介绍两种实现方式；配置实现和读取数据库定时任务配置实现。

配置实现比较简单。直接撸代码：

package com;

import java.util.Properties;

import org.apache.ibatis.mapping.DatabaseIdProvider;
import org.apache.ibatis.mapping.VendorDatabaseIdProvider;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ImportResource;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@SpringBootApplicationbr/>@ImportResource("classpath:/config.xml")
@EnableAutoConfiguration
@ComponentScan
@EnableTransactionManagement(proxyTargetClass = true) br/>@MapperScan({"com.*.model.*.mapper","com.*.task"})
@EnableScheduling
public class StartApplication {

public static void main(String[] args) {SpringApplication.run(StartApplication.class, args);
}@Bean
public DatabaseIdProvider getDatabaseIdProvider() {}

}br/>注：在启动类上加注解
@EnableScheduling
@MapperScan 扫描定时任务配置文件的位置。
其他地方无需关注。

定时任务配置类：
package com.*.task;

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

import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;

@Service
public class RunTaskConfig {

private static final SimpleDateFormat format = new SimpleDateFormat("HH:mm:ss");
//初始延迟1秒，每隔2秒
@Scheduled(fixedRateString = "2000",initialDelay = 1000)
public void testFixedRate(){System.out.println("fixedRateString,当前时间：" +format.format(new Date()));
}//每次执行完延迟2秒
@Scheduled(fixedDelayString= "2000")
public void testFixedDelay(){System.out.println("fixedDelayString,当前时间：" +format.format(new Date()));
}
//每隔3秒执行一次
@Scheduled(cron="0/3 * * * * ?")
public void testCron(){System.out.println("cron,当前时间：" +format.format(new Date()));
}

}

配置完成，项目启动后配置的定时任务会自动执行。

Springboot 定时任务 的数据库实现方式：
数据表实体
id ， 执行类， 执行方法， 是否生效， 时间表达式；

SpringBoot 定时任务实现原理：启动Spring 会扫描@Scheduled 注解，读取注解配置信息。
获取定时任务，解析，注册成可执行的定时任务。

数据库活动定时任务实现具体代码如下
package com.tansun.task;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TimeZone;
import java.util.concurrent.ScheduledExecutorService;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.aop.support.AopUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.NoUniqueBeanDefinitionException;
import org.springframework.beans.factory.config.AutowireCapableBeanFactory;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.config.NamedBeanHolder;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.scheduling.TaskScheduler;
import org.springframework.scheduling.annotation.SchedulingConfigurer;
import org.springframework.scheduling.config.CronTask;
import org.springframework.scheduling.config.ScheduledTask;
import org.springframework.scheduling.config.ScheduledTaskRegistrar;
import org.springframework.scheduling.support.CronTrigger;
import org.springframework.scheduling.support.ScheduledMethodRunnable;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import com.tansun.model.system.dao.RunTaskDao;
import com.tansun.model.system.dao.RunTaskDaoImpl;
import com.tansun.model.system.dao.RunTaskSqlBulider;
import com.tansun.model.system.entity.RunTask;
import com.tansun.web.framework.util.BeanUtil;
/***

• 定时任务启动类，从数据库读取定时任务配置。监控定时任务运行。

• @author kangx
  */
  @Component("BeanDefineConfigue")
  public class EventListen implements ApplicationListener<ContextRefreshedEvent>, ApplicationContextAware{

  public static final String DEFAULT_TASK_SCHEDULER_BEAN_NAME = "taskScheduler";

  protected final Log logger = LogFactory.getLog(getClass());
  // 任务调度对象引用
  private Object scheduler;

  private String beanName;

  private BeanFactory beanFactory;
  // 配置环境上下文信息
  private ApplicationContext applicationContext;
  // 任务调度注册中心，监控定时任务，设置定时任务启动触发器。
  private final ScheduledTaskRegistrar registrar = new ScheduledTaskRegistrar();

  // 定时任务执行体
  private final Map<Object, Set<ScheduledTask>> scheduledTasks =
  new IdentityHashMap<Object, Set<ScheduledTask>>(16);

  public Object getScheduler() {
  return scheduler;
  }

  public void setScheduler(Object scheduler) {
  this.scheduler = scheduler;
  }
  //EmbeddedValueResolver embeddedValueResolver=new EmbeddedValueResolver(null);br/>@Override
  public void onApplicationEvent(ContextRefreshedEvent event) {

  try {RunTaskDao runTaskDao = BeanUtil.getBean(RunTaskDaoImpl.class);RunTaskSqlBulider runTaskSqlBulider = new RunTaskSqlBulider();//查找启动状态的定时任务runTaskSqlBulider.andIsWorkEqualTo("1");int count = runTaskDao.countBySqlBulider(runTaskSqlBulider);List<RunTask> list = new ArrayList<>(); if(count>0){list = runTaskDao.selectListBySqlBulider(runTaskSqlBulider);}for(RunTask runtask:list){//定时任务对象解析，装配及注册processScheduled(runtask);}// 定时任务注册,启动定时任务finishRegistration();            } catch (Exception e) {e.printStackTrace();
  }

