spring cron 定时任务

文章首发于个人博客：https://yeyouluo.github.io

0 预备知识：cron表达式

见《5 参考》一节。

1 环境

eclipse mars2 + Maven3.3.9

2 开发步骤

项目码云地址

2.1 建立一个maven工程

POM如下：

 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

   <modelVersion>4.0.0</modelVersion>

   <groupId>com.yeyouluo.spring.timer</groupId>

   <artifactId>spring-timer-demo</artifactId>

   <version>0.0.1-SNAPSHOT</version>

   <properties>

         <spring.version>4.2.6.RELEASE</spring.version>

         <slf4j.version>1.7.2</slf4j.version>

         <log4j.version>1.2.17</log4j.version>

     </properties>

     <dependencies>

         <dependency>

             <groupId>org.slf4j</groupId>

             <artifactId>slf4j-api</artifactId>

             <version>${slf4j.version}</version>

         </dependency>

         <dependency>

             <groupId>org.slf4j</groupId>

             <artifactId>slf4j-log4j12</artifactId>

             <version>${slf4j.version}</version>

         </dependency>

         <!-- common-logging 实际调用slf4j -->

         <dependency>

             <groupId>org.slf4j</groupId>

             <artifactId>jcl-over-slf4j</artifactId>

             <version>${slf4j.version}</version>

         </dependency>

         <!-- java.util.logging 实际调用slf4j -->

         <dependency>

             <groupId>org.slf4j</groupId>

             <artifactId>jul-to-slf4j</artifactId>

             <version>${slf4j.version}</version>

         </dependency>

         <dependency>

             <groupId>log4j</groupId>

             <artifactId>log4j</artifactId>

             <version>${log4j.version}</version>

         </dependency>

         <dependency>

             <groupId>org.lazyluke</groupId>

             <artifactId>log4jdbc-remix</artifactId>

             <version>0.2.7</version>

         </dependency>

         <!-- spring核心包 -->

         <dependency>

             <groupId>org.springframework</groupId>

             <artifactId>spring-core</artifactId>

             <version>${spring.version}</version>

         </dependency>

         <dependency>

             <groupId>org.springframework</groupId>

             <artifactId>spring-web</artifactId>

             <version>${spring.version}</version>

         </dependency>

         <dependency>

             <groupId>org.springframework</groupId>

             <artifactId>spring-tx</artifactId>

             <version>${spring.version}</version>

         </dependency>

         <dependency>

             <groupId>org.springframework</groupId>

             <artifactId>spring-jdbc</artifactId>

             <version>${spring.version}</version>

         </dependency>

         <dependency>

             <groupId>org.springframework</groupId>

             <artifactId>spring-webmvc</artifactId>

             <version>${spring.version}</version>

         </dependency>

         <dependency>

             <groupId>org.springframework</groupId>

             <artifactId>spring-aop</artifactId>

             <version>${spring.version}</version>

         </dependency>

         <dependency>

             <groupId>org.springframework</groupId>

             <artifactId>spring-beans</artifactId>

             <version>${spring.version}</version>

         </dependency>

         <dependency>

             <groupId>org.springframework</groupId>

             <artifactId>spring-context</artifactId>

             <version>${spring.version}</version>

         </dependency>

         <dependency>

             <groupId>org.springframework</groupId>

             <artifactId>spring-context-support</artifactId>

             <version>${spring.version}</version>

         </dependency>

         <dependency>

             <groupId>org.springframework</groupId>

             <artifactId>spring-expression</artifactId>

             <version>${spring.version}</version>

         </dependency>

         <dependency>

               <groupId>org.springframework</groupId>

               <artifactId>spring-messaging</artifactId>

               <version>${spring.version}</version>

         </dependency>

         <dependency>

              <groupId>org.springframework.integration</groupId>

               <artifactId>spring-integration-core</artifactId>

               <version>4.2.5.RELEASE</version>

         </dependency>

     </dependencies>

     <packaging>jar</packaging>

 </project>

POM.xml

2.2 添加配置文件

①log4j.properties

 log4j.rootLogger=INFO, Console, RollingFile

 #Console

 log4j.appender.Console=org.apache.log4j.ConsoleAppender

 log4j.appender.Console.layout=org.apache.log4j.PatternLayout

 log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n

 #RollingFile

 log4j.appender.RollingFile=org.apache.log4j.DailyRollingFileAppender

 log4j.appender.RollingFile.File=logs/log.log

 log4j.appender.RollingFile.layout=org.apache.log4j.PatternLayout

 log4j.appender.RollingFile.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n

