SpringBoot最簡(jiǎn)單的定時(shí)任務(wù)@Scheduler的使用及解讀

更新時(shí)間：2025年03月22日 10:50:14 作者：七年·

這篇文章主要介紹了SpringBoot最簡(jiǎn)單的定時(shí)任務(wù)@Scheduler的使用及解讀,具有很好的參考價(jià)值,希望對(duì)大家有所幫助,如有錯(cuò)誤或未考慮完全的地方,望不吝賜教

SpringBoot定時(shí)任務(wù)@Scheduler

Spring Boot 中一般來(lái)說(shuō)定時(shí)任務(wù)使用@Scheduler注解或者Quartz框架，或者自定義線程實(shí)現(xiàn),最簡(jiǎn)單的當(dāng)屬@Scheduler注解

依賴：

       <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.1.3.RELEASE</version>
        </dependency>

創(chuàng)建Application：

@SpringBootApplication
//此注解開(kāi)啟異步定時(shí)任務(wù),必須要有
@EnableScheduling
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

創(chuàng)建任務(wù)：

@Component
public class SpringJob {
    //springboot掃描到這個(gè)注解就會(huì)按照定義的計(jì)劃去執(zhí)行任務(wù)
    //cron是cron表達(dá)式,因?yàn)楹芎?jiǎn)單但是描述要話費(fèi)比較多的篇幅,所以略
    @Scheduled(cron = "0/1 * * * * ?")
    public void myJob(){
        //任務(wù)處理邏輯
        System.out.println(new Date() +"Spring Scheduler 執(zhí)行");
    }
}

啟動(dòng) Application：

上述是一個(gè)最簡(jiǎn)單的單job cron調(diào)度的實(shí)現(xiàn).

@Scheduler中的參數(shù)：

String cron() default ""; 
String zone() default "";
long fixedDelay() default -1;
String fixedDelayString() default "";
long fixedRate() default -1;
String fixedRateString() default "";
long initialDelay() default -1;
String initialDelayString() default "";

String cron() default “”;接收一個(gè)cron表達(dá)式字符串,以cron表達(dá)式調(diào)度任務(wù)
String zone() default “”;設(shè)置時(shí)區(qū),不設(shè)置的話cron就基于服務(wù)器所在的本地時(shí)區(qū)
long fixedDelay() default -1;設(shè)置任務(wù)間隔時(shí)間(毫秒),就是任務(wù)結(jié)束后再過(guò)多久開(kāi)始新的任務(wù)
String fixedDelayString() default “”;同 long fixedDelay(),只是把參數(shù)從long改成string
long fixedRate() default -1;設(shè)置任務(wù)每隔多久開(kāi)啟
String fixedRateString() default “”;同 long fixedRate() 只是把參數(shù)從long改成string
long initialDelay() default -1;第一次執(zhí)行延遲時(shí)間(啟動(dòng)后多久才開(kāi)始任務(wù))
String initialDelayString() default “”;同 long initialDelay()

spring boot 默認(rèn)開(kāi)啟一個(gè)線程執(zhí)行任務(wù)：

@Component
public class SpringJob {

    @Scheduled(fixedRateString = "1000")
    public void myJob2() throws InterruptedException {
        System.out.println(new Date() +" job開(kāi)啟");
        Thread.sleep(2000);
        System.out.println(new Date() +" job結(jié)束");
    }
}

執(zhí)行結(jié)果:
Fri Jul 31 10:34:16 CST 2020 job開(kāi)啟
Fri Jul 31 10:34:18 CST 2020 job結(jié)束
Fri Jul 31 10:34:18 CST 2020 job開(kāi)啟
Fri Jul 31 10:34:20 CST 2020 job結(jié)束
Fri Jul 31 10:34:20 CST 2020 job開(kāi)啟
Fri Jul 31 10:34:22 CST 2020 job結(jié)束
Fri Jul 31 10:34:22 CST 2020 job開(kāi)啟
Fri Jul 31 10:34:24 CST 2020 job結(jié)束
Fri Jul 31 10:34:24 CST 2020 job開(kāi)啟
Fri Jul 31 10:34:26 CST 2020 job結(jié)束
Fri Jul 31 10:34:26 CST 2020 job開(kāi)啟
Fri Jul 31 10:34:28 CST 2020 job結(jié)束
Fri Jul 31 10:34:28 CST 2020 job開(kāi)啟
Fri Jul 31 10:34:30 CST 2020 job結(jié)束

