1.spring註解方式

@Component
@EnableScheduling
public class DynamicCronTask {
    // 每隔10秒執行一次
    @Scheduled(cron = "0/10 * * * * ?")
    public void task(){
      System.out.println("running " + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));
    }
}

缺點：修改cron表示式，要重啟服務

2.動態修改cron

@Component
@EnableScheduling
 
public class DynamicCronTask implements SchedulingConfigurer {
    /**
     * 修改了cron表示式不能立馬生效
     * 要等到前一個週期執行
     * 新的週期才能生效
     * @param scheduledTaskRegistrar
     */
    @Override
    public void configureTasks(ScheduledTaskRegistrar scheduledTaskRegistrar) {
        // 資料庫或者快取獲取執行週期
        String cron = "0/5 * * * * ? ";
        scheduledTaskRegistrar.addTriggerTask(
 
new Runnable() {
            @Override
            public void run() {
                System.out.println("running " + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));
            }
        }, new Trigger() {
            @Override
            public Date nextExecutionTime(TriggerContext triggerContext) {
                
 
return new CronTrigger(cron).nextExecutionTime(triggerContext);
            }
        });
    }
}

缺點：修改了cron表示式不能立馬生效，要等到前一個週期執行觸發之時，新的週期才能生效

3.動態cron，立刻生效

　　3.1依賴

　　<!--quartz-->
    <dependency>
      <groupId>org.quartz-scheduler</groupId>
      <artifactId>quartz</artifactId>
      <version>2.3.2</version>
    </dependency>

　　3.2任務

public class MyJob implements Job {
    @Override
    public void execute(JobExecutionContext jobExecutionContext) throws JobExecutionException {
        System.out.println("running " + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));
    }
}

　　3.3Quartz增加任務、刪除任務、修改觸發時間

public class QuartzManager {

    private static SchedulerFactory schedulerFactory = new StdSchedulerFactory();

    /** 
     * @Description: 新增一個定時任務 
     *  
     * @param jobName 任務名 
     * @param jobGroupName  任務組名 
     * @param triggerName 觸發器名 
     * @param triggerGroupName 觸發器組名 
     * @param jobClass  任務 
     * @param cron   時間設定，參考quartz說明文件  
     */  
    @SuppressWarnings({ "unchecked", "rawtypes" })  
    public static void addJob(String jobName, String jobGroupName, String triggerName, String triggerGroupName, Class jobClass, String cron) {
        try {  
            Scheduler sched = schedulerFactory.getScheduler();
            // 任務名，任務組，任務執行類
            JobDetail jobDetail= JobBuilder.newJob(jobClass).withIdentity(jobName, jobGroupName).build();

            // 觸發器  
            TriggerBuilder<Trigger> triggerBuilder = TriggerBuilder.newTrigger();
            // 觸發器名,觸發器組  
            triggerBuilder.withIdentity(triggerName, triggerGroupName);
            triggerBuilder.startNow();
            // 觸發器時間設定  
            triggerBuilder.withSchedule(CronScheduleBuilder.cronSchedule(cron));
            // 建立Trigger物件
            CronTrigger trigger = (CronTrigger) triggerBuilder.build();

            // 排程容器設定JobDetail和Trigger
            sched.scheduleJob(jobDetail, trigger);  

            // 啟動  
            if (!sched.isShutdown()) {  
                sched.start();  
            }  
        } catch (Exception e) {  
            throw new RuntimeException(e);  
        }  
    }  

    /** 
     * @Description: 修改一個任務的觸發時間
     *  
     * @param jobName 
     * @param jobGroupName
     * @param triggerName 觸發器名
     * @param triggerGroupName 觸發器組名 
     * @param cron   時間設定，參考quartz說明文件   
     */  
    public static void modifyJobTime(String jobName, String jobGroupName, String triggerName, String triggerGroupName, String cron) {
        try {  
            Scheduler sched = schedulerFactory.getScheduler();  
            TriggerKey triggerKey = TriggerKey.triggerKey(triggerName, triggerGroupName);
            CronTrigger trigger = (CronTrigger) sched.getTrigger(triggerKey);  
            if (trigger == null) {  
                return;  
            }  

