详解SpringBoot 创建定时任务（配合数据库动态执行）

@Configuration //1.主要用于标记配置类，兼备Component的效果。
@EnableScheduling // 2.开启定时任务
public class SimpleScheduleConfig {
  //3.添加定时任务
  @Scheduled(cron = "0/5 * * * * ?")
  private void configureTasks() {
    System.err.println("执行定时任务1: " + LocalDateTime.now());
  }
}

  <!--依赖管理 -->
  <dependencies>
    <dependency><!--添加Web依赖 -->
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency><!--添加Mybatis依赖 -->
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-starter</artifactId>
      <version>1.3.1</version>
    </dependency>
    <dependency><!--添加MySql依赖 -->
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency><!--添加Test依赖 -->
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
  </dependencies>

DROP DATABASE IF EXISTS `socks`;
CREATE DATABASE `socks`;
USE `SOCKS`;
DROP TABLE IF EXISTS `cron`;
CREATE TABLE `cron` (
 `cron_id` varchar(30),
 `cron` varchar(30) 
);
INSERT INTO `cron` VALUES ('1', '0/5 * * * * ?');

spring:
 datasource:
  url: jdbc:mysql://localhost:3306/socks?useSSL=false
  username: root
  password: root

@Configuration
@EnableScheduling
public class CompleteScheduleConfig implements SchedulingConfigurer {

  @Mapper
  public interface CronMapper {
    @Select("select cron from cron limit 1")
    String getCron();
  }

  @Autowired
  @SuppressWarnings("all")
  CronMapper cronMapper;

  /**
   * 执行定时任务.
   */
  @Override
  public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
    taskRegistrar.addTriggerTask(
        //1.添加任务内容(Runnable)
        () -> System.out.println("执行定时任务2: " + LocalDateTime.now().toLocalTime()),
        //2.设置执行周期(Trigger)
        triggerContext -> {
          //2.1 从数据库获取执行周期
          String cron = cronMapper.getCron();
          //2.2 合法性校验.
          if (StringUtils.isEmpty(cron)) {
            // Omitted Code ..
          }
          //2.3 返回执行周期(Date)
          return new CronTrigger(cron).nextExecutionTime(triggerContext);
        }
    );
  }

}