Spring Scheduler动态更改cron表达式

  • Z时代
  • 2024-01-10
  • 分类：问答

我能够在applicationContext.xml中创建taskScheduler，并且根据该cron属性定期触发我的工作。

我想cron在调度程序启动后更改此表达式（触发时间），这意味着JavaEE应用程序正在运行。

使用Spring 3.XX

回答：

其实我也遇到过同样的问题

我假设您需要从用户那里获取date（1-31），时间，星期几，调度程序的类型（每日，每月，每周）。

首先，您需要根据用户给定的日期时间创建cron表达式。以下代码将创建cron表达式，它需要一个映射并将cron表达式作为字符串返回。

public String  getCronExp(final Map<String, Object> configMap) {
    LOGGER.debug(">>  getCronExp");
    String exp = "";
    final String type = (String) configMap.get(SCHEDULER_TYPE);
    final String time = (String) configMap.get(TIME);
    final String[] split = time.split(this.COLON);
    String hour = split[0];
    String min = split[1];
    if ("00".equalsIgnoreCase(min)) {
        min = ZERO;
    }
    if ("00".equalsIgnoreCase(hour)) {
        hour = "0";
    }
    if ("daily".equalsIgnoreCase(type)) {
        exp = this.ZERO + this.WHITE_SPACE + min + this.WHITE_SPACE + hour + this.WHITE_SPACE + this.ASTERISK + this.WHITE_SPACE + this.ASTERISK
                + this.WHITE_SPACE + "?";
    } else if ("monthly".equalsIgnoreCase(type)) {
        final String date = (String) configMap.get(START_DATE);
        exp = this.ZERO + this.WHITE_SPACE + min + this.WHITE_SPACE + hour + this.WHITE_SPACE + date + this.WHITE_SPACE + this.ASTERISK + this.WHITE_SPACE
                + "?";
    } else if ("weekly".equalsIgnoreCase(type)) {
        final String dayOfWeek = (String) configMap.get(DAY_OF_WEEK);
        exp = this.ZERO + this.WHITE_SPACE + min + this.WHITE_SPACE + hour + this.WHITE_SPACE + "?" + this.WHITE_SPACE + this.ASTERISK + this.WHITE_SPACE
                + dayOfWeek;
    }
    LOGGER.info("Latest cron  expression scheduler " + exp);
    LOGGER.debug("<<  getCronExp");
    return exp;
}

在获得cron表达式后，就会出现触发调度程序的问题。

创建一个扩展可运行的类：

public  class Scheduler implements Runnable {
@SuppressWarnings("rawtypes")
ScheduledFuture scheduledFuture;
TaskScheduler taskScheduler ;
//this method will kill previous scheduler if exists and will create a new scheduler with given cron expression
public  void reSchedule(String cronExpressionStr){
 if(taskScheduler== null){
        this.taskScheduler = new ConcurrentTaskScheduler();
    }
     if (this.scheduledFuture() != null) {
        this.scheduledFuture().cancel(true);
    }
 this.scheduledFuture = this.taskScheduler.schedule(this, new CronTrigger(cronExpressionStr));
}
@Override
public  void run(){
// task to be performed 
}
//if you want on application to read data on startup from db and schedule the schduler use following method
 @PostConstruct
  public void initializeScheduler() {
    //@postcontruct method will be called after creating all beans in application context
    // read user config map from db 
    // get cron expression created 
    this.reSchedule(cronExp);
  }
}

以上是 Spring Scheduler动态更改cron表达式 的全部内容， 来源链接： utcz.com/qa/425668.html

回到顶部