Routing data to multiple files in item writer based on item's property as criteria

Question

I am getting a list of items in my reader.

There is a property called Code in each item object having several possible values not known to me before hand.

1) Based on the value of Codein each item, I want to write that particular item in a output file pertaining to that Code. For e.g. if my current item's Code is "abc", the item should be written in to abc.txt in the writer.

2) If there is a Code "xyz" in current item, for which the file is not present, a new file should get created and the item should go to that file.

3) For all such multiple files created based on Code, I also want to add a header and footer call back to enter some details e.g. count of items in each file.

Is it possible to have a writer, which satisfies above 3 requirements ?

I know that using multiresourceitemwriter, one can divide the data among multiple output files. But as far as I know, this division is based on the number of items. For e.g. first 10 items in file1, next 10 in file2 and so on.

But how to route data to output files based on an item property as mentioned in my question ?

I am well acquainted with Spring Batch and just need a little guidance since this is the first time I am facing this kind of issue.

Thanks for reading!

Answer 1

i would try it with at least 2 strategies

1. the batch writes all data into a temporary database table and simple tool/batch/script creates the individual files - i'm not sure about header/footer but as always one could say "let's keep it cheap"
2. the itemWriter creates and manages the needed writers on the fly, maybe with an abstract pre-configured writer/bean as template, as long as you ignore restart scenarios it sounds "easy"