Java export to Excel tool: JXLS

Introduction
Introduce maven dependencies
code behind
Create template
XLS expression
- jx:area
- jx:each is the most commonly used xls expression
- jx:mergeCells merge cells
- Dynamic columns-comprehensive use
Summarize

Introduction

I believe that everyone can often encounter the export of various excels on projects. Simple excel formats can be exported using simple poi, easyExcel and other tools. However, for complex Excel, there are various requirements such as fixed styles, merged cells, dynamic columns, etc., resulting in Excel export requiring a lot of effort to write code. jxls solves the above problems to a large extent.

Here is a brief introduction to jxls. JXLS is a simple, lightweight excel export library abroad. Link: JXLS official website. Here is a detailed documentation tutorial (English version). For your convenience, I will give some common excel examples. Template configuration is convenient for everyone to use.

https://jxls.sourceforge.net/

Introduce maven dependencies

<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>


<dependency>
    <groupId>org.jxls</groupId>
    <artifactId>jxls-jexcel</artifactId>
    <version>${jxlsJexcelVersion}</version>
</dependency>

code behind

Tool class: JxlsUtils, export static methods

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<String, Object>();
  funcs.put("utils", new JxlsUtils()); // 添加自定义功能
  evaluator.setJexlEngine(new JexlBuilder().namespaces(funcs).create());
  jxlsHelper.processTemplate(context, transformer);
 }

Export controller

//导出示例Controller
@PostMapping("/export/exportTradeCreditData")
@ResponseBody
public void exportTradeCreditData(HttpServletRequest request, HttpServletResponse response, Date countDate) {
  String templatePath = "template/excel/trade_credit_data.xlsx";
        //查找模板文件路径，这里PathTools类为系统内部封装类，大家注意copy
  URL templateResource = PathTools.findResource(templatePath);
  try (OutputStream out = response.getOutputStream();
    InputStream templateStream = templateResource.openStream();) {
            //业务数据查询
   List<CindaTradeCreditDto> list = countingReportService.queryTradeCreditData(countDate);
 
            //excel模板内，数据组装
   Map<String, Object> map = new HashMap<String, Object>();
   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));
  }
 }

Create template

Note: The excel template worksheet must use xlsx format, do not use xls format, to prevent data conversion errors during export

Create a new excel template in xlsx format
Set the table style in the worksheet according to the export requirements
Limited to simple table headers and row and column widths and heights
Write an expression, right-click on the worksheet to insert a comment, and add the comment shortcut key (Shit + F2) in the office
Set areas, data rows, merged cells, dynamic columns, etc.

XLS expression

A brief list of several commonly used expressions

jx:area

jx:area(lastCell = "H3")

XLS Area is an important concept in JxlsPlus. It indicates the rectangular area in the excel template that needs to be parsed, represented by A1 to the last cell, which is helpful to speed up parsing. It needs to be defined in the first cell (A1) of the excel template.

sample graph:

jx:each is the most commonly used xls expression

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

items: variable name of the collection in the context;
var: the variable name of each record when traversing the collection;
area: the parsing area of the XLS Command;
direction: the direction in which data is filled in excel, the default (DOWN) is downward;
select: its value is an expression, used to filter data

Note: If it involves dynamic columns and horizontal traversal, you need to pay attention to its usage, especially the data display issues of dynamic columns, which will be discussed below.

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

Simple example diagram:

Complex example diagram:

jx:mergeCells merge cells

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"]
)

lastCell: merge cell range;
cols: number of columns to be merged;
rows: number of merged rows;
minCols: the minimum number of columns to be merged;
minRows: the minimum number of rows to be merged;

Note: This command can only be used on cells that have not yet been merged.

sample graph:

Dynamic columns-comprehensive use

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

It is still used here through jx:each. The difference is that the value of the direction attribute is: RIGHT (to the right), and the default is: DOWN (downward).

Example screenshot:

Description of several parameters in the screenshot above:

countMonths: dynamic column collection, month is the entity of the collection cycle, the value is: ${month}
contracts: row data collection, contract, colData are entities of the collection cycle, the values are: ${contract.custName}, etc.
colData.monthData.get(month): Dynamic column data, matching entity fields based on column names
${empty()}: Determine whether the dynamic column data corresponding to the set is empty, make a good judgment, and write the data

Data acquisition for dynamic column data rows:

${empty(colData.monthData.get(month) ) ? 0 : colData.monthData.get(month)}