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2之间的区别？

[英]Alfresco cron syntax: difference between 0/2 and */2?

原文 2017-12-15 12:55:04 2 1 java/ cron/ alfresco

Alfresco has a cron-like system that allows you to run a job at regular intervals. Alfresco具有类似cron的系统，可让您定期运行作业。 The documentation specifies as an example the expression 0 0/2 * * * ? 例如，文档指定表达式0 0/2 * * * ? which will make the job run every 2 minutes. 这会使作业每2分钟运行一次。 However, in a lot of code I see people using the expression 0 */2 * * * ? 但是，在很多代码中，我看到人们使用表达式0 */2 * * * ? instead, the difference being that the zero is replaced by an asterisk. 相反，区别在于零被星号代替。 This syntax is more similar to the syntax found in some Unix implementations of cron , but I don't think I can blindly assume they work the same (Alfresco's syntax has a seconds field that Unix syntax lacks, for instance). 这种语法与某些cron的Unix实现中的语法更相似，但我认为我不能盲目地假设它们的工作原理相同（例如，Alfresco的语法具有Unix语法缺少的秒字段）。

So my question is, is there any difference in functionality between the expression 0/2 and */2 ? 所以我的问题是，表达式0/2和*/2之间的功能是否有区别？ And as a followup, is there a place where Alfresco's syntax is properly documented? 作为后续，是否有适当的地方记录Alfresco的语法？

1 个解决方案

Oliver Charlesworth 's comment led me to the Quartz docs that contain the answer: Oliver Charlesworth的评论使我进入了包含答案的Quartz文档：

You can also specify '/' after the '*' character - in this case '*' is equivalent to having '0' before the '/'. 您也可以在'*'字符后指定'/'-在这种情况下，'*'等同于在'/'之前有'0'。

So 0/2 and */2 are equivalent cron expressions. 因此0/2和*/2是等效的cron表达式。