基于注解（@Scheduled）

配置类

@Configuration        //标记配置类
@EnableScheduling       //开启定时任务
public class MyScheduleConfig {
    //添加定时任务
    @Scheduled(cron = "0/5 * * * * ?") // 每5秒执行一次 
    private void myTasks() {
        System.out.println("执行定时任务 " + LocalDateTime.now());
    }
}

查看cron表达式

启动应用，控制台看效果

简单方便

缺点：修改定时任务的执行周期或者停止时，需要修改代码，重启。

数据库动态配置

添加MySQL表

CREATE TABLE `scheduled_job` (
  `job_id` int(11) NOT NULL AUTO_INCREMENT COMMENT '主键id',
  `job_key` varchar(128) NOT NULL COMMENT '定时任务完整类名',
  `cron_expression` varchar(20) NOT NULL COMMENT 'cron表达式',
  `task_explain` varchar(50) NOT NULL DEFAULT '' COMMENT '任务描述',
  `status` tinyint(4) NOT NULL DEFAULT '1' COMMENT '状态,1:正常;-1:停用',
  PRIMARY KEY (`job_id`),
  UNIQUE KEY `job_key` (`job_key`),
  UNIQUE KEY `cron_key_unique_idx` (`job_key`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8 COLLATE=utf8_bin COMMENT='定时任务表';

插入两条数据，job_key是完整的类名

创建定时任务线程池

@Configuration
@Slf4j
public class ScheduledConfig {
    @Bean
    public ThreadPoolTaskScheduler threadPoolTaskScheduler() {
        log.info("创建定时任务调度线程池 start");
        ThreadPoolTaskScheduler threadPoolTaskScheduler = new ThreadPoolTaskScheduler();
        threadPoolTaskScheduler.setPoolSize(20);
        threadPoolTaskScheduler.setThreadNamePrefix("taskExecutor-");
        threadPoolTaskScheduler.setWaitForTasksToCompleteOnShutdown(true);
        threadPoolTaskScheduler.setAwaitTerminationSeconds(60);
        log.info("创建定时任务调度线程池 end");
        return threadPoolTaskScheduler;
    }
}

项目启动时初始化定时任务

@Slf4j
@Component
public class ScheduledTaskRunner implements ApplicationRunner {
    @Autowired
    private ScheduledTaskService scheduledTaskService;
    @Override
    public void run(ApplicationArguments args) throws Exception {
        log.info("----初始化定时任务开始----");
        scheduledTaskService.initTask();
        log.info("----初始化定时任务完成----");
    }
}

定时任务公共接口

public interface ScheduledOfTask extends Runnable{
    void execute();
    @Override
    default void run() {
        execute();
    }
}

创建两个定时任务实现类

@Component
@Slf4j
public class TaskJob1 implements ScheduledOfTask{
    @Override
    public void execute() {
        log.info("执行任务1 "+ LocalDateTime.now());
    }
}

@Component
@Slf4j
public class TaskJob2 implements ScheduledOfTask{
    @Override
    public void execute() {
        log.info("执行任务2 "+ LocalDateTime.now());
    }
}

定时任务管理接口

public interface ScheduledTaskService{
    Boolean start(ScheduledJob scheduledJob);
    Boolean stop(String jobKey);
    Boolean restart(ScheduledJob scheduledJob);
    void initTask();
}

