Hibernate Batch export problem example

hibernate_csv_export.java

public class ExportCSV extends ApplicationContextAwareTest {
	private static final Logger logger = LoggerFactory.getLogger(ExportCSV.class);
	
	@Autowired
	private TaxRollRecordDAO taxRollRecordDAO;

	String query = "from TaxRollRecord r order by r.id";

	String countQuery = "select count(r) from TaxRollRecord r";
	
	@Test
	public void doExport() {
		Long count = taxRollRecordDAO.getCount(countQuery);

		logger.debug("Exporting {} records", count);

		int offset = 0;
		int limit = 5000;

		CSVWriter writer = null;

		try {
			writer = new CSVWriter(new FileWriter("tax_roll_export.csv"), '\t');

			writer.writeNext(headerRow());

			while (true) {
				logger.debug("Processing offset '{}' of '{}'", offset, count);

				List<TaxRollRecord> data = taxRollRecordDAO.find(query, offset, limit);

				for (TaxRollRecord record : data) {
					String[] line = toLine(record);
					writer.writeNext(line);
				}

				if (data.size() < limit) {
					break;
				}

				offset += limit;
			}
		}
		catch (Exception e) {
			logger.error("Error writing CSV file", e);
		}
		finally {
			IOUtils.closeQuietly(writer);
		}

	}

	private String[] toLine(TaxRollRecord record) {
		List<String> line = new ArrayList<String>(24);
		line.add(record.getCity());
		line.add(record.getState());
		line.add(record.getZip());
		line.add(ObjectUtils.toString(record.getBeds()));
		line.add(ObjectUtils.toString(record.getBaths()));
		line.add(ObjectUtils.toString(record.getYearBuilt()));
		line.add(ObjectUtils.toString(record.getAdjustedBuildingSqft()));
		line.add(ObjectUtils.toString(record.getSaleDate1()));
		line.add(ObjectUtils.toString(record.getSalePrice1()));
		line.add(ObjectUtils.toString(record.getSaleDate2()));
		line.add(ObjectUtils.toString(record.getSalePrice2()));
		line.add(ObjectUtils.toString(record.getSaleDate3()));
		line.add(ObjectUtils.toString(record.getSalePrice3()));
		line.add(ObjectUtils.toString(record.getSaleDate4()));
		line.add(ObjectUtils.toString(record.getSalePrice4()));
		line.add(ObjectUtils.toString(record.getJustLandValue()));
		line.add(ObjectUtils.toString(record.getJustBuildingValue()));
		line.add(ObjectUtils.toString(record.getAssessedValue()));
		line.add(ObjectUtils.toString(record.getLastYearLandValue()));
		line.add(ObjectUtils.toString(record.getLastYearBuildingValue()));
		line.add(ObjectUtils.toString(record.getLastYearAssessedValue()));
		line.add(ObjectUtils.toString(record.getTwoYearsLandValue()));
		line.add(ObjectUtils.toString(record.getTwoYearsBuildingValue()));
		line.add(ObjectUtils.toString(record.getTwoYearsAssessedValue()));
		
		return line.toArray(new String[line.size()]);
	}

	private String[] headerRow() {
		List<String> line = new ArrayList<String>(24);
		line.add("city");
		line.add("state");
		line.add("zip");
		line.add("beds");
		line.add("baths");
		line.add("year_built");
		line.add("sqft");
		line.add("sale_date_1");
		line.add("sale_price_1");
		line.add("sale_date_2");
		line.add("sale_price_2");
		line.add("sale_date_3");
		line.add("sale_price_3");
		line.add("sale_date_4");
		line.add("sale_price_4");
		line.add("just_land_value");
		line.add("just_building_value");
		line.add("assessed_value");
		line.add("last_year_land_value");
		line.add("last_year_building_value");
		line.add("last_year_assessed_value");
		line.add("two_years_land_value");
		line.add("two_years_building_value");
		line.add("two_years_assessed_value");
		
		String[] arr = line.toArray(new String[line.size()]);
		line.clear();
		return arr;
	}

}



public interface GenericDAO<T, ID extends Serializable> {

	T findById(ID id, boolean lock);

	List<T> findAll();

	List<T> findByExample(T exampleInstance, String[] excludeProperty);

	T save(T entity);

	void makeTransient(T entity);

	List<T> find(final String query, final int offset, final int limit, final Object... values);

	public long getCount(final String query, final Object... values);

	public long getCount(final String query);
	
	public void flush();
	
	public void clear();
	
	public void evict(T entity);
}