJob);
                } else {
                    LockSupport.parkUntil(latelyJob.getStartTime());
                }
            }
        });

        {
            thread.start();
            System.out.println("触发器启动了！");
        }

        // 唤醒，当有更小的startTime的任务传进来的时候
        void wakeUp() {
            LockSupport.unpark(thread);
        }
    }

}

Job

package dhh.project.config.myschedule;

import lombok.Data;

/**
 * 任务
 *
 * @since 2025/6/3 06:08
 */
@Data
public class Job implements Comparable<Job> {

    private Runnable task;

    private long startTime;

    private long delay;

    @Override
    public int compareTo(Job o) {
        return Long.compare(this.startTime, o.startTime);
    }
}

ScheduleServiceTest

package dhh.project;

import dhh.project.config.myschedule.ScheduleService;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

/**
 * 手写定时任务测试类
 *
 * @since 2025/6/3 05:57
 */
public class ScheduleServiceTest {

    public static void main(String[] args) throws InterruptedException {
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("HH:mm:ss SSS");
        ScheduleService scheduleService = new ScheduleService();
        scheduleService.schedule(() -> {
            System.out.println(LocalDateTime.now().format(formatter) + "这里100ms的");
        }, 100);

        Thread.sleep(1000);
        System.out.println("添加一个每200ms执行的定时任务！");

        scheduleService.schedule(() -> {
            System.out.println(LocalDateTime.now().format(formatter) + "这里200ms的");
        }, 200);
    }
}

Changelog

10/10/25, 3:04 PM

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• 1ee1e-feat(wiki): algo -on 10/10/25