定時任務應用非常廣泛，Java提供的現有解決方案有很多。本次主要講schedule、quartz、xxl-job、shedlock等相關的程式碼實踐。
一、SpringBoot使用Schedule核心程式碼:
@Componentpublic class ScheduleTask { private Logger logger = LoggerFactory.getLogger(ScheduleTask.class); @Scheduled(cron = "0/1 * * * * ? ") public void one() { logger.info("one:" + new Date()); } @Scheduled(cron = "0/1 * * * * ? ") public void two() { logger.info("two:" + new Date()); } @Scheduled(cron = "0/1 * * * * ? ") public void three() { logger.info("three:" + new Date()); }}執行效果如下:
除此之外還可以這樣實現，核心程式碼:
@PropertySource(value = { "classpath:task.properties",}, encoding = "utf-8")@Component("scheduleTask")public class ScheduleTask implements SchedulingConfigurer { @Value("${TEST_JOB_TASK_CRON}") private String cron; @Override public void configureTasks(ScheduledTaskRegistrar scheduledTaskRegistrar) { scheduledTaskRegistrar.addTriggerTask(new Runnable() { @Override public void run() { System.out.println("執行任務:" + DateUtil.date()); } }, new Trigger() { @Override public Date nextExecutionTime(TriggerContext triggerContext) { return new CronTrigger(cron).nextExecutionTime(triggerContext); } }); } public void setCron(String cron) { this.cron = cron; }}有朋友或許很疑惑，為什麼要寫這麼一大堆，這個與前面的程式碼又有何區別呢？
區別是多執行緒並行。其實多執行緒並行也可以不用這麼寫，只需寫一段核心配置類程式碼即可。
定時任務多執行緒配置類:
@Configurationpublic class ScheduleConfig implements SchedulingConfigurer { public void configureTasks(ScheduledTaskRegistrar scheduledTaskRegistrar) { scheduledTaskRegistrar.setScheduler(Executors.newScheduledThreadPool(5)); }}再次啟動，檢視效果，如下:
由此看出走不同的執行緒執行，不同的執行緒執行的好處是，如果某一個執行緒掛掉後，並不會阻塞導致其它定時任務無法執行。
另外如果要想併發執行，前面的配置可以不要，直接用SpringBoot提供的現成註解即可，核心程式碼如下:
@Component@EnableAsyncpublic class ScheduleAsyncTask { private Logger logger = LoggerFactory.getLogger(ScheduleAsyncTask.class); @Scheduled(cron = "0/1 * * * * ? ") @Async public void one() { logger.info("one Async:" + new Date()); } @Scheduled(cron = "0/1 * * * * ? ") @Async public void two() { logger.info("two Async:" + new Date()); } @Scheduled(cron = "0/1 * * * * ? ") @Async public void three() { logger.info("three Async:" + new Date()); }}除此外，還有基於schedule動態定時任務(所謂動態只不過是指cron表示式放在對應的資料表裡)，簡單示例程式碼:
@Configurationpublic class DynamicScheduleTask implements SchedulingConfigurer { @Autowired @SuppressWarnings("all") CronMapper cronMapper; @Mapper public interface CronMapper { @Select("select cron from cron limit 1") public String getCron(); } /** * 執行定時任務. */ public void configureTasks(ScheduledTaskRegistrar taskRegistrar) { taskRegistrar.addTriggerTask( //1.新增任務內容(Runnable) () -> System.out.println("執行動態定時任務: " + LocalDateTime.now().toLocalTime()), //2.設定執行週期(Trigger) triggerContext -> { //2.1 從資料庫獲取執行週期 String cron = cronMapper.getCron(); //2.2 合法性校驗. if (StringUtils.isEmpty(cron)) { // Omitted Code .. } //2.3 返回執行週期(Date) return new CronTrigger(cron).nextExecutionTime(triggerContext); } ); }}核心配置檔案(application.yml):
spring: datasource: url: jdbc:mysql://127.0.0.1:3306/test username: root password: 1234SQL指令碼:
DROP DATABASE IF EXISTS `test`;CREATE DATABASE `test`;USE `test`;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 * * * * ?');執行效果如下:
(2)控制檯不斷輸出定時任務執行日誌
三、SpringBoot使用xxl-job之前寫過一樣的例子，如今簡化了下。關於xxl-job使用詳情，可以參考我的這篇文章:SpringBoot整合Xxl-Job
