Scheduler pattern with JAVA: how to check if current date time matches pattern

I'm wondering how to do some pattern matching in JAVA for date time. I have a database which has some开发者_运维知识库 entries that need to be scheduled.

Basically, I have a program that runs each 30 minutes. Inside this program (I own the code) I want to do a check against the database records on a field (non existent yet) if the current date / time matches the record's scheduler.

Examples of scheduler option should be something like: - daily + given hour - weekly + given hour - monthly + given hour - each Monday or Tuesday or Wednesday or ... at given hour

How should I store the scheduler pattern value (string, datetime, ?) and do the comparison inside my JAVA code to see if it matches?

Thanks

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RFC 2445 should be useful to deal witch scheduling and recurrence. Here is a java library http://code.google.com/p/google-rfc-2445/.

You could store recurrence rules as a text in RRULE format, then parse it with the library to calculate the next recurrence date/time.

It should also be useful to change the app logic the other way around - to schedule execution at the specific calculated time, not to execute every 30 minutes trying to match the current time with recurrence patterns.