  }

  /**

  • 定时任务注册
    */
    private void finishRegistration() {
    if (this.scheduler != null) {
    this.registrar.setScheduler(this.scheduler);
    }
    if (this.beanFactory instanceof ListableBeanFactory) {
    Map<String, SchedulingConfigurer> configurers =
    ((ListableBeanFactory) this.beanFactory).getBeansOfType(SchedulingConfigurer.class);
    for (SchedulingConfigurer configurer : configurers.values()) {
    configurer.configureTasks(this.registrar);
    }
    }
    if (this.registrar.hasTasks() && this.registrar.getScheduler() == null) {
    try {
    this.registrar.setTaskScheduler(resolveSchedulerBean(TaskScheduler.class, false));
    }
    catch (NoUniqueBeanDefinitionException ex) {
    try {
    this.registrar.setTaskScheduler(resolveSchedulerBean(TaskScheduler.class, true));
    }
    catch (NoSuchBeanDefinitionException ex2) {
    // 日志记录
    ex2.printStackTrace();
    }
    }
    catch (NoSuchBeanDefinitionException ex) {
    // Search for ScheduledExecutorService bean next...
    try {
    this.registrar.setScheduler(resolveSchedulerBean(ScheduledExecutorService.class, false));
    }
    catch (NoUniqueBeanDefinitionException ex2) {
    try {
    this.registrar.setScheduler(resolveSchedulerBean(ScheduledExecutorService.class, true));
    }
    catch (NoSuchBeanDefinitionException ex3) {
    // 日志记录
    ex3.printStackTrace();
    }
    }
    catch (NoSuchBeanDefinitionException ex2) {
    // 异常日志
    ex2.printStackTrace();
    }
    }
    }
    this.registrar.afterPropertiesSet();
    }
    private <T> T resolveSchedulerBean(Class<T> schedulerType, boolean byName) {
    if (byName) {
    T scheduler = this.beanFactory.getBean(DEFAULT_TASK_SCHEDULER_BEAN_NAME, schedulerType);
    if (this.beanFactory instanceof ConfigurableBeanFactory) {
    ((ConfigurableBeanFactory) this.beanFactory).registerDependentBean(
    DEFAULT_TASK_SCHEDULER_BEAN_NAME, this.beanName);
    }
    return scheduler;
    }
    else if (this.beanFactory instanceof AutowireCapableBeanFactory) {
    NamedBeanHolder<T> holder = ((AutowireCapableBeanFactory) this.beanFactory).resolveNamedBean(schedulerType);
    if (this.beanFactory instanceof ConfigurableBeanFactory) {
    ((ConfigurableBeanFactory) this.beanFactory).registerDependentBean(
    holder.getBeanName(), this.beanName);
    }
    return holder.getBeanInstance();
    }
    else {
    return this.beanFactory.getBean(schedulerType);
    }
    }

  /**

  • 定时任务装配
  • @throws ClassNotFoundException
  • @throws SecurityException

  • @throws NoSuchMethodException
    */
    protected void processScheduled(RunTask runTask) throws Exception{
    try {
    Class clazz = Class.forName(runTask.getExecuteClass());
    Object bean = clazz.newInstance();
    Method method = clazz.getMethod(runTask.getExecuteMethod(), null);
    Method invocableMethod = AopUtils.selectInvocableMethod(method, clazz);
    Runnable runnable = new ScheduledMethodRunnable(bean, invocableMethod);
    boolean processedSchedule = false;

    Set<ScheduledTask> tasks = new LinkedHashSet<ScheduledTask>(4);
    String cron = runTask.getTimeExpression();
    if (StringUtils.hasText(cron)) {processedSchedule = true;String zone = "";TimeZone timeZone;if (StringUtils.hasText(zone)) {timeZone = StringUtils.parseTimeZoneString(zone);}else {timeZone = TimeZone.getDefault();}tasks.add(this.registrar.scheduleCronTask(new CronTask(runnable, new CronTrigger(cron, timeZone))));
    }
    // Finally register the scheduled tasks
    synchronized (this.scheduledTasks) {Set<ScheduledTask> registeredTasks = this.scheduledTasks.get(bean);if (registeredTasks == null) {registeredTasks = new LinkedHashSet<ScheduledTask>(4);this.scheduledTasks.put(bean, registeredTasks);}registeredTasks.addAll(tasks);
    }

    }
    catch (IllegalArgumentException ex) {
    // 日志
    ex.printStackTrace();
    }
    }
    /**

  • 获取环境上下文信息br/>*/
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    this.applicationContext = applicationContext;
    if (this.beanFactory == null) {
    this.beanFactory = applicationContext;
    }
    }
    }