Spring Task Scheduling: XML and Annotation Configurations with Cron Expressions

Spring provides built‑in support for scheduled tasks, and this article shows how to use Spring Task (a lightweight alternative to Quartz) with both XML‑based and annotation‑based configurations.

1. XML configuration method

First, create a simple POJO class that contains the task method:

package com.aflyun.web.task;

import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;

@Component
//@Service also works
public class TaskCool {
    /**
     * First timer test method
     */
    public void testJob() {
        System.out.println("test first taskJob .... ");
    }
}

Then configure applicationContext.xml with the required namespaces and a task:scheduled-tasks element:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:task="http://www.springframework.org/schema/task"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd
           http://www.springframework.org/schema/tx
           http://www.springframework.org/schema/tx/spring-tx.xsd
           http://www.springframework.org/schema/aop
           http://www.springframework.org/schema/aop/spring-aop.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context.xsd
           http://www.springframework.org/schema/task 
           http://www.springframework.org/schema/task/spring-task.xsd">

    <context:component-scan base-package="com.aflyun.web" />
    <aop:aspectj-autoproxy proxy-target-class="true" />
    <context:annotation-config />
    <!-- In applicationContext.xml configure the scheduled task -->
    <!-- ref: POJO name, method: method name, cron: cron expression -->
    <task:scheduled-tasks>
        <task:scheduled ref="taskCool" method="testJob" cron="0/5 * * * * ?" />
    </task:scheduled-tasks>
</beans>

Note that the task namespace and schema must be added to the configuration file, and the ref attribute defaults to the bean name (the class name with a lower‑case first letter).

2. Annotation‑based method

Using @Scheduled eliminates the need for XML entries for each task. The annotation definition in Spring looks like this:

@Target({java.lang.annotation.ElementType.METHOD, java.lang.annotation.ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Scheduled {
    public abstract String cron();
    public abstract long fixedDelay();
    public abstract long fixedRate();
}

Key attributes:

cron – a cron expression that defines the schedule.

fixedDelay – interval in milliseconds between the end of the previous execution and the start of the next.

fixedRate – interval in milliseconds between the start of successive executions.

Example POJO using the annotation:

package com.tclshop.cms.center.web.task;

import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
public class WebTask {
    // Execute every 5 seconds
    @Scheduled(cron = "0/5 * * * * ?")
    public void TaskJob() {
        System.out.println("test second annotation style ...");
    }
}

To enable annotation processing, add the following to applicationContext.xml:

<!-- Enable @Scheduled processing -->
<task:annotation-driven scheduler="qbScheduler" mode="proxy" />
<task:scheduler id="qbScheduler" pool-size="10" />

Only the task:annotation-driven line is strictly required; other parameters are optional.

3. Cron expression reference

The cron fields and allowed values are:

Field   Allowed values   Special characters
Second   0-59             , - * /
Minute   0-59             , - * /
Hour     0-23             , - * /
Day      1-31             , - * ? / L W C
Month    1-12 or JAN-DEC , - * /
Weekday  1-7 or SUN-SAT  , - * ? / L C #
Year (optional) 1970-2099 , - * /

Common examples:

"0 0 12 * * ?"          – every day at 12:00 PM
"0 15 10 ? * *"        – every day at 10:15 AM
"0 0/5 14 * * ?"       – every 5 minutes between 2 PM and 2:55 PM
"0 10,44 14 ? 3 WED"   – at 14:10 and 14:44 on every Wednesday in March
"0 15 10 ? * MON-FRI"  – at 10:15 AM Monday through Friday

4. Summary

Spring’s task scheduling can be set up quickly with either XML configuration or the more concise @Scheduled annotation, both supporting flexible cron expressions without requiring external libraries.

References

Spring scheduled task implementations – http://gong1208.iteye.com/blog/1773177

Cron expression guide for Spring – http://www.cnblogs.com/xiaopeng84/archive/2009/11/26/1611427.html

Quartz cron expression details – http://www.cnblogs.com/sunjie9606/archive/2012/03/15/2397626.html

Original article: blog.csdn.net/u010648555/article/details/52162840