背景

在使用easyexcel进行报表生成的时候，有需求要把字典数据塞到单元格中，easyexcel提供了一个直接生成下拉列表的方法，但是实际使用过程中，字典长度过长时，会导致下拉列表无数据的问题

环境

组件	版本
jdk	1.8
x-easypdf	2.10.0

最新插入下拉数据方法

先创建一个隐藏的字典sheet，在对应列中插入字典数据，在原sheet里根据列序号找到字典sheet中对应的字典数据，作为下拉列表

    /*** 处理下拉数据* @param sheet* @param cell*/private void handleDropDown(Sheet sheet, Cell cell) {String hiddenName = "hidden";Workbook workbook = sheet.getWorkbook();Sheet hidden = workbook.getSheet(hiddenName);if(ObjectUtils.isEmpty(hidden)) {hidden = workbook.createSheet(hiddenName);}// 设置隐藏workbook.setSheetHidden(workbook.getSheetIndex(hidden), true);DataValidationHelper helper = sheet.getDataValidationHelper();Map<String, Map<String, String>> rowColMap = new HashMap<>();Map<String, String> colReferMap = new HashMap<>();if(ObjectUtils.isEmpty(needPickData)) {return;}for (Integer k : needPickData.keySet()) {List<Object> v = needPickData.get(k);if(CollectionUtils.isEmpty(v)) {continue;}String excelLine = getExcelLine(k);List<Object> lists = v.stream().filter(ObjectUtils::isNotEmpty).distinct().collect(Collectors.toList());colReferMap.put(k.toString(), "=" + hiddenName + "!$" + excelLine +"$1:$" + excelLine + "$" + (lists.size()));if(CollectionUtils.isEmpty(lists)) {continue;}for (int i = 0; i < lists.size(); i++) {Map<String, String> colMap = rowColMap.containsKey(Integer.toString(i))?rowColMap.get(Integer.toString(i)):new HashMap<>();String value = lists.get(i).toString();colMap.put(k.toString(), value);rowColMap.put(Integer.toString(i), colMap);}}if(rowColMap.size()>0) {for (String rowNum : rowColMap.keySet().stream().sorted(Comparator.comparing(Integer::parseInt)).collect(Collectors.toList())) {Row row = hidden.createRow(Integer.parseInt(rowNum));if (rowColMap.get(rowNum).size() == 0) {continue;}for (String colNum : rowColMap.get(rowNum).keySet().stream().sorted(Comparator.comparing(Integer::parseInt)).collect(Collectors.toList())) {row.createCell(Integer.parseInt(colNum)).setCellValue(rowColMap.get(rowNum).get(colNum));}}}if(colReferMap.size()>0) {for (String colNum : colReferMap.keySet().stream().sorted(Comparator.comparing(Integer::parseInt)).collect(Collectors.toList())) {// 设置下拉列表的行： 首行，末行，首列，末列CellRangeAddressList addressList = new CellRangeAddressList(cell.getRowIndex(), 10000, Integer.parseInt(colNum), Integer.parseInt(colNum));DataValidationConstraint constraint = helper.createFormulaListConstraint(colReferMap.get(colNum));DataValidation dataValidation = helper.createValidation(constraint, addressList);sheet.addValidationData(dataValidation);}}}/***  返回excel列标A-Z-AA-ZZ* @param num 列数* @return java.lang.String*/public String getExcelLine ( int num){String line = "";int first = num / 26;int second = num % 26;if (first > 0) {line = (char) ('A' + first - 1) + "";}line += (char) ('A' + second) + "";return line;}

旧版插入下拉数据方法

缺陷：字典长度过长时，无法插入下拉列表

    /*** 处理下拉数据* @param sheet* @param cell*/@Deprecatedprivate void handleDropDownOld(Sheet sheet, Cell cell) {DataValidationHelper helper = sheet.getDataValidationHelper();needPickData.forEach((k, v) -> {// 设置下拉列表的行： 首行，末行，首列，末列CellRangeAddressList rangeList = new CellRangeAddressList(cell.getRowIndex(), 100000, k, k);// 设置下拉列表的值if (CollectionUtils.isNotEmpty(v)){List<Object> lists = v.stream().filter(ObjectUtils::isNotEmpty).distinct().collect(Collectors.toList());if(CollectionUtils.isNotEmpty(lists)) {String[] values = new String[lists.size()];for (int i = 0; i < lists.size(); i++) {values[i] = lists.get(i).toString();}DataValidationConstraint constraint = helper.createExplicitListConstraint(values);// 设置约束DataValidation validation = helper.createValidation(constraint, rangeList);// 阻止输入非下拉选项的值validation.setErrorStyle(DataValidation.ErrorStyle.STOP);validation.setShowErrorBox(true);validation.setSuppressDropDownArrow(true);validation.createErrorBox("提示", "请输入下拉选项中的内容");sheet.addValidationData(validation);}}});}