1.Maven依賴<dependency> <groupId>com.xuxueli</groupId> <artifactId>xxl-job-core</artifactId> <version>2.2.0</version></dependency>@Configurationpublic class XxlJobConfig { private Logger logger = LoggerFactory.getLogger(XxlJobConfig.class); @Value("${xxl.job.admin.addresses}") private String adminAddresses; @Value("${xxl.job.executor.appname}") private String appName; @Value("${xxl.job.executor.ip}") private String ip; @Value("${xxl.job.executor.port}") private int port; @Value("${xxl.job.accessToken}") private String accessToken; @Value("${xxl.job.executor.logpath}") private String logPath; @Value("${xxl.job.executor.logretentiondays}") private int logRetentionDays; @Bean(initMethod = "start", destroyMethod = "destroy") public XxlJobSpringExecutor xxlJobExecutor() { logger.info(">>>>>>>>>>> xxl-job config init."); XxlJobSpringExecutor xxlJobSpringExecutor = new XxlJobSpringExecutor(); xxlJobSpringExecutor.setAdminAddresses(adminAddresses); xxlJobSpringExecutor.setAppname(appName); xxlJobSpringExecutor.setIp(ip); xxlJobSpringExecutor.setPort(port); xxlJobSpringExecutor.setAccessToken(accessToken); xxlJobSpringExecutor.setLogPath(logPath); xxlJobSpringExecutor.setLogRetentionDays(logRetentionDays); return xxlJobSpringExecutor; }}# web portserver.port=8081# no web#spring.main.web-environment=false### xxl-job admin address list, such as "http://address" or "http://address01,http://address02"xxl.job.admin.addresses=http://127.0.0.1:8080/xxl-job-admin### xxl-job, access tokenxxl.job.accessToken=### xxl-job executor appnamexxl.job.executor.appname=blog-job-xxl-job### xxl-job executor registry-address: default use address to registry , otherwise use ip:port if address is nullxxl.job.executor.address=### xxl-job executor server-infoxxl.job.executor.ip=xxl.job.executor.port=8888### xxl-job executor log-pathxxl.job.executor.logpath=/data/applogs/xxl-job/jobhandler### xxl-job executor log-retention-daysxxl.job.executor.logretentiondays=30@Componentpublic class XxlJobTaskExample { @XxlJob("blogJobHandler") public ReturnT<String> blogJobHandler(String param) throws Exception { System.out.println("執行"); XxlJobLogger.log("XXL-JOB, Hello World."); for (int i = 0; i < 5; i++) { XxlJobLogger.log("beat at:" + i); TimeUnit.SECONDS.sleep(2); } return ReturnT.SUCCESS; }}分別如下所示:
@Configuration@EnableSchedulerLock(defaultLockAtMostFor = "PT30M")public class ShedLockConfig { @Bean public LockProvider lockProvider(RedisTemplate redisTemplate) { return new RedisLockProvider(redisTemplate.getConnectionFactory()); }}@Componentpublic class TaskSchedule { /** * 每分鐘執行一次 * [秒] [分] [小時] [日] [月] [周] [年] */ @Scheduled(cron = "1 * * * * ?") @SchedulerLock(name = "synchronousSchedule") public void SynchronousSchedule() { System.out.println("Start run schedule to synchronous data:" + new Date()); }}@SpringBootApplication@EnableSchedulingpublic class ShedLockRedisApplication { public static void main(String[] args) { SpringApplication.run(ShedLockRedisApplication.class); }}server: tomcat: uri-encoding: UTF-8 max-threads: 1000 min-spare-threads: 30 port: 8083spring: redis: database: 0 host: localhost port: 6379 password: # 密碼（預設為空） timeout: 6000ms # 連線超時時長（毫秒） jedis: pool: max-active: 1000 # 連線池最大連線數（使用負值表示沒有限制） max-wait: -1ms # 連線池最大阻塞等待時間（使用負值表示沒有限制） max-idle: 10 # 連線池中的最大空閒連線 min-idle: 5 # 連線池中的最小空閒連線我之所以用shedlock是因為確保在叢集環境下各微服務的定時任務只執行一個，而不是全部都執行相同的定時任務。
本次測試效果如下:
本次程式碼例子已放至我的GitHub:
https://github.com/developers-youcong/blog-jobsource: https://developers-youcong.github.io/2020/11/21/Java之定時任務全家桶/
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