The problem is that I can't select just what I need off the tables, a part of the business logic is to do some field compares in order to determine which records need to be written for this customer. My plan was to select off all the keys needed, then let the item processor get all the rows involved for the given key, compare and apply the business logic to determine which if any of the records need written then pass a List of records.

I achieved this by creating a new writer from the BeanIOItemWriter and modifying the following method -

@Override

  public void writeItems(final List<Object> items) throws Exception {

  for (final Object e : items) {

  System.out.println(e.getClass().getName() + " -> " + e);

  if (e instanceof Collection) {

  for (Object o : ((Collection<?>) e)) {

  beanWriter.write(o);

  }

  } else {

  beanWriter.write(e);

  }

  }

  }

I like the ItemWriteListener idea. I set one up and have a question.

1. Reads input, which contains 2 records.
2. The item processor takes each input records and performs additional business logic to create a List of records to be written. The first input record becomes a List of 4 records, the second becomes a List of 2 records.
3. The write listener (below) converts the container/list and the writer writes a total of 6 records, as expected.
4. The step listener display the metrics but it only shows a WRITE_COUNT of 2, I was expecting 6.

Is there something I can do to ensure the write count matches the file's record count?

Step listener's afterStep() contains the following -

for (Metric metric : stepContext.getMetrics()) {

   log.info("Metric " + metric.getType() + "=" + metric.getValue());

}

import java.util.ArrayList;

import java.util.Collection;

import java.util.List;

import javax.batch.api.chunk.listener.ItemWriteListener;

public class CollectionTestWriteListener implements ItemWriteListener {

  @Override

  public void afterWrite(List<Object> arg0) throws Exception {

  }

  @Override

  public void beforeWrite(List<Object> arg0) throws Exception {

  List<Object> list = new ArrayList<Object>();

  for (Object o : arg0) {

  if (o instanceof Collection) {

  list.addAll((Collection<?>) o);

  } else {

  list.add(o);

  }

  }

  arg0.clear();

  arg0.addAll(list);

  }

  @Override

  public void onWriteError(List<Object> arg0, Exception arg1) throws Exception {

  }

}

I do cache any metrics but rely on the following -

Step listener's afterStep() contains the following -

for (Metric metric : stepContext.getMetrics()) {

   log.info("Metric " + metric.getType() + "=" + metric.getValue());

}