設(shè)置的任務(wù)為每隔1秒中開(kāi)啟一次，一次任務(wù)執(zhí)行時(shí)間是2秒，但是發(fā)現(xiàn)執(zhí)行的過(guò)程是，同一時(shí)間只有一個(gè)線程在執(zhí)行.也就是單線程執(zhí)行

現(xiàn)在執(zhí)行兩個(gè)job，單線程情況下，自然也是無(wú)法并發(fā)的：

@Component
public class SpringJob {
    @Scheduled(fixedRateString  = "2000")
    public void myJob() throws InterruptedException {
        System.out.println(new Date() +" job1開(kāi)始");
        Thread.sleep(10000);
        System.out.println(new Date() +" job1結(jié)束");
    }
    @Scheduled(fixedRateString = "1000")
    public void myJob2() throws InterruptedException {
        System.out.println(new Date() +" job2開(kāi)啟");
        Thread.sleep(2000);
        System.out.println(new Date() +" job2結(jié)束");
    }
}
執(zhí)行結(jié)果:
Fri Jul 31 10:51:56 CST 2020 job1開(kāi)始
Fri Jul 31 10:52:06 CST 2020 job1結(jié)束
Fri Jul 31 10:52:06 CST 2020 job2開(kāi)啟
Fri Jul 31 10:52:08 CST 2020 job2結(jié)束
Fri Jul 31 10:52:08 CST 2020 job2開(kāi)啟
Fri Jul 31 10:52:10 CST 2020 job2結(jié)束
Fri Jul 31 10:52:10 CST 2020 job1開(kāi)始
Fri Jul 31 10:52:20 CST 2020 job1結(jié)束
Fri Jul 31 10:52:20 CST 2020 job2開(kāi)啟
Fri Jul 31 10:52:22 CST 2020 job2結(jié)束
Fri Jul 31 10:52:22 CST 2020 job2開(kāi)啟
Fri Jul 31 10:52:24 CST 2020 job2結(jié)束

任務(wù)的每次執(zhí)行，無(wú)論是單個(gè)任務(wù)多次執(zhí)行，還是多個(gè)任務(wù)一次執(zhí)行，對(duì)于線程來(lái)說(shuō)都是一樣的，都需要開(kāi)啟一個(gè)線程.有幾個(gè)線程就可以幾個(gè)任務(wù)(或者相同任務(wù)的多次)并發(fā)執(zhí)行

默認(rèn)情況下，scheduler只有一個(gè)線程

自定義線程池，添加一個(gè)配置類(lèi)：

@Configuration
public class ScheduleConfig implements SchedulingConfigurer {
    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        taskRegistrar.setScheduler(setExecutor());
    }
    @Bean
    public Executor setExecutor() {
        //設(shè)置線程個(gè)數(shù),這里我們?cè)O(shè)置5個(gè)(同一時(shí)間可以并行執(zhí)行5個(gè)線程)
        return Executors.newScheduledThreadPool(5);
    }
}

此時(shí)執(zhí)行上方的單個(gè)任務(wù)：

Fri Jul 31 10:55:18 CST 2020 job開(kāi)啟
Fri Jul 31 10:55:20 CST 2020 job結(jié)束
Fri Jul 31 10:55:20 CST 2020 job開(kāi)啟
Fri Jul 31 10:55:22 CST 2020 job結(jié)束
Fri Jul 31 10:55:22 CST 2020 job開(kāi)啟
Fri Jul 31 10:55:24 CST 2020 job結(jié)束
Fri Jul 31 10:55:24 CST 2020 job開(kāi)啟
Fri Jul 31 10:55:26 CST 2020 job結(jié)束

單個(gè)任務(wù)還是只能串行執(zhí)行.

