【1】java.util.Timer
Timer中主要有两种实现方法:schedule和scheduleAtFixedRate。
① schedule
new Timer("testTimer").schedule(new TimerTask() {
@Override
public void run() {
System.out.println("TimerTask");
}
}, 1000,2000);
解释:1000ms是延迟启动时间,2000ms是定时任务周期,每2s执行一次
② scheduleAtFixedRate
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
try {
Date date = dateFormat.parse("2019-07-11 12:00:00.000");
new Timer("testTimer1").scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
System.out.println("TimerTask");
}
}, date,2000);
} catch (ParseException e) {
e.printStackTrace();
}
解释:date是开始时间,2000ms是定时任务周期,每2s执行一次。
Timer中的schedule和scheduleAtFixedRate,前者会等任务结束在开始计算时间间隔,后者是在任务开始就计算时间,有并发的情况
【2】java.util.concurrent.ScheduledExecutorService
关于这个参考博文:
多线程并发之线程池Executor与Fork/Join框架
SpirngBoot - 定时任务入门(@Scheduled )详解
【3】SpringTask
① 任务类
@Service
public class SpringTask {
private static final Logger log = LoggerFactory.getLogger(SpringTask.class);
@Scheduled(cron = "1/5 * * * * *")
public void task1(){
log.info("springtask 定时任务!");
}
@Scheduled(initialDelay = 1000,fixedRate = 1*1000)
public void task2(){
log.info("springtask 定时任务!");
}
}
② 配置文件修改
1.简单版
<task:annotation-driven/>
2.任务池版
<task:executor id="executor" pool-size="10" />
<task:scheduler id="scheduler" pool-size="10" />
<task:annotation-driven executor="executor" scheduler="scheduler" />
3.解释
假如只有一个定时任务,可以用简单版;如果有多个定时任务,则要用任务池,不然它会顺序执行。
两个任务的时间间隔为:执行时间+设定的定时间隔。
例子:(这个任务8s执行一次)
@Scheduled(cron = "1/4 * * * * *")
public void task2(){
log.info("springtask 定时任务2!");
try {
TimeUnit.SECONDS.sleep(4);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
关于这个在SpringBoot中同样提供了@Scheduled注解来实现定时任务并做了自动配置,参考博文SpirngBoot - 定时任务入门(@Scheduled )详解。
【4】Quartz
① pom文件配置
<!-- quartz -->
<dependency>
<groupId>org.quartz-scheduler</groupId>
<artifactId>quartz</artifactId>
<version>2.3.0</version>
</dependency>
<!--调度器核心包-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>4.3.4.RELEASE</version>
</dependency>
② Job实现
public class HelloWorldJob implements Job {
@Override
public void execute(JobExecutionContext jobExecutionContext) throws JobExecutionException {
String strTime = new SimpleDateFormat("HH-mm-ss").format(new Date());
System.out.println( strTime + ":Hello World!");
}
}
③ 调度器(可以用listener在项目启动时执行)
public class MyScheduler {
public static void main(String[] args) throws SchedulerException {
//创建调度器Schedule
SchedulerFactory schedulerFactory = new StdSchedulerFactory();
Scheduler scheduler = schedulerFactory.getScheduler();
//创建JobDetail实例,并与HelloWordlJob类绑定
JobDetail jobDetail = JobBuilder.newJob(HelloWorldJob.class).withIdentity("job1", "jobGroup1")
.build();
//创建触发器Trigger实例(立即执行,每隔1S执行一次)
Trigger trigger = TriggerBuilder.newTrigger()
.withIdentity("trigger1", "triggerGroup1")
.startNow()
.withSchedule(SimpleScheduleBuilder.simpleSchedule().withIntervalInSeconds(1).repeatForever())
.build();
//开始执行
scheduler.scheduleJob(jobDetail, trigger);
scheduler.start();
}
}
上面用的是简单触发器,也可以用Con触发器,如下:
Trigger cronTrigger = TriggerBuilder.newTrigger()
.withIdentity("trigger2", "triggerGroup2")
.startNow()
.withSchedule(cronSchedule("0 42 10 * * ?"))
.build();
④ 整合Spring
也可以直接把上面的调度器写成配置文件,整合spring
配置文件如下:
<bean id="QuarFirstJob" class="com.quartz.QuarFirstJob" />
<bean id="jobDetail"
class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">
<property name="group" value="quartzGroup1" />
<property name="name" value="quartzJob1" />
<!--false表示等上一个任务执行完后再开启新的任务 -->
<property name="concurrent" value="false" />
<property name="targetObject">
<ref bean="QuarFirstJob" />
</property>
<property name="targetMethod">
<value>first</value>
</property>
</bean>
<!-- 调度触发器 -->
<bean id="myTrigger"
class="org.springframework.scheduling.quartz.CronTriggerFactoryBean">
<property name="name" value="trigger1" />
<property name="group" value="group1" />
<property name="jobDetail">
<ref bean="jobDetail" />
</property>
<property name="cronExpression">
<value>0/5 * * * * ?</value>
</property>
</bean>
<!-- 调度工厂 -->
<bean id="scheduler"
class="org.springframework.scheduling.quartz.SchedulerFactoryBean">
<property name="triggers">
<list>
<ref bean="myTrigger" />
</list>
</property>
</bean>