SpringBoot @Scheduled 定时任务 入门demo

项目结果：

1、     项目所需的jar包，因为是SpringBoot的demo,所以这里只需要引入spring-boot-starter-parent和spring-boot-starter-web即可。

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.springboot</groupId><artifactId>scheduled-demo</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>scheduled-demo</name><description>Demo project for Spring Boot</description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.0.6.RELEASE</version><relativePath/> <!-- lookup parent from repository --></parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

1、启动类：加上@EnableScheduling，这样才会去扫描@Scheduled的方法，去掉之后@Scheduled的方法将不会被执行。

package com.springboot.scheduleddemo;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;@SpringBootApplication
@EnableScheduling
public class ScheduledDemoApplication {public static void main(String[] args) {SpringApplication.run(ScheduledDemoApplication.class, args);}
}

2、写定时任务：

参考：在线Cron表达式

@Scheduled() 注解中写入Cron表达式。

此处将类加上@Component注解或者@Service均可。

"0/1 * * * * ? "表示每秒执行一次

package com.springboot.scheduleddemo.service;import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;import java.util.Date;/*** @author: Lucifer* @create: 2018-10-29 22:39* @description:**/
@Component
public class ScheduledService {@Scheduled(cron = "0/1 * * * * ? ")public void sayHello(){System.out.println("定时任务1："+new Date());}}

控制台：

3、加入SayNo方法

@Scheduled(cron = "0/1 * * * * ? ")public void sayNo(){System.out.println("定时任务2"+new Date()+".......No");}

此时启动，会看到控制台如下图：此时是同步的，串行，先执行sayHello，再执行SayNo.

4、加上@Async

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

再次查看控制台：如图

此时不再是按顺序去执行了，而是异步。在启动类加上@Async，表示执行的是异步的