Spring Boot 定时任务，怎么实现任务动态增删启停？

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作者：jessehua
链接：https://www.jianshu.com/p/0f68936393fd

在spring boot项目中，可以通过@EnableScheduling注解和@Scheduled注解实现定时任务，也可以通过SchedulingConfigurer接口来实现定时任务。但是这两种方式不能动态添加、删除、启动、停止任务。要实现动态增删启停定时任务功能，比较广泛的做法是集成Quartz框架。

但是本人的开发原则是：在满足项目需求的情况下，尽量少的依赖其它框架，避免项目过于臃肿和复杂。查看spring-context这个jar包中org.springframework.scheduling.ScheduledTaskRegistrar这个类的源代码，发现可以通过改造这个类就能实现动态增删启停定时任务功能。

Spring Boot 基础就不介绍了，推荐下这个实战教程： https://github.com/javastacks/spring-boot-best-practice

添加执行定时任务的线程池配置类

@Configuration
public class SchedulingConfig {
    @Bean
    public TaskScheduler taskScheduler() {
        ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();
        // 定时任务执行线程池核心线程数
        taskScheduler.setPoolSize(4);
        taskScheduler.setRemoveOnCancelPolicy(true);
        taskScheduler.setThreadNamePrefix("TaskSchedulerThreadPool-");
        return taskScheduler;
    }
}

添加ScheduledFuture的包装类。ScheduledFuture是ScheduledExecutorService定时任务线程池的执行结果。

public final class ScheduledTask {

    volatile ScheduledFuture<?> future;

    /**
     * 取消定时任务
     */
    public void cancel() {
        ScheduledFuture<?> future = this.future;
        if (future != null) {
            future.cancel(true);
        }
    }
}

添加Runnable接口实现类，被定时任务线程池调用，用来执行指定bean里面的方法。

public class SchedulingRunnable implements Runnable {

    private static final Logger logger = LoggerFactory.getLogger(SchedulingRunnable.class);

    private String beanName;

    private String methodName;

    private String params;

    public SchedulingRunnable(String beanName, String methodName) {
        this(beanName, methodName, null);
    }

    public SchedulingRunnable(String beanName, String methodName, String params) {
        this.beanName = beanName;
        this.methodName = methodName;
        this.params = params;
    }

    @Override
    public void run() {
        logger.info("定时任务开始执行 - bean：{}，方法：{}，参数：{}", beanName, methodName, params);
        long startTime = System.currentTimeMillis();

        try {
            Object target = SpringContextUtils.getBean(beanName);

            Method method = null;
            if (StringUtils.isNotEmpty(params)) {
                method = target.getClass().getDeclaredMethod(methodName, String.class);
            } else {
                method = target.getClass().getDeclaredMethod(methodName);
            }

            ReflectionUtils.makeAccessible(method);
            if (StringUtils.isNotEmpty(params)) {
                method.invoke(target, params);
            } else {
                method.invoke(target);
            }
        } catch (Exception ex) {
            logger.error(String.format("定时任务执行异常 - bean：%s，方法：%s，参数：%s ", beanName, methodName, params), ex);
        }

        long times = System.currentTimeMillis() - startTime;
        logger.info("定时任务执行结束 - bean：{}，方法：{}，参数：{}，耗时：{} 毫秒", beanName, methodName, params, times);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        SchedulingRunnable that = (SchedulingRunnable) o;
        if (params == null) {
            return beanName.equals(that.beanName) &&
                    methodName.equals(that.methodName) &&
                    that.params == null;
        }

        return beanName.equals(that.beanName) &&
                methodName.equals(that.methodName) &&
                params.equals(that.params);
    }

    @Override
    public int hashCode() {
        if (params == null) {
            return Objects.hash(beanName, methodName);
        }

        return Objects.hash(beanName, methodName, params);
    }
}

添加定时任务注册类，用来增加、删除定时任务。

@Component
public class CronTaskRegistrar implements DisposableBean {

    private final Map<Runnable, ScheduledTask> scheduledTasks = new ConcurrentHashMap<>(16);

