Java定时任务

1.spring注解方式

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

缺点：修改cron表达式，要重启服务

2.动态修改cron

@Component
@EnableScheduling
public class DynamicCronTask implements SchedulingConfigurer {
    /**
     * 修改了cron表达式不能立马生效
     * 要等到前一个周期执行
     * 新的周期才能生效
     * @param scheduledTaskRegistrar
     */
    @Override
    public void configureTasks(ScheduledTaskRegistrar scheduledTaskRegistrar) {
        // 数据库或者缓存获取执行周期
        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);
            }
        });
    }
}

缺点：修改了cron表达式不能立马生效，要等到前一个周期执行触发之时，新的周期才能生效

3.动态cron，立刻生效

　　3.1依赖

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

　　3.2任务

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增加任务、删除任务、修改触发时间

public class QuartzManager {

    private static SchedulerFactory schedulerFactory = new StdSchedulerFactory();

    /** 
     * @Description: 添加一个定时任务 
     *  
     * @param jobName 任务名 
     * @param jobGroupName  任务组名 
     * @param triggerName 触发器名 
     * @param triggerGroupName 触发器组名 
     * @param jobClass  任务 
     * @param cron   时间设置，参考quartz说明文档  
     */  
    @SuppressWarnings({ "unchecked", "rawtypes" })  
    public static void addJob(String jobName, String jobGroupName, String triggerName, String triggerGroupName, Class jobClass, String cron) {
        try {  
            Scheduler sched = schedulerFactory.getScheduler();
            // 任务名，任务组，任务执行类
            JobDetail jobDetail= JobBuilder.newJob(jobClass).withIdentity(jobName, jobGroupName).build();

            // 触发器  
            TriggerBuilder<Trigger> triggerBuilder = TriggerBuilder.newTrigger();
            // 触发器名,触发器组  
            triggerBuilder.withIdentity(triggerName, triggerGroupName);
            triggerBuilder.startNow();
            // 触发器时间设定  
            triggerBuilder.withSchedule(CronScheduleBuilder.cronSchedule(cron));
            // 创建Trigger对象
            CronTrigger trigger = (CronTrigger) triggerBuilder.build();

            // 调度容器设置JobDetail和Trigger
            sched.scheduleJob(jobDetail, trigger);  

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

    /** 
     * @Description: 修改一个任务的触发时间
     *  
     * @param jobName 
     * @param jobGroupName
     * @param triggerName 触发器名
     * @param triggerGroupName 触发器组名 
     * @param cron   时间设置，参考quartz说明文档   
     */  
    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 ：调用 rescheduleJob 开始 */
                // 触发器  
                TriggerBuilder<Trigger> triggerBuilder = TriggerBuilder.newTrigger();
                // 触发器名,触发器组  
                triggerBuilder.withIdentity(triggerName, triggerGroupName);
                triggerBuilder.startNow();
                // 触发器时间设定  
                triggerBuilder.withSchedule(CronScheduleBuilder.cronSchedule(cron));
                // 创建Trigger对象
                trigger = (CronTrigger) triggerBuilder.build();
                sched.rescheduleJob(triggerKey, trigger);

                /** 方式二：先删除，然后在创建一个新的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: 移除一个任务 
     *  
     * @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);// 停止触发器  
            sched.unscheduleJob(triggerKey);// 移除触发器  
            sched.deleteJob(JobKey.jobKey(jobName, jobGroupName));// 删除任务  
        } catch (Exception e) {  
            throw new RuntimeException(e);  
        }  
    }  

    /** 
     * @Description:启动所有定时任务 
     */  
    public static void startJobs() {  
        try {  
            Scheduler sched = schedulerFactory.getScheduler();  
            sched.start();  
        } catch (Exception e) {  
            throw new RuntimeException(e);  
        }  
    }  

    /** 
     * @Description:关闭所有定时任务 
     */  
    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("【系统启动】开始(每1秒输出一次)...");
            QuartzManager.addJob(JOB_NAME, JOB_GROUP_NAME, TRIGGER_NAME, TRIGGER_GROUP_NAME, MyJob.class, "0/1 * * * * ?");

            Thread.sleep(5000L);
            System.out.println("【修改时间】开始(每5秒输出一次)...");
            QuartzManager.modifyJobTime(JOB_NAME, JOB_GROUP_NAME, TRIGGER_NAME, TRIGGER_GROUP_NAME, "0/5 * * * * ?");

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