springboot动态定时任务

spring boot通过注解@EnableScheduling和@Scheduled实现的是静态定时任务，不能动态添加、停止、修改等.
本文通过ThreadPoolTaskScheduler实现定时任务动态增删改.

• 静态定时任务参考

1. 创建ThreadPoolTaskScheduler

@Bean
public ThreadPoolTaskScheduler threadPoolTaskScheduler() {
    ThreadPoolTaskScheduler threadPoolTaskScheduler = new ThreadPoolTaskScheduler();
    threadPoolTaskScheduler.setPoolSize(10);
    threadPoolTaskScheduler.setRemoveOnCancelPolicy(true);
    return threadPoolTaskScheduler;
}

2. 创建一个全局任务记录表

@Data
public class Tasks {
    public static Map<String, ScheduledFuture<?>> tasks = new ConcurrentHashMap<>();
}

3. 创建一个任务类

public class MyRunnable implements Runnable {
    private String id;

    public MyRunnable(String id) {
        this.id = id;
    }

    @Override
    public void run() {
        System.out.println("id: " + this.id + " - " + new Date());
    }
}

4. 通过接口启动/删除/修改定时任务

   任务的元数据信息可以保存在数据库中.

@RestController
public class DynamicTask {
    @Autowired
    private ThreadPoolTaskScheduler threadPoolTaskScheduler;

    // 增加一个带id的定时任务
    @RequestMapping("/start")
    public String startCron(@RequestParam("id") String id) {
        if (Tasks.tasks.containsKey(id)) {
            return "exist";
        }
        ScheduledFuture<?> future = threadPoolTaskScheduler.schedule(new MyRunnable(id), new CronTrigger("0/5 * * * * *"));
        Tasks.tasks.put(id, future);
        return "start";
    }

    //根据id删除一个定时任务
    @RequestMapping("/stop")
    public String stopCron(@RequestParam("id") String id) {
        if (!Tasks.tasks.containsKey(id)) {
            return "not exist";
        }
        Tasks.tasks.get(id).cancel(true);
        Tasks.tasks.remove(id);
        return "stop";
    }

    //根据id修改定时任务
    @RequestMapping("/changeCron10")
    public String startCron10(@RequestParam("id") String id) {
        stopCron(id);// 先停止，在开启.
        ScheduledFuture<?> future = threadPoolTaskScheduler.schedule(new MyRunnable(id), new CronTrigger("*/10 * * * * *"));
        Tasks.tasks.put(id, future);
        return "change";
    }
}