    @Autowired
    private TaskScheduler taskScheduler;

    public TaskScheduler getScheduler() {
        return this.taskScheduler;
    }

    public void addCronTask(Runnable task, String cronExpression) {
        addCronTask(new CronTask(task, cronExpression));
    }

    public void addCronTask(CronTask cronTask) {
        if (cronTask != null) {
            Runnable task = cronTask.getRunnable();
            if (this.scheduledTasks.containsKey(task)) {
                removeCronTask(task);
            }

            this.scheduledTasks.put(task, scheduleCronTask(cronTask));
        }
    }

    public void removeCronTask(Runnable task) {
        ScheduledTask scheduledTask = this.scheduledTasks.remove(task);
        if (scheduledTask != null)
            scheduledTask.cancel();
    }

    public ScheduledTask scheduleCronTask(CronTask cronTask) {
        ScheduledTask scheduledTask = new ScheduledTask();
        scheduledTask.future = this.taskScheduler.schedule(cronTask.getRunnable(), cronTask.getTrigger());

        return scheduledTask;
    }


    @Override
    public void destroy() {
        for (ScheduledTask task : this.scheduledTasks.values()) {
            task.cancel();
        }

        this.scheduledTasks.clear();
    }
}

添加定时任务示例类

@Component("demoTask")
public class DemoTask {
    public void taskWithParams(String params) {
        System.out.println("执行有参示例任务：" + params);
    }

    public void taskNoParams() {
        System.out.println("执行无参示例任务");
    }
}

定时任务数据库表设计

添加定时任务实体类

public class SysJobPO {
    /**
     * 任务ID
     */
    private Integer jobId;
    /**
     * bean名称
     */
    private String beanName;
    /**
     * 方法名称
     */
    private String methodName;
    /**
     * 方法参数
     */
    private String methodParams;
    /**
     * cron表达式
     */
    private String cronExpression;
    /**
     * 状态（1正常 0暂停）
     */
    private Integer jobStatus;
    /**
     * 备注
     */
    private String remark;
    /**
     * 创建时间
     */
    private Date createTime;
    /**
     * 更新时间
     */
    private Date updateTime;

    public Integer getJobId() {
        return jobId;
    }

    public void setJobId(Integer jobId) {
        this.jobId = jobId;
    }

    public String getBeanName() {
        return beanName;
    }

    public void setBeanName(String beanName) {
        this.beanName = beanName;
    }

    public String getMethodName() {
        return methodName;
    }

    public void setMethodName(String methodName) {
        this.methodName = methodName;
    }

    public String getMethodParams() {
        return methodParams;
    }

    public void setMethodParams(String methodParams) {
        this.methodParams = methodParams;
    }

    public String getCronExpression() {
        return cronExpression;
    }

    public void setCronExpression(String cronExpression) {
        this.cronExpression = cronExpression;
    }

    public Integer getJobStatus() {
        return jobStatus;
    }

    public void setJobStatus(Integer jobStatus) {
        this.jobStatus = jobStatus;
    }

    public String getRemark() {
        return remark;
    }

    public void setRemark(String remark) {
        this.remark = remark;
    }

    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    public Date getUpdateTime() {
        return updateTime;
    }

    public void setUpdateTime(Date updateTime) {
        this.updateTime = updateTime;
    }

}

新增定时任务

新增定时任务

boolean success = sysJobRepository.addSysJob(sysJob);
if (!success)
    return OperationResUtils.fail("新增失败");
else {
    if (sysJob.getJobStatus().equals(SysJobStatus.NORMAL.ordinal())) {
        SchedulingRunnable task = new SchedulingRunnable(sysJob.getBeanName(), sysJob.getMethodName(), sysJob.getMethodParams());
        cronTaskRegistrar.addCronTask(task, sysJob.getCronExpression());
    }
}

return OperationResUtils.success();

