原文网址：Spring定时任务--手动执行定时任务（替代@Scheduled）
简介
本文介绍SpringBoot如何手动执行定时任务。
之前此文已经介绍过，直接用@Scheduled即可使用Spring的定时任务，但有时需要手动去提交定时任务，比如：
- 从其他位置获取cron配置，无法写到注解。
- 有不确定个数的任务，不能在代码中写死。
方案1：实现 SchedulingConfigurer 接口
本处从数据库读取配置，然后提交定时任务。
创建定时器
编写定时任务，这里添加的是TriggerTask，循环读取我们在数据库设置好的执行周期，以及执行相关定时任务的内容。
@Configuration
@EnableScheduling
public class DynamicScheduleTask implements SchedulingConfigurer {
@Autowired
private 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("执行动态定时任务: " + 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);
}
);
}
}表结构与数据
开启本地数据库mysql，随便打开查询窗口，然后执行脚本内容，如下
DROP DATABASE IF EXISTS `socks`;
CREATE DATABASE `socks`;
USE `SOCKS`;
DROP TABLE IF EXISTS `cron`;
CREATE TABLE `cron` (
`cron_id` varchar(30) NOT NULL PRIMARY KEY,
`cron` varchar(30) NOT NULL
);
INSERT INTO `cron` VALUES ('1', '0/5 * * * * ?');
项目中的application.yml 添加数据源
spring:
datasource:
url: jdbc:mysql://localhost:3306/socks
username: root
password: 123456启动测试
启动应用后，查看控制台，打印时间是我们预期的每10秒一次：
打开Navicat ，将执行周期修改为每6秒执行一次，如图
如果在数据库修改时格式出现错误，则定时任务会停止，即使重新修改正确；此时只能重新启动项目才能恢复。
方案2：ThreadPoolTaskScheduler
上边的实例的定时任务在SprinBoot在启动时就启动，也可以在代码中任意启动/关闭/调整时间。如下：
package com.example.demo.task;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
import org.springframework.scheduling.support.CronTrigger;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.Date;
import java.util.concurrent.ScheduledFuture;
@RestController
@Component
public class TestScheduler {
@Autowired
private ThreadPoolTaskScheduler threadPoolTaskScheduler;
private ScheduledFuture<?> future;
@Bean
public ThreadPoolTaskScheduler threadPoolTaskScheduler() {
return new ThreadPoolTaskScheduler();
}
@RequestMapping("/startCron")
public String startCron() {
future = threadPoolTaskScheduler.schedule(new MyRunnable(), new CronTrigger("0/5 * * * * *"));
System.out.println("DynamicTask.startCron()");
return "startCron";
}
@RequestMapping("/stopCron")
public String stopCron() {
if (future != null) {
future.cancel(true);
}
System.out.println("DynamicTask.stopCron()");
return "stopCron";
}
@RequestMapping("/changeCron10")
public String startCron10() {
stopCron();// 先停止，在开启.
future = threadPoolTaskScheduler.schedule(new MyRunnable(), new CronTrigger("*/10 * * * * *"));
System.out.println("DynamicTask.startCron10()");
return "changeCron10";
}
private class MyRunnable implements Runnable {
@Override
public void run() {
System.out.println("DynamicTask.MyRunnable.run()，" + new Date());
}
}
}
浏览器分别输入：http://localhost:8080/startCron、http://localhost:8080/stopCron
执行结果
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.3.0.RELEASE)
2020-05-27 19:48:02.370 INFO 6804 --- [ main] com.example.demo.DemoApplication : Starting DemoApplication on liu-PC with PID 6804 (E:\work\idea_proj\test-SpringBoot\target\classes started by liu in E:\work\idea_proj\test-SpringBoot)
2020-05-27 19:48:02.373 INFO 6804 --- [ main] com.example.demo.DemoApplication : No active profile set, falling back to default profiles: default
2020-05-27 19:48:03.675 INFO 6804 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2020-05-27 19:48:03.684 INFO 6804 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2020-05-27 19:48:03.684 INFO 6804 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.35]
2020-05-27 19:48:03.941 INFO 6804 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2020-05-27 19:48:03.941 INFO 6804 --- [ main] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1523 ms
2020-05-27 19:48:04.001 INFO 6804 --- [ main] o.s.s.c.ThreadPoolTaskScheduler : Initializing ExecutorService 'threadPoolTaskScheduler'
2020-05-27 19:48:04.405 INFO 6804 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2020-05-27 19:48:04.419 INFO 6804 --- [ main] com.example.demo.DemoApplication : Started DemoApplication in 3.328 seconds (JVM running for 8.111)
2020-05-27 19:48:39.380 INFO 6804 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet'
2020-05-27 19:48:39.380 INFO 6804 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2020-05-27 19:48:39.405 INFO 6804 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Completed initialization in 25 ms
DynamicTask.startCron()
DynamicTask.MyRunnable.run()，Wed May 27 19:48:50 CST 2020
DynamicTask.MyRunnable.run()，Wed May 27 19:48:55 CST 2020
DynamicTask.MyRunnable.run()，Wed May 27 19:49:00 CST 2020
DynamicTask.MyRunnable.run()，Wed May 27 19:49:05 CST 2020
DynamicTask.MyRunnable.run()，Wed May 27 19:49:10 CST 2020
DynamicTask.stopCron()