            String oldTime = trigger.getCronExpression();  
            if (!oldTime.equalsIgnoreCase(cron)) { 
                /** 方式一 ：呼叫 rescheduleJob 開始 */
                // 觸發器  
                TriggerBuilder<Trigger> triggerBuilder = TriggerBuilder.newTrigger();
                // 觸發器名,觸發器組  
                triggerBuilder.withIdentity(triggerName, triggerGroupName);
                triggerBuilder.startNow();
                // 觸發器時間設定  
                triggerBuilder.withSchedule(CronScheduleBuilder.cronSchedule(cron));
                // 建立Trigger物件
                trigger = (CronTrigger) triggerBuilder.build();
                sched.rescheduleJob(triggerKey, trigger);

                /** 方式二：先刪除，然後在建立一個新的Job */
                /*JobDetail jobDetail = sched.getJobDetail(JobKey.jobKey(jobName, jobGroupName));
                Class<? extends Job> jobClass = jobDetail.getJobClass();
                removeJob(jobName, jobGroupName, triggerName, triggerGroupName);
                addJob(jobName, jobGroupName, triggerName, triggerGroupName, jobClass, cron);*/
            }  
        } catch (Exception e) {  
            throw new RuntimeException(e);  
        }  
    }  

    /** 
     * @Description: 移除一個任務 
     *  
     * @param jobName 
     * @param jobGroupName 
     * @param triggerName 
     * @param triggerGroupName 
     */  
    public static void removeJob(String jobName, String jobGroupName,  
            String triggerName, String triggerGroupName) {  
        try {  
            Scheduler sched = schedulerFactory.getScheduler();  

            TriggerKey triggerKey = TriggerKey.triggerKey(triggerName, triggerGroupName);

            sched.pauseTrigger(triggerKey);// 停止觸發器  
            sched.unscheduleJob(triggerKey);// 移除觸發器  
            sched.deleteJob(JobKey.jobKey(jobName, jobGroupName));// 刪除任務  
        } catch (Exception e) {  
            throw new RuntimeException(e);  
        }  
    }  

    /** 
     * @Description:啟動所有定時任務 
     */  
    public static void startJobs() {  
        try {  
            Scheduler sched = schedulerFactory.getScheduler();  
            sched.start();  
        } catch (Exception e) {  
            throw new RuntimeException(e);  
        }  
    }  

    /** 
     * @Description:關閉所有定時任務 
     */  
    public static void shutdownJobs() {  
        try {  
            Scheduler sched = schedulerFactory.getScheduler();  
            if (!sched.isShutdown()) {  
                sched.shutdown();  
            }  
        } catch (Exception e) {  
            throw new RuntimeException(e);  
        }  
    }  
}

public class MyQuartz {
    public static String JOB_NAME = "JOB";
    public static String TRIGGER_NAME = "TRIGGER";
    public static String JOB_GROUP_NAME = "JOB_GROUP";
    public static String TRIGGER_GROUP_NAME = "TRIGGER_GROUP";
    public static void main(String[] args) {
        try {
            System.out.println("【系統啟動】開始(每1秒輸出一次)...");
            QuartzManager.addJob(JOB_NAME, JOB_GROUP_NAME, TRIGGER_NAME, TRIGGER_GROUP_NAME, MyJob.class, "0/1 * * * * ?");

            Thread.sleep(5000L);
            System.out.println("【修改時間】開始(每5秒輸出一次)...");
            QuartzManager.modifyJobTime(JOB_NAME, JOB_GROUP_NAME, TRIGGER_NAME, TRIGGER_GROUP_NAME, "0/5 * * * * ?");

            Thread.sleep(15 * 1000L);
            System.out.println("【移除定時】開始...");
            QuartzManager.removeJob(JOB_NAME, JOB_GROUP_NAME, TRIGGER_NAME, TRIGGER_GROUP_NAME);
            System.out.println("【移除定時】成功");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}