解决POI的SXSSFSheet 创建excel下拉框，下拉框内容过多时不显示的问题

1. 复现：使用POI导出带下拉框的excel文件，如果下拉框内容过多，下拉框变为了空
解决思路：导出时创建隐藏的sheet，下拉框的取值从隐藏的sheet中获取，下拉框显示正常
记录：因为网上的一些代码用的都不是SXSSFSheet创建所以拿过来都需要改，所以我把改好的代码贴上来，大家就不用修改了

代码：

    /*** @description: 解决下拉框过长不显示问题* @author: Johnny* @param workbook* @param sheet* @param intArr (开始行,结束行,下拉框所在的列)* @param deptList 下拉数据数组* @return: void**/public static void setLongHSSFValidation(XSSFWorkbook workbook, XSSFSheet sheet,Integer[] intArr, String[] deptList) {int firstRow = intArr[0];int endRow =intArr[1];int cellNum =intArr[2];String hiddenName = "hidden"+cellNum;//1.创建隐藏的sheet页。XSSFSheet hidden = workbook.createSheet(hiddenName);//2.循环赋值（为了防止下拉框的行数与隐藏域的行数相对应，将隐藏域加到结束行之后）for (int i = 0, length = deptList.length; i < length; i++) {hidden.createRow(endRow + i).createCell(cellNum).setCellValue(deptList[i]);}Name category1Name = workbook.createName();category1Name.setNameName(hiddenName);//3 A1:A代表隐藏域创建第N列createCell(N)时。以A1列开始A行数据获取下拉数组category1Name.setRefersToFormula(hiddenName + "!A1:A" + (deptList.length + endRow));//DataValidationHelper helper = sheet.getDataValidationHelper();DataValidationConstraint constraint = helper.createFormulaListConstraint(hiddenName);CellRangeAddressList addressList = new CellRangeAddressList(1, endRow, cellNum, cellNum);DataValidation dataValidation = helper.createValidation(constraint, addressList);if (dataValidation instanceof XSSFDataValidation) {// 数据校验dataValidation.setSuppressDropDownArrow(true);dataValidation.setShowErrorBox(true);} else {dataValidation.setSuppressDropDownArrow(false);}// 作用在目标sheet上sheet.addValidationData(dataValidation);// 设置hiddenSheet隐藏workbook.setSheetHidden(workbook.getSheetIndex(hiddenName), true);}

这是一般的下拉框代码，数据量少的时候可以用

/**有下拉框不显示的问题* 设置excel下拉框* @param sheet* @param textlist 下拉数据列表* @param firstRow* @param endRow* @param firstCol* @param endCol* @return*/public static XSSFSheet setHSSFValidation(XSSFSheet sheet,String[] textlist, int firstRow, int endRow, int firstCol,int endCol) {// 设置数据有效性加载在哪个单元格上,四个参数分别是：起始行、终止行、起始列、终止列CellRangeAddressList regions = new CellRangeAddressList(firstRow,endRow, firstCol, endCol);// 数据有效性对象DataValidationHelper dataValidationHelper = sheet.getDataValidationHelper();DataValidationConstraint createExplicitListConstraint = dataValidationHelper.createExplicitListConstraint(textlist);DataValidation createValidation = dataValidationHelper.createValidation(createExplicitListConstraint, regions);if (createValidation instanceof XSSFDataValidation) {createValidation.setSuppressDropDownArrow(true);createValidation.setShowErrorBox(true);} else {createValidation.setSuppressDropDownArrow(false);}sheet.addValidationData(createValidation);return sheet;}