springboot定时任务

springboot 自带定时任务 EnableScheduling
官方文档链接 https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#boot-features-task-execution-scheduling

1.在启动类 Application 加上 @EnableScheduling 注解

他来自 org.springframework.scheduling.annotation; 包 3.1版本出现

@SpringBootApplication
//定时开启
@EnableScheduling
public class DemoApplication {
	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}
}

2.在调度方法上面加上Scheduled注解,记得声明bean

在调度方法上面加上Scheduled注解 来自org.springframework.scheduling.annotation;包 3.0版本出现

//添加 Component 注解
@Component
public class ItemTask {

    //调度的方法5秒执行一次
    @Scheduled(fixedDelay = 5 * 1000)
    public void itemTack() {
        System.out.println("=================");
    }
    
    //调度方法十秒执行一次
    @Scheduled(cron = "0/10 * * * * ? ")
    public void itemTack2() {
        System.out.println("=================");
    }
}

Scheduling注解支持很多种表达式,点开源码可以看到

分别是 cron ,zone ,fixedDelay,fixedDelayString,fixedRate,fixedRateString
,initialDelay,initialDelayString
相应的源码注释,作者也复制出来了,想要深入的读者自行翻译,或者点击源代码阅读,并且使用

/**
	 * A special cron expression value that indicates a disabled trigger: {@value}.
	 * 
This is primarily meant for use with ${...} placeholders, allowing for
	 * external disabling of corresponding scheduled methods.
	 * @since 5.1
	 */
	String CRON_DISABLED = "-";


	/**
	 * 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).
	 * 
The special value {@link #CRON_DISABLED "-"} indicates a disabled cron trigger,
	 * primarily meant for externally specified values resolved by a ${...} placeholder.
	 * @return an expression that can be parsed to a cron schedule
	 * @see org.springframework.scheduling.support.CronSequenceGenerator
	 */
	String cron() default "";

	/**
	 * A time zone for which the cron expression will be resolved. By default, this
	 * attribute is the empty String (i.e. the server's local time zone will be used).
	 * @return a zone id accepted by {@link java.util.TimeZone#getTimeZone(String)},
	 * or an empty String to indicate the server's default time zone
	 * @since 4.0
	 * @see org.springframework.scheduling.support.CronTrigger#CronTrigger(String, java.util.TimeZone)
	 * @see java.util.TimeZone
	 */
	String zone() default "";

	/**
	 * Execute the annotated method with a fixed period in milliseconds 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 in milliseconds between the
	 * end of the last invocation and the start of the next.
	 * @return the delay in milliseconds as a String value, e.g. a placeholder
	 * or a {@link java.time.Duration#parse java.time.Duration} compliant value
	 * @since 3.2.2
	 */
	String fixedDelayString() default "";

	/**
	 * Execute the annotated method with a fixed period in milliseconds between
	 * invocations.
	 * @return the period in milliseconds
	 */
	long fixedRate() default -1;

	/**
	 * Execute the annotated method with a fixed period in milliseconds between
	 * invocations.
	 * @return the period in milliseconds as a String value, e.g. a placeholder
	 * or a {@link java.time.Duration#parse java.time.Duration} compliant value
	 * @since 3.2.2
	 */
	String fixedRateString() default "";

	/**
	 * 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 -1;

	/**
	 * Number of milliseconds to delay before the first execution of a
	 * {@link #fixedRate()} or {@link #fixedDelay()} task.
	 * @return the initial delay in milliseconds as a String value, e.g. a placeholder
	 * or a {@link java.time.Duration#parse java.time.Duration} compliant value
	 * @since 3.2.2
	 */
	String initialDelayString() default "";