spring-boot之简单定时任务

Posted 2020-07-09

首先是pom.xml依赖：

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.springboot.samples</groupId>
    <artifactId>SpringBoot_Cron</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>SpringBoot_Cron Maven Webapp</name>
    <url>http://maven.apache.org</url>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.5.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>

        <!-- http://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
    </dependencies>
    <build>
        <finalName>SpringBoot_Cron</finalName>
    </build>
</project>

然后是定时任务类ScheduledTask：

package hello;

import java.text.SimpleDateFormat;
import java.util.Date;

import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
@Component
public class ScheduledTask {
    
    private static final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    private Integer count0 = 1;
    private Integer count1 = 1;
    private Integer count2 = 1;

    @Scheduled(fixedRate = 5000)        //fixedRate = 5000表示每隔5000ms，Spring scheduling会调用一次该方法，不论该方法的执行时间是多少
    public void reportCurrentTime() throws InterruptedException {
        System.out.println(String.format("---第%s次执行，当前时间为：%s", count0++, dateFormat.format(new Date())));
    }

    @Scheduled(fixedDelay = 10000)        //fixedDelay = 5000表示当方法执行完毕5000ms后，Spring scheduling会再次调用该方法
    public void reportCurrentTimeAfterSleep() throws InterruptedException {
        System.out.println(String.format("===第%s次执行，当前时间为：%s", count1++, dateFormat.format(new Date())));
    }

    @Scheduled(cron = "*/15 * * * * *")        //cron = "*/5 * * * * * *"提供了一种通用的定时任务表达式，这里表示每隔5秒执行一次
    public void reportCurrentTimeCron() throws InterruptedException {
        System.out.println(String.format("+++第%s次执行，当前时间为：%s", count2++, dateFormat.format(new Date())));
    }
    
}

cron表达式的规则：

*/15 * * * * *　　从左至右依次为：分钟（0-59）、小时（1-23）、日期（1-31）、月份（1-12）、星期（0-6,0表示周日）

*/15表示分钟间隔15执行一次即15s执行一次，cron详细介绍猛戳：http://www.manpagez.com/man/5/crontab/

最后是Spring Boot启动类：

package hello;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;

@SpringBootApplication
@EnableScheduling
public class App {

    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
    
}