To export data from a database query into an Excel file using Java, you can leverage Apache POI to generate the spreadsheet and populate it with query results.

public class DataExporter {

    @Autowired
    private RecordMapper recordMapper;

    public void exportToExcel() {
        File outputFile = new File("/home/vlog/report.xls");
        HSSFWorkbook workbook = new HSSFWorkbook();
        HSSFSheet sheet = workbook.createSheet("Report");

        // Create header row
        HSSFRow headerRow = sheet.createRow(0);
        HSSFCellStyle centerStyle = workbook.createCellStyle();
        centerStyle.setAlignment(HorizontalAlignment.CENTER);

        headerRow.createCell(0).setCellValue("Date");
        headerRow.createCell(1).setCellValue("Account");
        headerRow.createCell(2).setCellValue("Phone");

        List<Record> records = recordMapper.fetchRecords();
        if (!records.isEmpty()) {
            for (int i = 0; i < records.size(); i++) {
                HSSFRow dataRow = sheet.createRow(i + 1);
                Record current = records.get(i);

                if (current.getDate() != null) {
                    dataRow.createCell(0).setCellValue(current.getDate());
                }
                if (current.getAccount() != null) {
                    dataRow.createCell(1).setCellValue(current.getAccount());
                }
                if (current.getPhone() != null) {
                    dataRow.createCell(2).setCellValue(current.getPhone());
                }
            }
        }

        try (FileOutputStream fos = new FileOutputStream(outputFile)) {
            workbook.write(fos);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

The Record class represents the database table structure:

@Data
@Entity
@TableName("DATA_TABLE")
public class Record {
    private String date;
    private String account;
    private String phone;
}

The corresponding mapper interface defines the query method:

public interface RecordMapper {
    List<Record> fetchRecords();
}