定时任务管理实现类

@Slf4j
@Service
public class ScheduledTaskServiceImpl implements ScheduledTaskService {
    /**
     * 可重入锁
     */
    private ReentrantLock lock = new ReentrantLock();
    /**
     * 定时任务线程池
     */
    @Autowired
    private ThreadPoolTaskScheduler threadPoolTaskScheduler;
    /**
     * 启动状态的定时任务集合
     */
    public Map scheduledFutureMap = new ConcurrentHashMap<>();
    @Autowired
    private ScheduledJobService scheduledJobService;
    @Override
    public Boolean start(ScheduledJob scheduledJob) {
        String jobKey = scheduledJob.getJobKey();
        log.info("启动定时任务"+jobKey);
        //添加锁放一个线程启动，防止多人启动多次
        lock.lock();
        log.info("加锁完成");
        try {
            if(this.isStart(jobKey)){
                log.info("当前任务在启动状态中");
                return false;
            }
            //任务启动
            this.doStartTask(scheduledJob);
        } finally {
            lock.unlock();
            log.info("解锁完毕");
        }
        return true;
    }
    /**
     * 任务是否已经启动
     */
    private Boolean isStart(String taskKey) {
        //校验是否已经启动
        if (scheduledFutureMap.containsKey(taskKey)) {
            if (!scheduledFutureMap.get(taskKey).isCancelled()) {
                return true;
            }
        }
        return false;
    }
    @Override
    public Boolean stop(String jobKey) {
        log.info("停止任务 "+jobKey);
        boolean flag = scheduledFutureMap.containsKey(jobKey);
        log.info("当前实例是否存在 "+flag);
        if(flag){
            ScheduledFuture scheduledFuture = scheduledFutureMap.get(jobKey);
            scheduledFuture.cancel(true);
            scheduledFutureMap.remove(jobKey);
        }
        return flag;
    }
    @Override
    public Boolean restart(ScheduledJob scheduledJob) {
        log.info("重启定时任务"+scheduledJob.getJobKey());
        //停止
        this.stop(scheduledJob.getJobKey());
        return this.start(scheduledJob);
    }
    /**
     * 执行启动任务
     */
    public void doStartTask(ScheduledJob sj){
        log.info(sj.getJobKey());
        if(sj.getStatus().intValue() != 1)
            return;
        Class clazz;
        ScheduledOfTask task;
        try {
            clazz = Class.forName(sj.getJobKey());
            task = (ScheduledOfTask) SpringContextUtil.getBean(clazz);
        } catch (ClassNotFoundException e) {
            throw new IllegalArgumentException("spring_scheduled_cron表数据" + sj.getJobKey() + "有误", e);
        }
        Assert.isAssignable(ScheduledOfTask.class, task.getClass(), "定时任务类必须实现ScheduledOfTask接口");
        ScheduledFuture scheduledFuture = threadPoolTaskScheduler.schedule(task,(triggerContext -> new CronTrigger(sj.getCronExpression()).nextExecutionTime(triggerContext)));
        scheduledFutureMap.put(sj.getJobKey(),scheduledFuture);
    }
    @Override
    public void initTask() {
        List list = scheduledJobService.list();
        for (ScheduledJob sj : list) {
            if(sj.getStatus().intValue() == -1) //未启用
                continue;
            doStartTask(sj);
        }
    }
}

获取Bean的工具类SpringContextUtil

@Component
public class SpringContextUtil implements ApplicationContextAware {
    private static ApplicationContext applicationContext = null;
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        if(SpringContextUtil.applicationContext == null){
            SpringContextUtil.applicationContext  = applicationContext;
        }
    }
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }
    public static Object getBean(String name){
        return getApplicationContext().getBean(name);
    }
    public static  T getBean(Class clazz){
        return getApplicationContext().getBean(clazz);
    }
    public static  T getBean(String name,Class clazz){
        return getApplicationContext().getBean(name, clazz);
    }
}

表操作

@Data
@TableName("scheduled_job")
public class ScheduledJob {
    @TableId(value = "job_id",type = IdType.AUTO)
    private Integer jobId;
    private String jobKey;
    private String cronExpression;
    private String taskExplain;
    private Integer status;
}

public interface ScheduledJobMapper extends BaseMapper {
}

public interface ScheduledJobService extends IService {
    /**
     * 修改定时任务，并重新启动
     * @param scheduledJob
     * @return
     */
    boolean updateOne(ScheduledJob scheduledJob);
}

@Service
@Slf4j
public class ScheduledJobServiceImpl extends ServiceImpl implements ScheduledJobService{
    @Autowired
    private ScheduledTaskService scheduledTaskService;
    @Override
    public boolean updateOne(ScheduledJob scheduledJob) {
        if(updateById(scheduledJob))
            scheduledTaskService.restart(getById(scheduledJob.getJobId()));
        return true;
    }
}

修改定时任务的接口

@RestController
@RequestMapping("/job")
public class ScheduledJobController {
    @Autowired
    private ScheduledJobService scheduledJobService;
    @PostMapping(value = "/update")
    public CallBackResult update(HttpServletRequest request, ScheduledJob scheduledJob){
         if(scheduledJobService.updateOne(scheduledJob))
             return new CallBackResult(true,"修改成功");
         return new CallBackResult(false,"修改失败");
    }
}