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。

添加执行定时任务的线程池配置类


@Configurationpublic 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。


@Componentpublic class CronTaskRegistrar implements DisposableBean {
    private final Map 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


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。


@Servicepublic 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 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


@Componentpublic 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 getBean(Class requiredType) {        return applicationContext.getBean(requiredType);    }
    public static  T getBean(String name, Class 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 getType(String name) {        return applicationContext.getType(name);    }}