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spring 定时任务@Scheduled详解

时间:2020-11-01 14:40:58 | 栏目:JAVA代码 | 点击:

一、配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns:task="http://www.springframework.org/schema/task"
 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.1.xsd
 http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task.xsd"
 default-autowire="byName" default-lazy-init="false">

 <!-- 定时任务相关配置 -->
 <task:executor id="executor" pool-size="10" queue-capacity="128"/>
 <task:scheduler id="scheduler" pool-size="10"/>
 <task:annotation-driven executor="executor" scheduler="scheduler" proxy-target-class="true"/>

</beans>

二、调用

有两种使用方式

1)如果需要以固定速率执行,只要将注解中指定的属性名称改成fixedRate即可,以下方法将以一个固定速率5s来调用一次执行,这个周期是以上一个任务开始时间为基准,从上一任务开始执行后5s再次调用:

@Scheduled(fixedDelay = 5000)
 public void testTask() {
  logger.info("测试定时任务");
 }

 2)使用cron表达式,可以实现定时调用如:每天凌晨调用,详细的cron相关参数见后面介绍

@Scheduled(cron = "cron = "0 0 2 * * ?"")
 public void testTaskWithDate() {
  logger.info("测试2016.定时任务");
 }

 3、cron相关参数意义

一个cron表达式有至少6个(也可能7个)有空格分隔的时间元素。

按顺序依次为

其中每个元素可以是一个值(如6),一个连续区间(9-12),一个间隔时间(8-18/4)(/表示每隔4小时),一个列表(1,3,5),通配符。由于"月份中的日期"和"星期中的日期"这两个元素互斥的,必须要对其中一个设置?.

有些子表达式能包含一些范围或列表

  例如:子表达式(天(星期))可以为 “MON-FRI”,“MON,WED,FRI”,“MON-WED,SAT”

  “*”字符代表所有可能的值

  因此,“*”在子表达式(月)里表示每个月的含义,“*”在子表达式(天(星期))表示星期的每一天

 

  “/”字符用来指定数值的增量

  例如:在子表达式(分钟)里的“0/15”表示从第0分钟开始,每15分钟

         在子表达式(分钟)里的“3/20”表示从第3分钟开始,每20分钟(它和“3,23,43”)的含义一样


  “?”字符仅被用于天(月)和天(星期)两个子表达式,表示不指定值

  当2个子表达式其中之一被指定了值以后,为了避免冲突,需要将另一个子表达式的值设为“?”

 

  “L” 字符仅被用于天(月)和天(星期)两个子表达式,它是单词“last”的缩写

  但是它在两个子表达式里的含义是不同的。

  在天(月)子表达式中,“L”表示一个月的最后一天

  在天(星期)自表达式中,“L”表示一个星期的最后一天,也就是SAT

  如果在“L”前有具体的内容,它就具有其他的含义了

  例如:“6L”表示这个月的倒数第6天,“FRIL”表示这个月的最一个星期五

  注意:在使用“L”参数时,不要指定列表或范围,因为这会导致问题

字段 允许值 允许的特殊字符
0-59 , - * /
0-59 , - * /
小时 0-23 , - * /
日期 1-31 , - * ? / L W C
月份 1-12 或者 JAN-DEC , - * /
星期 1-7 或者 SUN-SAT , - * ? / L C #
年(可选) 留空, 1970-2099 , - * /

4、局限性――@Scheduled的cron无法指定执行的年份

即我们假如使用下面的定时任务

@Scheduled(cron = "0 18 10 * * ? 2016-2016")
  public void testTaskWithDate() {
    logger.info("测试2016.定时任务");
  }

将会报下面的错误

Cron expression must consist of 6 fields (found 7 in "0 18 10 * * ? 2016-2016")

 org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'giftReceiveRecordServiceImp' defined in URL [jar:file:/Users/zhengcanrui/WORK/git/seewoedu-train-server/train-web/target/train/WEB-INF/lib/train-server-2.0-SNAPSHOT.jar!/com/seewoedu/train/service/impl/GiftReceiveRecordServiceImp.class]: Initialization of bean failed; nested exception is java.lang.IllegalStateException: Encountered invalid @Scheduled method 'testTaskWithDate': Cron expression must consist of 6 fields (found 7 in "0 18 10 * * ? 2016-2016")
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
 at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
 at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
 at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
 at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772)
 at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:839)
 at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:538)
 at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
 at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
 at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
 at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4842)
 at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5303)
 at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
 at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
 at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
 at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
 at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1696)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:606)
 at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
 at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
 at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
 at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:484)
 at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:433)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:606)
 at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
 at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
 at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
 at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1487)
 at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:97)
 at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1328)
 at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1420)
 at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:848)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:606)
 at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:322)
 at sun.rmi.transport.Transport$2.run(Transport.java:202)
 at sun.rmi.transport.Transport$2.run(Transport.java:199)
 at java.security.AccessController.doPrivileged(Native Method)
 at sun.rmi.transport.Transport.serviceCall(Transport.java:198)
 at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:567)
 at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:828)
 at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.access$400(TCPTransport.java:619)
 at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler$1.run(TCPTransport.java:684)
 at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler$1.run(TCPTransport.java:681)
 at java.security.AccessController.doPrivileged(Native Method)
 at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:681)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
 at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalStateException: Encountered invalid @Scheduled method 'testTaskWithDate': Cron expression must consist of 6 fields (found 7 in "0 18 10 * * ? 2016-2016")
 at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.processScheduled(ScheduledAnnotationBeanPostProcessor.java:405)
 at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.postProcessAfterInitialization(ScheduledAnnotationBeanPostProcessor.java:258)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:422)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1583)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
 ... 58 more

错误原因:

/**
 * Parse the given pattern expression.
 */
private void parse(String expression) throws IllegalArgumentException {
 String[] fields = StringUtils.tokenizeToStringArray(expression, " ");
 if (fields.length != 6) {
  throw new IllegalArgumentException(String.format(""
    + "cron expression must consist of 6 fields (found %d in %s)", fields.length, expression));
 }

spring taks 不支持年位定时,它毕竟不是quartz,只是简单的定时框架,比起jdk Timer就加入了线程池而以.

但是制定到年份,会存在一个问题,就是在你在过了这个时间后再启动项目的时候,他会一直报一个memory leak的错误,大概的意思是你的定时任务将永远不会被执行,导致项目一直启动不了。

源码里的注释:

 *The pattern is a list of six single space-separated fields: representing
 * second, minute, hour, day, month, weekday. Month and weekday names can be
 * given as the first three letters of the English names.

总结

以上就是这篇文章的全部内容了,希望本文的内容对大家的学习或者工作能带来一定的帮助,如果有疑问大家可以留言交流。

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