log4j.xml

②spring-base.xml

 <?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"

 xmlns:context="http://www.springframework.org/schema/context"

 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd

 http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.0.xsd

 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

 <bean id="readDBTask" class="com.yeyouluo.spring.timer.service.ReadDBTask"></bean>

 <task:scheduled-tasks>

 <task:scheduled ref="readDBTask" method="doSomething" cron="0/3 * * * * ?"/>

 </task:scheduled-tasks>

 </beans>

spring-base.xml

2.3 创建定时任务ReadDBTask

 package com.yeyouluo.spring.timer.service;

 import org.apache.log4j.Logger;

 public class ReadDBTask {

     public static Logger log = Logger.getLogger(ReadDBTask.class);

     public void doSomething() {

         log.info("********");

         log.info("定时任务执行。");

     }

 }

ReadDBTask.java

2.4 添加启动函数Main

 package com.yeyouluo.spring.timer.start;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 import org.springframework.context.support.ClassPathXmlApplicationContext;

 public class Main {

     public static Logger logger = LoggerFactory.getLogger(Main.class);

     public static final String config = "spring-base.xml";

     public static void main(String[] args) {

         ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext(config);

         logger.info("spring timer started");

         if( ctx != null ) {

             ctx.start();

         }

     }

 }

Main.java

3 流程分析

在启动函数Main.java右键 –> run as –> Java Application。
结果为：每3秒在控制台输出如下：
2017-10-16 15:03:54,885 [main] INFO [com.yeyouluo.spring.timer.start.Main] - spring timer started
2017-10-16 15:03:57,002 [pool-1-thread-1] INFO [com.yeyouluo.spring.timer.service.ReadDBTask] - **
2017-10-16 15:03:57,003 [pool-1-thread-1] INFO [com.yeyouluo.spring.timer.service.ReadDBTask] - 定时任务执行。
2017-10-16 15:04:00,001 [pool-1-thread-1] INFO [com.yeyouluo.spring.timer.service.ReadDBTask] - **
2017-10-16 15:04:00,001 [pool-1-thread-1] INFO [com.yeyouluo.spring.timer.service.ReadDBTask] - 定时任务执行。
2017-10-16 15:04:03,001 [pool-1-thread-1] INFO [com.yeyouluo.spring.timer.service.ReadDBTask] - **
2017-10-16 15:04:03,001 [pool-1-thread-1] INFO [com.yeyouluo.spring.timer.service.ReadDBTask] - 定时任务执行。
2017-10-16 15:04:06,002 [pool-1-thread-1] INFO [com.yeyouluo.spring.timer.service.ReadDBTask] - **
2017-10-16 15:04:06,002 [pool-1-thread-1] INFO [com.yeyouluo.spring.timer.service.ReadDBTask] - 定时任务执行。

从入口函数开始，加载spring配置文件spring-base.xml。
spring-base.xml定义了，指向定时任务类com.yeyouluo.spring.timer.service.ReadDBTask的doSomething方法。
执行doSomething方法中的逻辑。

4 拓展：打成jar部署到单独的服务器上

目标：用java命令拉起程序。
步骤：
①将依赖jar提取出来，放入D:\timer\lib
②maven打包程序，将生成的jar放入D:\timer\lib
③在D:\timer\lib下新建一个文件start.cmd，内容如下：
java -Djava.ext.dirs=D:\timer\lib -Xms1024m -Xmx1024m com.yeyouluo.spring.timer.start.Main
④双击start.cmd。
结果：
spring cron 定时任务-LMLPHP