Saving and accessing number of rows retrieved by JdbcCursorItemReader

Question

Our Spring Batch application has:a custom JdbcCursorItemReader which reads from the database, and a custom JmsItemWriter, which enables headers to added to each message.

The idea is that each message will have a correlation id and be part of a set. Within the JmsItemWriter, we need to access the total number of rows which the item reader retrieved.

What is the best approach to do this?

Thanks

Luca Basso Ricci · Answer 1 · 2014-04-29T15:00:23.830

0

If you need to access the TOTAL count of rows (eg the select count(*) from table) the best choice is to create a previous step where you perform the count and put the result into execution-context to access it in next steps.
If you need the number of current record JdbcCursorItemReader inherits this facilities from AbstractItemCountingItemStreamItemReader

edited Apr 29 '14 at 15:00

answered Apr 29 '14 at 14:04

Luca Basso Ricci

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Thanks very much. What is the best way to access the execution context from an ItemProcessor or ItemWriter ? – user1052610 Apr 29 '14 at 15:00
look at http://stackoverflow.com/questions/22205778/what-are-the-spring-batch-default-context-variables/22208521#22208521 – Luca Basso Ricci Apr 29 '14 at 15:31
Thanks for all your help. Would this work (and avoid having both to have an extra step and to hit the DB with an extra query): 1. Create a custom JdbcCursorItemReader 2. Inject into it the execution context ( – user1052610 Apr 30 '14 at 12:10
Maybe.You have to try. But I prefer an extra step because I think it is more readable (or implement `StepExecutionListener.beforeStep()` to perform `select count` if you don't want to create an extra step) – Luca Basso Ricci Apr 30 '14 at 12:14
Thanks. Here is what I am not understanding: how from an item writer, processor or reader, to get hold of the StepExecutionContext itself so as to then add a variable to it (as opossed to getting the value of a variable which is already in it). Is that possible? – user1052610 May 01 '14 at 13:42
Use listeners. Or extend or delegate reader, writer or processor – Luca Basso Ricci May 01 '14 at 14:32
When extending reader, writer or processor, what base class functionality exposes the stepExecutionListener ? – user1052610 May 01 '14 at 18:58
sir, I'm not a human javadoc ;) I answered your question and more... please read official documentation at http://docs.spring.io/spring-batch/reference/html/ about listeners – Luca Basso Ricci May 01 '14 at 19:04
Great - implement ItemStream - very much appreciated. – user1052610 May 01 '14 at 19:11

score 0 · Answer 2 · answered Jul 20 '20 at 15:34

Easiest way is to use the StepListener, see following example :

@Component
public class StepListener extends StepExecutionListenerSupport {

  @Override
  public ExitStatus afterStep(StepExecution stepExecution) {
    // here, you can debug stepExecution to get some values like "readCount" :
    logger.info(stepExecution.getReadCount());

    // you also have commitCount, writeCount, rollbackCount, readSkipCount, writeSkipCount, processSkipCount, filterCount

    // check stepExecution.getSummary for a nice one line info
    logger.info(stepExecution.getSummary());

    return null;
  }
}

Don't forget to configure your stepListener in the Step of the Batch configuration

Saving and accessing number of rows retrieved by JdbcCursorItemReader

2 Answers2