我以為動態停啟定時任務一般用quartz，沒想到還可以通過ScheduledTaskRegistrar來拓展。但是分散式場景，建議還是用quartz吧！

在 spring boot 專案中，可以通過 @EnableScheduling 註解和 @Scheduled 註解實現定時任務，也可以通過 SchedulingConfigurer 介面來實現定時任務。但是這兩種方式不能動態新增、刪除、啟動、停止任務。要實現動態增刪啟停定時任務功能，比較廣泛的做法是整合 Quartz 框架。

但是本人的開發原則是：在滿足專案需求的情況下，儘量少的依賴其它框架，避免專案過於臃腫和複雜。檢視 spring-context 這個 jar 包中 org.springframework.scheduling.ScheduledTaskRegistrar 這個類的原始碼，發現可以通過改造這個類就能實現動態增刪啟停定時任務功能。

定時任務列表頁

定時任務執行日誌

新增執行定時任務的執行緒池配置類

@Configuration
public class SchedulingConfig {
 @Bean
 public TaskScheduler taskScheduler() {
  ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();
  
  taskScheduler.setPoolSize(4);
  taskScheduler.setRemoveOnCancelPolicy(true);
  taskScheduler.setThreadNamePrefix("TaskSchedulerThreadPool-");
  return taskScheduler;
 }
}

新增 ScheduledFuture 的包裝類。ScheduledFuture 是 ScheduledExecutorService 定時任務執行緒池的執行結果。

public final class ScheduledTask {

 volatile ScheduledFuture<?> future;

 
 public void cancel() {
  ScheduledFuture<?> future = this.future;
  if (future != null) {
   future.cancel(true);
  }
 }
}

新增 Runnable 介面實現類，被定時任務執行緒池呼叫，用來執行指定 bean 裡面的方法。

public class SchedulingRunnable implements Runnable {

 private static final Logger logger = LoggerFactory.getLogger(SchedulingRunnable.class);

 private String beanName;

 private String methodName;

 private String params;

 public SchedulingRunnable(String beanName,String methodName) {
  this(beanName,methodName,null);
 }

 public SchedulingRunnable(String beanName,String methodName,String params) {
  this.beanName = beanName;
  this.methodName = methodName;
  this.params = params;
 }

 @Override
 public void run() {
  logger.info("定時任務開始執行 - bean：{}，方法：{}，引數：{}",beanName,params);
  long startTime = System.currentTimeMillis();

  try {
   Object target = SpringContextUtils.getBean(beanName);

   Method method = null;
   if (StringUtils.isNotEmpty(params)) {
    method = target.getClass().getDeclaredMethod(methodName,String.class);
   } else {
    method = target.getClass().getDeclaredMethod(methodName);
   }

   ReflectionUtils.makeAccessible(method);
   if (StringUtils.isNotEmpty(params)) {
    method.invoke(target,params);
   } else {
    method.invoke(target);
   }
  } catch (Exception ex) {
   logger.error(String.format("定時任務執行異常 - bean：%s，方法：%s，引數：%s ",params),ex);
  }

  long times = System.currentTimeMillis() - startTime;
  logger.info("定時任務執行結束 - bean：{}，方法：{}，引數：{}，耗時：{} 毫秒",params,times);
 }

 @Override
 public boolean equals(Object o) {
  if (this == o) return true;
  if (o == null || getClass() != o.getClass()) return false;
  SchedulingRunnable that = (SchedulingRunnable) o;
  if (params == null) {
   return beanName.equals(that.beanName) &&
     methodName.equals(that.methodName) &&
     that.params == null;
  }

  return beanName.equals(that.beanName) &&
    methodName.equals(that.methodName) &&
    params.equals(that.params);
 }

