实现定时任务简单的有四种方式:Timer\ScheduledThreadPool线程池\quartz(常用)，还有另一种就是springtask。

　　都说springtask上手简单，于是简单的研究一下springtask的使用，并且运用到自己的项目中。其也有两种配置方式，第一种是基于xml配置，第二种是基于注解。

　　SprngTask没有专门的包，其核心类位于spring-context包中。所以引入spring的核心包此功能即可使用。

　　在实际的项目中，我们经常将job作为action层，在job中注入service去操作底层的dao，或者定时的向其他系统拉取数据,再或者向其他系统推送数据。

 

1.基于xml配置的简单的使用

测试类:(每五秒钟打印一次日志)

package cn.xm.exam.job;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.stereotype.Component;@Componentpublic class FirstTestJob {    private static final Logger log = LoggerFactory.getLogger(FirstTestJob.class);    private static int count;    public void cron() {        log.info("spring task execute times {}", count++);    }}

 

xml配置:(非常类似于quartz的cron表达式和linux定时的cron表达式)

 

重点是引入task的schema:

xmlns:task="http://www.springframework.org/schema/task"http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.2.xsd

 

 

结果:

... 2018-11-14 22:35:00 [cn.xm.exam.job.FirstTestJob]-[INFO] spring task execute times 592018-11-14 22:35:05 [cn.xm.exam.job.FirstTestJob]-[INFO] spring task execute times 602018-11-14 22:35:10 [cn.xm.exam.job.FirstTestJob]-[INFO] spring task execute times 612018-11-14 22:35:15 [cn.xm.exam.job.FirstTestJob]-[INFO] spring task execute times 622018-11-14 22:35:20 [cn.xm.exam.job.FirstTestJob]-[INFO] spring task execute times 632018-11-14 22:35:25 [cn.xm.exam.job.FirstTestJob]-[INFO] spring task execute times 64...

 

 

 

2.基于注解的使用

首先查看注解的源码:

注解使用必须在xml中开启注解任务，使注解生效:

 

 

 

测试类:(每十秒钟打印一次日志)

package cn.xm.exam.job;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.scheduling.annotation.Scheduled;import org.springframework.stereotype.Component;@Componentpublic class FirstAnnotationJob {    private static final Logger log = LoggerFactory.getLogger(FirstAnnotationJob.class);    private static int count;    @Scheduled(cron = "0/10 * * * * ?")    public void cron() {        log.info("spring anno task execute times {}", count++);    }}

 

结果:

2018-11-14 22:44:40 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 02018-11-14 22:44:50 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 12018-11-14 22:45:00 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 22018-11-14 22:45:10 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 3

 

 

查看@Scheduled的源码:(位于spring-context包内)

/** Eclipse Class Decompiler plugin, Copyright (c) 2017 Chen Chao. */package org.springframework.scheduling.annotation;import java.lang.annotation.Documented;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE})@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface Scheduled {    /**     * A cron-like expression, extending the usual UN*X definition to include     * triggers on the second as well as minute, hour, day of month, month     * and day of week.  e.g. {
    @code "0 * * * * MON-FRI"} means once per minute on     * weekdays (at the top of the minute - the 0th second).     * @return an expression that can be parsed to a cron schedule     * @see org.springframework.scheduling.support.CronSequenceGenerator     */    String cron() default "";    /**     * Execute the annotated method with a fixed period between the end     * of the last invocation and the start of the next.     * @return the delay in milliseconds     */    long fixedDelay() default -1;    /**     * Execute the annotated method with a fixed period between invocations.     * @return the period in milliseconds     */    long fixedRate() default -1;    /**     * Number of milliseconds to delay before the first execution of a     * {
    @link #fixedRate()} or {
    @link #fixedDelay()} task.     * @return the initial delay in milliseconds     * @since 3.2     */    long initialDelay() default 0;}

 

参数解释:(其实源码的注释也写的非常清楚了)

cron:cron表达式

fixedDelay:表示从上一个任务完成开始到下一个任务开始的间隔，单位是毫秒

fixedRate:从上一个任务开始到下一个任务开始的间隔，单位是毫秒。

initialDelay:任务第一次被调用前的延时，单位毫秒。

需要注意的是上面的前三个属性只能保留一个，不能同时出现，最后一个延时操作可以与上面三个参数搭配。否则会报异常如下:

java.lang.IllegalArgumentException: Exactly one of the 'cron', 'fixedDelay', or 'fixedRate' attributes is required.

 

 

接下来我们测试上面的参数: 

fixedDelay :方法中模拟处理用了2s

package cn.xm.exam.job;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.scheduling.annotation.Scheduled;import org.springframework.stereotype.Component;@Componentpublic class FirstAnnotationJob {    private static final Logger log = LoggerFactory.getLogger(FirstAnnotationJob.class);    private static int count;    @Scheduled(fixedDelay = 10000)    public void cron() {        try {            Thread.sleep(2000);        } catch (InterruptedException e) {            log.error("InterruptedException ", e);        }        log.info("spring anno task execute times {}", count++);    }}

 

 

结果:(实际每两次任务中间相差12s，也就是第一次任务结束10s后开启下次任务)

2018-11-14 23:02:04 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 12018-11-14 23:02:16 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 22018-11-14 23:02:28 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 32018-11-14 23:02:40 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 4

 

 

 

fixedRate测试:

package cn.xm.exam.job;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.scheduling.annotation.Scheduled;import org.springframework.stereotype.Component;@Componentpublic class FirstAnnotationJob {    private static final Logger log = LoggerFactory.getLogger(FirstAnnotationJob.class);    private static int count;    @Scheduled(fixedRate = 10000)    public void cron() {        try {            Thread.sleep(2000);        } catch (InterruptedException e) {            log.error("InterruptedException ", e);        }        log.info("spring anno task execute times {}", count++);    }}

 

结果:(每两次任务相差10s，也就是本次任务开始之后10s后就开启下次任务，不管中间处理花费多长时间)

2018-11-14 23:04:47 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 12018-11-14 23:04:57 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 22018-11-14 23:05:07 [cn.xm.exam.job.FirstAnnotationJob]-[INFO] spring anno task execute times 3

 

 

 

至此完成了springtask的测试，确实比quartz简便的多，使用也简单。

附一个在线cron表达式生成器: