首先,废话两句楼主是在开发中遇到具体需求,要用到定时器,那么大致说下两种定时器:
定时器 | Quartz | TimerTask |
---|---|---|
执行时间 | 可以通过cron表达式精确到特定时间执行 | TimerTask不能 |
效率 | 每次执行任务都创建一个新的任务类对象 | 每次使用同一个任务类对象 |
对异常的处理 | 不会因为异常,而导致定时器关闭,不再执行循环任务。 | 抛出异常后,再也没有执行此任务了,并且定时器所在的线程也自动结束 |
消耗内存 | 大于TimerTask | 小于Quartz |
使用 | 整合使用,使用简单。 | 一旦出现异常,需要在异常的时候重构事务,需要工厂模式and代理模式的加入。 |
可以根据自己的水平 and 需求选择一个合适自己的上手。下面我们上干货。
PS:Quartz 会产生内存溢出的问题,楼主还没有仔细研究,有兴趣的同学可以研究下,欢迎给我的邮箱([email protected])发邮件一起探讨。
开发环境:Spring boot + Maven + mybatis 。
开发工具:idea
① 那么我们首先看需要的包,先看看pom.xml文件:
<dependency>
<groupId>org.quartz-scheduler</groupId>
<artifactId>quartz</artifactId>
<version>2.2.1</version>
</dependency>
<dependency><!-- 该依赖必加,里面有sping对schedule的支持 -->
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
</dependency>
我只截取了部分,除了这些以外,如果你是spring boot 的项目一定还要有相关配置文件,别指望我会贴出来,做梦!摔!
② 先写一个监听器保证项目启动的时候会调用到,我们的定时任务,代码如下:
package task;
import org.quartz.SchedulerException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationListener;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.scheduling.quartz.SchedulerFactoryBean;
/**
* @author Lucky
* @Description 监听器
* @Date 15:08 2018/5/23
* @Param
* @return
**/
@Configuration
public class SchedulerListener implements ApplicationListener<ContextRefreshedEvent> {
@Autowired
public MyScheduler myScheduler;
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
try {
myScheduler.scheduleJobs();
} catch (SchedulerException e) {
e.printStackTrace();
}
}
@Bean
public SchedulerFactoryBean schedulerFactoryBean() {
SchedulerFactoryBean schedulerFactoryBean = new SchedulerFactoryBean();
return schedulerFactoryBean;
}
}
③ 写我们自己的定时器,用来触发我们的任务:
package task;
import org.quartz.CronScheduleBuilder;
import org.quartz.CronTrigger;
import org.quartz.JobBuilder;
import org.quartz.JobDetail;
import org.quartz.JobKey;
import org.quartz.Scheduler;
import org.quartz.SchedulerException;
import org.quartz.TriggerBuilder;
import org.quartz.TriggerKey;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.quartz.SchedulerFactoryBean;
import org.springframework.stereotype.Component;
/**
* @author Lucky
* @Description
* @Date 13:48 2018/5/16
* @Param
* @return
**/
@Component
public class MyScheduler {
@Autowired
SchedulerFactoryBean schedulerFactoryBean;
static Scheduler scheduler;
public void scheduleJobs() throws SchedulerException {
scheduler = schedulerFactoryBean.getScheduler();
startJob1(); // 每5分钟执行一次
startJob2(); // 每2分钟执行一次
}
public static void startJob1() throws SchedulerException {
JobDetail jobDetail = JobBuilder.newJob(ScheduledJob.class).withIdentity("job1", "group1").build();
CronScheduleBuilder scheduleBuilder = CronScheduleBuilder.cronSchedule("0/5 * * * * ?");
CronTrigger cronTrigger = TriggerBuilder.newTrigger().withIdentity("trigger1", "group1")
.withSchedule(scheduleBuilder).build();
scheduler.scheduleJob(jobDetail, cronTrigger);
}
public static void modifyJob1(String cron) throws SchedulerException {
TriggerKey triggerKey = TriggerKey.triggerKey("trigger1", "group1");
CronScheduleBuilder scheduleBuilder = CronScheduleBuilder.cronSchedule(cron);
CronTrigger newTrigger = TriggerBuilder.newTrigger().withIdentity("trigger1", "group1")
.withSchedule(scheduleBuilder).build();
scheduler.rescheduleJob(triggerKey, newTrigger);
}
public static String getJob1Status() throws SchedulerException {
TriggerKey triggerKey = TriggerKey.triggerKey("trigger1", "group1");
return scheduler.getTriggerState(triggerKey).name();
}
public static void pauseJob1() throws SchedulerException {