執(zhí)行上方的兩個(gè)任務(wù)：

Fri Jul 31 10:59:59 CST 2020 job2開(kāi)啟
Fri Jul 31 10:59:59 CST 2020 job1開(kāi)始
Fri Jul 31 11:00:01 CST 2020 job2結(jié)束
Fri Jul 31 11:00:01 CST 2020 job2開(kāi)啟
Fri Jul 31 11:00:03 CST 2020 job2結(jié)束
Fri Jul 31 11:00:03 CST 2020 job2開(kāi)啟
Fri Jul 31 11:00:05 CST 2020 job2結(jié)束
Fri Jul 31 11:00:05 CST 2020 job2開(kāi)啟
Fri Jul 31 11:00:07 CST 2020 job2結(jié)束
Fri Jul 31 11:00:07 CST 2020 job2開(kāi)啟
Fri Jul 31 11:00:09 CST 2020 job1結(jié)束
Fri Jul 31 11:00:09 CST 2020 job1開(kāi)始
Fri Jul 31 11:00:09 CST 2020 job2結(jié)束

發(fā)現(xiàn)任務(wù)跟job1與job2之間是可以并發(fā)執(zhí)行的.但是對(duì)于job1的多次任務(wù)，job2的多次任務(wù)，都是串行執(zhí)行的.

現(xiàn)在線程池中有多個(gè)線程，job與job之間可以并發(fā)，如何讓單個(gè)job的多次可以并發(fā)執(zhí)行，就需要@Async注解，此注解要用在job的方法上.@EnableAsync注解，此注解要在Application類(lèi)上，此時(shí)，job的多次執(zhí)行也可以并發(fā)執(zhí)行了.

@SpringBootApplication
@EnableScheduling
@EnableAsync
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

@Component
public class SpringJob {
    @Async   
    @Scheduled(fixedRateString = "2000")
    public void myJob() throws InterruptedException {
        System.out.println(new Date() + " job1開(kāi)始");
        Thread.sleep(10000);
        System.out.println(new Date() + " job1結(jié)束");
    }
    
    @Scheduled(fixedRateString = "1000")
    public void myJob2() throws InterruptedException {
        System.out.println(new Date() + " job2開(kāi)啟");
        Thread.sleep(2000);
        System.out.println(new Date() + " job2結(jié)束");
    }
}
執(zhí)行結(jié)果:
Fri Jul 31 11:08:57 CST 2020 job2開(kāi)啟
Fri Jul 31 11:08:57 CST 2020 job1開(kāi)始
Fri Jul 31 11:08:59 CST 2020 job1開(kāi)始
Fri Jul 31 11:08:59 CST 2020 job2結(jié)束
Fri Jul 31 11:08:59 CST 2020 job2開(kāi)啟
Fri Jul 31 11:09:01 CST 2020 job1開(kāi)始
Fri Jul 31 11:09:01 CST 2020 job2結(jié)束
Fri Jul 31 11:09:01 CST 2020 job2開(kāi)啟
Fri Jul 31 11:09:03 CST 2020 job1開(kāi)始
Fri Jul 31 11:09:03 CST 2020 job2結(jié)束
Fri Jul 31 11:09:03 CST 2020 job2開(kāi)啟

可以發(fā)現(xiàn)job1在前一次沒(méi)有執(zhí)行完時(shí)，就已經(jīng)開(kāi)始執(zhí)行了.

重要一點(diǎn)

自定線程池Configuration是為了啟用多線程，此時(shí)可以起到j(luò)ob1與job2之間的并發(fā)執(zhí)行，但是job1多次任務(wù)只能串行執(zhí)行，所以才增加了@Aysnc跟@EnableAsync注解.

@EnableAsync注解有兩個(gè)作用，1單線程變多線程，2 可以允許單個(gè)job多次運(yùn)行時(shí)并行執(zhí)行(需要再加@Async)，如果已經(jīng)是多線程了，但是不加此注解，同一個(gè)job的多次執(zhí)行還是串行.

其實(shí)在使用@EnableAsync注解的時(shí)候，springboot會(huì)把自定義的configuration給覆蓋掉，即使在configuration中配置了單個(gè)線程，任務(wù)的并發(fā)也不會(huì)受到影響.所以推薦使用@EnableAsync來(lái)完成多線程配置再加@Aysnc來(lái)完成任務(wù)的并發(fā).