Spring Batch - Map and Write 1->Many rows - spring-batch

Question

I have a spreadsheet that looks like so...
US LC US MC
40 55.39 3.26
39 54.39 1.26
This is it's POJO:
#Data
public class ExcelObject {
private BigDecimal timePeriod;
private BigDecimal usLc;
private BigDecimal usMc;
}
I need to transform this sheet and save it to the database like so...
TIME_PERIOD, LABEL, ALLOCATION
40, "US LC", 55.39
40, "US MC", 3.26
39, "US LC", 54.39
39, "US MC", 1.26
This is the POJO for the transformed ExcelObject:
#Data
public class ExcelItem {
private BigDecimal timePeriod;
private String label;
private BigDecimal allocation;
}
What's the best Spring Batch strategy to accomplish this transformation? I have a row mapper to map the data as-is from the spreadsheet. I was thinking in my processor I'd make the transformation. But how do I return 4 results from the processor, and write 4 rows? Thanks.

Answer 1

Implement an ItemReader to read ExcelObject :
public class MyItemReader implements ItemReader<ExcelObject> {
#Override
ExcelObject read() {
}
}
Then an ItemProcessor to convert ExcelObject to a List<ExcelItem> :
public class MyItemProcessor implements ItemProcessor<ExcelObject,List<ExcelItem>> {
#Override
List<ExcelItem> process(ExcelObject){
}
}
Finally , an ItemWriter to write List<ExcelItem>. In the writer , you can loop the items and reuse an existing ItemWriter provided by spring-batch and delegate to it for writing an item such as :
public class MyItemWriter implements ItemWriter<List<ExcelItem>> {
#Autowired
private JdbcBatchItemWriter<ExcelItem> jdbcWriter;
#Override
public void write(List<List<ExcelItem>> items) throws Exception {
for(List<ExcelItem> item : items){
jdbcWriter.writer(item);
}
}
}