scheduler.pauseJob(JobKey.jobKey("job1", "group1"));
}
public static void resumeJob1() throws SchedulerException {
scheduler.resumeJob(JobKey.jobKey("job1", "group1"));
}
private void startJob2() throws SchedulerException {
JobDetail jobDetail = JobBuilder.newJob(ScheduledJob2.class).withIdentity("job2", "group1").build();
CronScheduleBuilder scheduleBuilder = CronScheduleBuilder.cronSchedule("0/2 * * * * ?");
CronTrigger cronTrigger = TriggerBuilder.newTrigger().withIdentity("trigger2", "group1")
.withSchedule(scheduleBuilder).build();
scheduler.scheduleJob(jobDetail, cronTrigger);
}
public static void modifyJob2(String cron) throws SchedulerException {
TriggerKey triggerKey = TriggerKey.triggerKey("trigger2", "group1");
CronScheduleBuilder scheduleBuilder = CronScheduleBuilder.cronSchedule(cron);
CronTrigger newTrigger = TriggerBuilder.newTrigger().withIdentity("trigger2", "group1")
.withSchedule(scheduleBuilder).build();
scheduler.rescheduleJob(triggerKey, newTrigger);
}
public static String getJob2Status() throws SchedulerException {
TriggerKey triggerKey = TriggerKey.triggerKey("trigger2", "group1");
return scheduler.getTriggerState(triggerKey).name();
}
public static void pauseJob2() throws SchedulerException {
scheduler.pauseJob(JobKey.jobKey("job2", "group1"));
}
public static void resumeJob2() throws SchedulerException {
scheduler.resumeJob(JobKey.jobKey("job2", "group1"));
}
}
④ 接下来就写我们具体的任务如下:
第一个定时任务
package task;
import org.quartz.Job;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;
import java.util.Date;
/**
* @ClassName ScheduledJob
* @Description TODO
* @Author Lucky
* @Date 2018/5/16 13:46
* @Version 1.0
*/
public class ScheduledJob implements Job {
@Override
public void execute(JobExecutionContext context) throws JobExecutionException {
System.out.println("第一个定时任务" + new Date());
}
}
第二个定时任务
package task;
import org.quartz.Job;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;
import java.util.Date;
/**
* @ClassName ScheduledJob2
* @Description TODO
* @Author Lucky
* @Date 2018/5/16 13:47
* @Version 1.0
*/
public class ScheduledJob2 implements Job {
@Override
public void execute(JobExecutionContext context) throws JobExecutionException {
System.out.println("第二个定时任务" + new Date());
}
}
启动测试Demo(启动方法main直接写在了Controller里面,配个spring boot 注解@SpringBootApplication):
package task;
import org.quartz.SchedulerException;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
/**
* @author Lucky
* @Description 测试定时任务,启动类
* @Date 15:12 2018/5/23
* @Param
* @return
**/
@RestController
@SpringBootApplication
public class ScheduleController {
@RequestMapping("/modify")
public @ResponseBody String modify() throws SchedulerException {
MyScheduler.modifyJob1("0/1 * * * * ?");
return "1";
}
@RequestMapping("/status")
public @ResponseBody String status() throws SchedulerException {
return MyScheduler.getJob1Status();
}
@RequestMapping("/pause")
public @ResponseBody String pause() throws SchedulerException {
MyScheduler.pauseJob1();
return "1";
}
@RequestMapping("/resume")
public @ResponseBody String resume() throws SchedulerException {
MyScheduler.resumeJob1();
return "1";
}
public static void main(String[] args) {
SpringApplication.run(ScheduleController.class, args);
}
}
如果你在定时任务里,涉及到业务逻辑,需要查表用到service的对象,如果你直接在任务类里面通过注解的方式注入,比如:
@Autowired
private TestService service;
你会发现全部都是java.lang.NullPointerException,
那么怎么解决看这里,
我爱你
后来光阴单薄
年月时日都从肩头剥落
你当然可以忘记我
可答应我别忘记那年盛夏
我们哭着拥抱
承诺彼此
再也不难过