 @Override
 public int hashCode() {
  if (params == null) {
   return Objects.hash(beanName,methodName);
  }

  return Objects.hash(beanName,params);
 }
}

新增定時任務註冊類，用來增加、刪除定時任務。

@Component
public class CronTaskRegistrar implements DisposableBean {

 private final Map<Runnable,ScheduledTask> scheduledTasks = new ConcurrentHashMap<>(16);

 @Autowired
 private TaskScheduler taskScheduler;

 public TaskScheduler getScheduler() {
  return this.taskScheduler;
 }

 public void addCronTask(Runnable task,String cronExpression) {
  addCronTask(new CronTask(task,cronExpression));
 }

 public void addCronTask(CronTask cronTask) {
  if (cronTask != null) {
   Runnable task = cronTask.getRunnable();
   if (this.scheduledTasks.containsKey(task)) {
    removeCronTask(task);
   }

   this.scheduledTasks.put(task,scheduleCronTask(cronTask));
  }
 }

 public void removeCronTask(Runnable task) {
  ScheduledTask scheduledTask = this.scheduledTasks.remove(task);
  if (scheduledTask != null)
   scheduledTask.cancel();
 }

 public ScheduledTask scheduleCronTask(CronTask cronTask) {
  ScheduledTask scheduledTask = new ScheduledTask();
  scheduledTask.future = this.taskScheduler.schedule(cronTask.getRunnable(),cronTask.getTrigger());

  return scheduledTask;
 }


 @Override
 public void destroy() {
  for (ScheduledTask task : this.scheduledTasks.values()) {
   task.cancel();
  }

  this.scheduledTasks.clear();
 }
}

新增定時任務示例類

@Component("demoTask")
public class DemoTask {
 public void taskWithParams(String params) {
  System.out.println("執行有參示例任務：" + params);
 }

 public void taskNoParams() {
  System.out.println("執行無參示例任務");
 }
}

定時任務資料庫表設計

定時任務資料庫表設計

新增定時任務實體類

public class SysJobPO {
 
 private Integer jobId;
 
 private String beanName;
 
 private String methodName;
 
 private String methodParams;
 
 private String cronExpression;
 
 private Integer jobStatus;
 
 private String remark;
 
 private Date createTime;
 
 private Date updateTime;

 public Integer getJobId() {
  return jobId;
 }

 public void setJobId(Integer jobId) {
  this.jobId = jobId;
 }

 public String getBeanName() {
  return beanName;
 }

 public void setBeanName(String beanName) {
  this.beanName = beanName;
 }

 public String getMethodName() {
  return methodName;
 }

 public void setMethodName(String methodName) {
  this.methodName = methodName;
 }

 public String getMethodParams() {
  return methodParams;
 }

 public void setMethodParams(String methodParams) {
  this.methodParams = methodParams;
 }

 public String getCronExpression() {
  return cronExpression;
 }

 public void setCronExpression(String cronExpression) {
  this.cronExpression = cronExpression;
 }

 public Integer getJobStatus() {
  return jobStatus;
 }

 public void setJobStatus(Integer jobStatus) {
  this.jobStatus = jobStatus;
 }

 public String getRemark() {
  return remark;
 }

 public void setRemark(String remark) {
  this.remark = remark;
 }

 public Date getCreateTime() {
  return createTime;
 }

 public void setCreateTime(Date createTime) {
  this.createTime = createTime;
 }

 public Date getUpdateTime() {
  return updateTime;
 }

 public void setUpdateTime(Date updateTime) {
  this.updateTime = updateTime;
 }
}

新增定時任務

新增定時任務

boolean success = sysJobRepository.addSysJob(sysJob);
if (!success)
 return OperationResUtils.fail("新增失敗");
else {
 if (sysJob.getJobStatus().equals(SysJobStatus.NORMAL.ordinal())) {
  SchedulingRunnable task = new SchedulingRunnable(sysJob.getBeanName(),sysJob.getMethodName(),sysJob.getMethodParams());
  cronTaskRegistrar.addCronTask(task,sysJob.getCronExpression());
 }
}

return OperationResUtils.success();

