SpringBoot动态定时功能实现方案详解

在SpringBoot项目中简单使用定时任务，不过由于要借助cron表达式且都提前定义好放在配置文件里，不能在项目运行中动态修改任务执行时间，实在不太灵活。现在我们就来实现可以动态修改cron表达式的定时任务,感兴趣的可以了解一下

业务场景

基于上篇程序，做了一版动态定时程序，然后发现这个定时程序需要在下次执行的时候会加载新的时间，所以如果改了定时程序不能马上触发，所以想到一种方法，在保存定时程序的时候将cron表达式传过去，然后触发定时程序，下面看看怎么实现

环境准备

开发环境

JDK 1.8
SpringBoot2.2.1
Maven 3.2+

开发工具

IntelliJ IDEA
smartGit
Navicat15

实现方案

基于上一版进行改进：

先根据选择的星期生成cron表达式，保存到数据库里，同时更改cron表达式手动触发定时程序加载最新的cron表达式
根据保存的cron表达式规则执行定时程序
通过CommandLineRunner设置启动加载
加上线程池，提高线程复用率和程序性能

加上ThreadPoolTaskScheduler，支持同步和异步两种方式：

import lombok.extern.slf4j.Slf4j;
import org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.AsyncConfigurer;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.SchedulingConfigurer;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
import org.springframework.scheduling.config.ScheduledTaskRegistrar;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
@Configuration
@Slf4j
public class ScheduleConfig implements SchedulingConfigurer , AsyncConfigurer {
    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        taskRegistrar.setScheduler(taskScheduler());
    }
    @Bean(destroyMethod="shutdown" , name = "taskScheduler")
    public ThreadPoolTaskScheduler taskScheduler() {
        ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
        scheduler.setPoolSize(10);
        scheduler.setThreadNamePrefix("itemTask-");
        scheduler.setAwaitTerminationSeconds(600);
        scheduler.setWaitForTasksToCompleteOnShutdown(true);
        return scheduler;
    }
    @Bean(name = "asyncExecutor")
    public ThreadPoolTaskExecutor asyncExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(10);
        executor.setQueueCapacity(1000);
        executor.setKeepAliveSeconds(600);
        executor.setMaxPoolSize(20);
        executor.setThreadNamePrefix("itemAsyncTask-");
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        executor.initialize();
        return executor;
    }
    @Override
    public Executor getAsyncExecutor() {
        return asyncExecutor();
    }
    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return (throwable, method, objects) -> {
            log.error("异步任务异常,message {} , method {} , params" , throwable , method , objects);
        };
    }
}

加上一个SchedulerTaskJob接口：

public interface SchedulerTaskJob{
    void executeTask();
}

AbstractScheduler 抽象类，提供基本的功能

import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.Trigger;
import org.springframework.scheduling.TriggerContext;
import org.springframework.scheduling.annotation.SchedulingConfigurer;
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
import org.springframework.scheduling.config.ScheduledTaskRegistrar;
import org.springframework.scheduling.support.CronTrigger;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
import java.util.Date;
@Slf4j
@Component
@Data
public abstract class AbstractScheduler implements SchedulerTaskJob{
    @Resource(name = "taskScheduler")
    private ThreadPoolTaskScheduler threadPoolTaskScheduler;
    @Override
    public void executeTask() {
        String cron = getCronString();
        Runnable task = () -> {
            // 执行业务
            doBusiness();
        };
        Trigger trigger = new Trigger()   {
            @Override
            public Date nextExecutionTime(TriggerContext triggerContext) {
                CronTrigger trigger;
                try {
                    trigger = new CronTrigger(cron);
                    return trigger.nextExecutionTime(triggerContext);
                } catch (Exception e) {
                    log.error("cron表达式异常，已经启用默认配置");
                    // 配置cron表达式异常，执行默认的表达式
                    trigger = new CronTrigger(getDefaultCron());
                    return trigger.nextExecutionTime(triggerContext);
                }
            }
        };
        threadPoolTaskScheduler.schedule(task , trigger);
    }
    protected abstract String getCronString();
    protected abstract void doBusiness();
    protected abstract String getDefaultCron();
}

实现类，基于自己的业务实现，然后事项抽象类，通过模板模式进行编程

import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.toolkit.Wrappers;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.time.LocalDateTime;
@Service
@Slf4j
@Data
public class ItemSyncScheduler extends AbstractScheduler {
    @Value("${configtask.default.itemsync}")
    private String defaultCron ;
    private String cronString ;
    @Override
    protected String getCronString() {
        if (StrUtil.isNotBlank(cronString))  return cronString;
        SyncConfigModel configModel = syncConfigService.getOne(Wrappers.<SyncConfigModel>lambdaQuery()
                .eq(SyncConfigModel::getBizType, 1)
                .last("limit 1"));
        if (configModel == null) return defaultCron;
        return configModel.getCronStr();
    }
    @Override
    protected void doBusiness() {
        log.info("执行业务...");
        log.info("执行时间:{}"  , LocalDateTime.now());
       // 执行业务
    }
    @Override
    protected String getDefaultCron() {
        return defaultCron;
    }
}

如果更改了cron表达式，程序不会马上触发，所以直接开放一个接口出来，调用的时候，设置最新的表达式，然后重新调用定时程序

import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
@Slf4j
public class ItemSchedulerController {
    private ItemSyncScheduler itemSyncScheduler;
    @Autowired
    public ItemSchedulerController(ItemSyncScheduler itemSyncScheduler) {
        this.itemSyncScheduler= itemSyncScheduler;
    }
    @GetMapping(value = "/updateItemCron")
    @ApiOperation(value = "更新cron表达式")
    public void updateItemCron(@RequestParam("cronString") String cronString) {
        log.info("更新cron表达式...");
        log.info("cronString:{}" , cronString);
        itemSyncScheduler.setCronString(cronString);
        itemSyncScheduler.executeTask();
    }
}

实现CommandLineRunner ，实现Springboot启动加载

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
@Component
@Order(1)
public class SchedulerTaskRunner implements CommandLineRunner {
    private ItemSyncScheduler itemSyncScheduler;
    @Autowired
    public SchedulerTaskRunner(ItemSyncScheduler itemSyncScheduler) {
        this.itemSyncScheduler= itemSyncScheduler;
    }
    @Override
    public void run(String... args) throws Exception {
        itemSyncScheduler.executeTask();
    }
}

归纳总结

基于上一版定时程序的问题，做了改进，加上了线程池和做到了动态触发，网上的资料很多都是直接写明使用SchedulingConfigurer来实现动态定时程序，不过很多都写明场景，本文通过实际，写明实现方法，本文是在保存定时程序的时候，设置最新的cron表达式，调一下接口重新加载，还可以使用canal等中间件监听数据表，如果改了就再设置cron表达式，然后触发程序

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