修改定时任务，先移除原来的任务，再启动新任务

boolean success = sysJobRepository.editSysJob(sysJob);
if (!success)
    return OperationResUtils.fail("编辑失败");
else {
    //先移除再添加
    if (existedSysJob.getJobStatus().equals(SysJobStatus.NORMAL.ordinal())) {
        SchedulingRunnable task = new SchedulingRunnable(existedSysJob.getBeanName(), existedSysJob.getMethodName(), existedSysJob.getMethodParams());
        cronTaskRegistrar.removeCronTask(task);
    }

    if (sysJob.getJobStatus().equals(SysJobStatus.NORMAL.ordinal())) {
        SchedulingRunnable task = new SchedulingRunnable(sysJob.getBeanName(), sysJob.getMethodName(), sysJob.getMethodParams());
        cronTaskRegistrar.addCronTask(task, sysJob.getCronExpression());
    }
}

return OperationResUtils.success();

删除定时任务

boolean success = sysJobRepository.deleteSysJobById(req.getJobId());
if (!success)
    return OperationResUtils.fail("删除失败");
else{
    if (existedSysJob.getJobStatus().equals(SysJobStatus.NORMAL.ordinal())) {
        SchedulingRunnable task = new SchedulingRunnable(existedSysJob.getBeanName(), existedSysJob.getMethodName(), existedSysJob.getMethodParams());
        cronTaskRegistrar.removeCronTask(task);
    }
}

return OperationResUtils.success();

定时任务启动/停止状态切换

if (existedSysJob.getJobStatus().equals(SysJobStatus.NORMAL.ordinal())) {
    SchedulingRunnable task = new SchedulingRunnable(existedSysJob.getBeanName(), existedSysJob.getMethodName(), existedSysJob.getMethodParams());
    cronTaskRegistrar.addCronTask(task, existedSysJob.getCronExpression());
} else {
    SchedulingRunnable task = new SchedulingRunnable(existedSysJob.getBeanName(), existedSysJob.getMethodName(), existedSysJob.getMethodParams());
    cronTaskRegistrar.removeCronTask(task);
}

添加实现了CommandLineRunner接口的SysJobRunner类，当spring boot项目启动完成后，加载数据库里状态为正常的定时任务。

@Service
public class SysJobRunner implements CommandLineRunner {

    private static final Logger logger = LoggerFactory.getLogger(SysJobRunner.class);

    @Autowired
    private ISysJobRepository sysJobRepository;

    @Autowired
    private CronTaskRegistrar cronTaskRegistrar;

    @Override
    public void run(String... args) {
        // 初始加载数据库里状态为正常的定时任务
        List<SysJobPO> jobList = sysJobRepository.getSysJobListByStatus(SysJobStatus.NORMAL.ordinal());
        if (CollectionUtils.isNotEmpty(jobList)) {
            for (SysJobPO job : jobList) {
                SchedulingRunnable task = new SchedulingRunnable(job.getBeanName(), job.getMethodName(), job.getMethodParams());
                cronTaskRegistrar.addCronTask(task, job.getCronExpression());
            }

            logger.info("定时任务已加载完毕...");
        }
    }
}

工具类SpringContextUtils，用来从spring容器里获取bean

@Component
public class SpringContextUtils implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext)
            throws BeansException {
        SpringContextUtils.applicationContext = applicationContext;
    }

    public static Object getBean(String name) {
        return applicationContext.getBean(name);
    }

    public static <T> T getBean(Class<T> requiredType) {
        return applicationContext.getBean(requiredType);
    }

    public static <T> T getBean(String name, Class<T> requiredType) {
        return applicationContext.getBean(name, requiredType);
    }

    public static boolean containsBean(String name) {
        return applicationContext.containsBean(name);
    }

    public static boolean isSingleton(String name) {
        return applicationContext.isSingleton(name);
    }

    public static Class<? extends Object> getType(String name) {
        return applicationContext.getType(name);
    }
}

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