修改定時任務，先移除原來的任務，再啟動新任務

boolean success = sysJobRepository.editSysJob(sysJob);
if (!success)
 return OperationResUtils.fail("編輯失敗");
else {
 
 if (existedSysJob.getJobStatus().equals(SysJobStatus.NORMAL.ordinal())) {
  SchedulingRunnable task = new SchedulingRunnable(existedSysJob.getBeanName(),existedSysJob.getMethodName(),existedSysJob.getMethodParams());
  cronTaskRegistrar.removeCronTask(task);
 }

 if (sysJob.getJobStatus().equals(SysJobStatus.NORMAL.ordinal())) {
  SchedulingRunnable task = new SchedulingRunnable(sysJob.getBeanName(),sysJob.getCronExpression());
 }
}

return OperationResUtils.success();

刪除定時任務

boolean success = sysJobRepository.deleteSysJobById(req.getJobId());
if (!success)
 return OperationResUtils.fail("刪除失敗");
else{
 if (existedSysJob.getJobStatus().equals(SysJobStatus.NORMAL.ordinal())) {
  SchedulingRunnable task = new SchedulingRunnable(existedSysJob.getBeanName(),existedSysJob.getMethodParams());
  cronTaskRegistrar.removeCronTask(task);
 }
}

return OperationResUtils.success();

定時任務啟動 / 停止狀態切換

if (existedSysJob.getJobStatus().equals(SysJobStatus.NORMAL.ordinal())) {
 SchedulingRunnable task = new SchedulingRunnable(existedSysJob.getBeanName(),existedSysJob.getMethodParams());
 cronTaskRegistrar.addCronTask(task,existedSysJob.getCronExpression());
} else {
 SchedulingRunnable task = new SchedulingRunnable(existedSysJob.getBeanName(),existedSysJob.getMethodParams());
 cronTaskRegistrar.removeCronTask(task);
}

新增實現了 CommandLineRunner 介面的 SysJobRunner 類，當 spring boot 專案啟動完成後，載入資料庫裡狀態為正常的定時任務。

@Service
public class SysJobRunner implements CommandLineRunner {

 private static final Logger logger = LoggerFactory.getLogger(SysJobRunner.class);

 @Autowired
 private ISysJobRepository sysJobRepository;

 @Autowired
 private CronTaskRegistrar cronTaskRegistrar;

 @Override
 public void run(String... args) {
  
  List<SysJobPO> jobList = sysJobRepository.getSysJobListByStatus(SysJobStatus.NORMAL.ordinal());
  if (CollectionUtils.isNotEmpty(jobList)) {
   for (SysJobPO job : jobList) {
    SchedulingRunnable task = new SchedulingRunnable(job.getBeanName(),job.getMethodName(),job.getMethodParams());
    cronTaskRegistrar.addCronTask(task,job.getCronExpression());
   }

   logger.info("定時任務已載入完畢...");
  }
 }
}

工具類 SpringContextUtils，用來從 spring 容器裡獲取 bean

@Component
public class SpringContextUtils implements ApplicationContextAware {

 private static ApplicationContext applicationContext;

 @Override
 public void setApplicationContext(ApplicationContext applicationContext)
   throws BeansException {
  SpringContextUtils.applicationContext = applicationContext;
 }

 public static Object getBean(String name) {
  return applicationContext.getBean(name);
 }

 public static <T> T getBean(Class<T> requiredType) {
  return applicationContext.getBean(requiredType);
 }

 public static <T> T getBean(String name,Class<T> requiredType) {
  return applicationContext.getBean(name,requiredType);
 }

 public static boolean containsBean(String name) {
  return applicationContext.containsBean(name);
 }

 public static boolean isSingleton(String name) {
  return applicationContext.isSingleton(name);
 }

 public static Class<? extends Object> getType(String name) {
  return applicationContext.getType(name);
 }
}

總結

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