Using JXLS for Complex Excel Export in Java Backend Applications

When simple Excel exports can be handled by POI or EasyExcel, complex requirements—fixed styles, merged cells, dynamic columns—often demand more effort; JXLS, a lightweight Java library, addresses these challenges.

JXLS official site: https://jxls.sourceforge.net/

Adding Maven Dependencies

<!-- Version may vary; using 2.11.0 as example -->
<dependency>
<groupId>org.jxls</groupId>
<artifactId>jxls</artifactId>
<version>2.11.0</version>
</dependency>
<dependency>
<groupId>org.jxls</groupId>
<artifactId>jxls-poi</artifactId>
<version>2.11.0</version>
</dependency>
<!-- For JavaExcelAPI‑based converter -->
<dependency>
<groupId>org.jxls</groupId>
<artifactId>jxls-jexcel</artifactId>
<version>${jxlsJexcelVersion}</version>
</dependency>

Backend Utility Class

public static void exportExcel(InputStream is, OutputStream os, Map<String, Object> model) throws IOException {
Context context = new Context();
if (model != null) {
for (String key : model.keySet()) {
context.putVar(key, model.get(key));
}
}
JxlsHelper jxlsHelper = JxlsHelper.getInstance();
Transformer transformer = jxlsHelper.createTransformer(is, os);
JexlExpressionEvaluator evaluator = (JexlExpressionEvaluator) transformer.getTransformationConfig().getExpressionEvaluator();
Map<String, Object> funcs = new HashMap<>();
funcs.put("utils", new JxlsUtils()); // add custom functions
evaluator.setJexlEngine(new JexlBuilder().namespaces(funcs).create());
jxlsHelper.processTemplate(context, transformer);
}

Export Controller

// Example controller method
@PostMapping("/export/exportTradeCreditData")
@ResponseBody
public void exportTradeCreditData(HttpServletRequest request, HttpServletResponse response, Date countDate) {
String templatePath = "template/excel/trade_credit_data.xlsx";
URL templateResource = PathTools.findResource(templatePath);
try (OutputStream out = response.getOutputStream();
InputStream templateStream = templateResource.openStream()) {
List<CindaTradeCreditDto> list = countingReportService.queryTradeCreditData(countDate);
Map<String, Object> map = new HashMap<>();
map.put("year", getYear(countDate));
map.put("contracts", list);
JxlsUtils.exportExcel(templateStream, out, map);
out.close();
} catch (Exception e) {
e.printStackTrace();
log.error("导出excel异常, {}", JxlsUtils.executeException(e));
}
}

Creating the Excel Template

Use an .xlsx workbook (not .xls ) and design the sheet layout according to export requirements; only simple header/row styling, column/row sizes, and cell merging are supported. Insert JXLS expressions as cell comments (Shift+F2 in Office).

XLS Expressions

jx:area

jx:area(lastCell = "H3")

The jx:area command defines the rectangular region (from A1 to the specified last cell) that JXLS will parse, improving processing speed.

jx:each (most common)

jx:each(items="contracts" var="contract" lastCell="H3")

items : name of the collection in the context.

var : variable name for each element during iteration.

area : the parsing region for this command.

direction : fill direction, default DOWN .

select : optional filter expression.

For horizontal (dynamic column) iteration, set direction="RIGHT" :

jx:each(items="countMonths" var="month" lastCell="C3" direction="RIGHT")

jx:mergeCells

jx:mergeCells(lastCell="合并单元格范围" [, cols="合并的列数"] [, rows="合并的行数"] [, minCols="要合并的最小列数"] [, minRows="要合并的最小行数"])

This command merges cells only if they have not been merged previously.

Dynamic Columns – Combined Usage

jx:each(items="countMonths" var="month" lastCell="C3" direction="RIGHT")

In the template, use expressions such as ${empty(colData.monthData.get(month)) ? 0 : colData.monthData.get(month)} to safely output values for each dynamic column.

Summary

The above snippets demonstrate the most frequently used JXLS operations for exporting complex Excel reports, including Maven setup, backend utility methods, controller integration, template preparation, and key XLS expressions for areas, loops, cell merging, and dynamic columns.