每天上午 09.30 开始的 Cron 表达式，间隔 30 分钟

Question

我希望我的计划作业每天在特定时间和特定时间间隔运行。

例如，从上午 09.30 到晚上 11.30 的间隔为 30 分钟。

开始时间、结束时间和间隔可在运行时配置。

我尝试使用以下 cron 表达式：0 30/30 09-23 1/1 *？

但每小时运行一次，而不是每 30 分钟运行一次。

如果 cronexpress 无法实现，那么请使用 java 来实现它。

注意：开始时间、结束时间和间隔必须在运行时配置

Answer 1

我知道这已经很晚了，但最终可能会帮助别人。您实际上并不需要多个表达式来实现您的目标。

0,30 9-13 * * MON-FRI // Every 30 mins from 9:00AM to 1:30PM weekdays
30 9-13 * * MON-FRI // Every 30 mins from 9:30AM to 1:30PM weekdays

Answer 2

正如评论中已经指出的，您可能需要多个表达式。假设您将间隔限制为 60 倍（即 1,2,3,4,5,6,10,15,20,30,60），您应该需要 1 到 3 个表达式。

示例：如果您说从 9:45 到 23:15 每 5 分钟一次，则需要以下表达式：

0   45/5      9 * * ?   //every 5 minutes from 9:45 to 9:59
0    0/5  10-22 * * ?   //every 5 minutes from 10:00 to 22:59
0 0-15/5     23 * * ?   //every 5 minutes from 23:00 to 23:15

您应该能够仅根据您获得的数据来计算出该值。这是一个帮助您入门的快速技巧：

public static List<String> getExpressions( int startHour, int startMinute, int endHour, int endMinute, int interval) {
  List<String> expressions = new ArrayList<>();

  //If the start minute is greater than the interval we need a separate expression for the first hour
  if( startMinute >= interval ) {     
    expressions.add( String.format( "0 %d/%d %d * * ?", startMinute, interval, startHour ) );

    //the main expression needs to start as early as possible in the second hour, 
    //e.g. if you start at 9:33 and have 5 minute intervals it would need to start at 10:03  (9+1 = 10, 33%5 = 3)
    startMinute %= interval;
    startHour++;
  }

  //If the end minute is lower than the last run in the end hour we need a separate epxression for the last hour
  if( endMinute < (  startMinute + 60 - interval ) ) {     
    expressions.add( String.format( "0 %d-%d/%d %d * * ?", startMinute, endMinute, interval, endHour ) );

    //the main expression needs to run up to the second to last hour
    endHour--;
  }

  //if the main expression would still be 2+ hours in length
  if( startHour < endHour ) {        
    expressions.add( String.format( "0 %d/%d %d-%d * * ?", startMinute, interval, startHour, endHour ) );
  }
  //if the main expression is only 1 hour long don't use x-x
  else if ( startHour == endHour ) {
    expressions.add( String.format( "0 %d/%d %d * * ?", startMinute, interval, startHour ) );
  }

  return expressions;
}