poi导出excel-下拉列表值超过255问题

public void exportExcel(List<List<String>> list,HttpServletResponse response,String fileName) throws Exception {

    XSSFWorkbook wb = new XSSFWorkbook();
    XSSFSheet sheetCs = wb.createSheet("sheet1");
    // 为首行赋值
    for(int i=0;i<list.size();i++){XSSFRow row = sheetCs.createRow(i);
        for(int j=0;j<list.get(i).size();j++){sheetCs.setColumnWidth(j, 3500);// 设置列宽
            XSSFCell cell = row.createCell(j);
            cell.setCellValue(list.get(i).get(j));
        }
    }

    int sheetTotal=wb.getNumberOfSheets();
    XSSFRow row;
    // 第一个下拉选
    // 新建一个 sheet 页
    String hiddenSheetName = "hiddenSheet" + sheetTotal;
    XSSFSheet hiddenSheet = wb.createSheet(hiddenSheetName);
    // 数据
    String[] selectList =new String[100]; // 对应列下拉框数据
    for(int i=0;i<100;i++){selectList[i]="测试数据"+i;
    }
    // 写入下拉数据到新的 sheet 页中
    for (int i = 0; i < selectList.length; i++) {row = hiddenSheet.createRow(i);
        XSSFCell cell = row.createCell(0);
        cell.setCellValue(selectList[i]);
    }
    // 获取新 sheet 页内容
    String strFormula = hiddenSheetName + "!$A$1:$A$65535";
    XSSFDataValidationConstraint constraint = new XSSFDataValidationConstraint(DataValidationConstraint.ValidationType.LIST,strFormula);
    // 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(1,65535, 0, 0);
    // 数据有效性对象
    DataValidationHelper help = new XSSFDataValidationHelper((XSSFSheet) sheetCs);
    DataValidation validation = help.createValidation(constraint, regions);
    sheetCs.addValidationData(validation);
    // 将新建的 sheet 页隐藏掉
    wb.setSheetHidden(sheetTotal, true);
    sheetTotal++;


    // 第二个下拉选
    hiddenSheetName = "hiddenSheet" + sheetTotal;
    XSSFSheet hiddenSheet2 = wb.createSheet(hiddenSheetName);
    String[] selectList2 =new String[100]; // 对应列下拉框数据
    for(int i=0;i<100;i++){selectList2[i]="测试数据 2"+i;
    }
    for (int i = 0; i < selectList2.length; i++) {row = hiddenSheet2.createRow(i);
        XSSFCell cell = row.createCell(0);
        cell.setCellValue(selectList2[i]);
    }
    String strFormula2 = hiddenSheetName + "!$A$1:$A$65535";
    XSSFDataValidationConstraint constraint2 = new XSSFDataValidationConstraint(DataValidationConstraint.ValidationType.LIST,strFormula2);
    CellRangeAddressList regions2 = new CellRangeAddressList(1,65535, 1, 1);
    DataValidationHelper help2 = new XSSFDataValidationHelper((XSSFSheet) sheetCs);
    DataValidation validation2 = help2.createValidation(constraint2, regions2);
    sheetCs.addValidationData(validation2);
    wb.setSheetHidden(sheetTotal, true);
    sheetTotal++;


    try {OutputStream output = response.getOutputStream();
        fileName = URLEncoder.encode(fileName,"UTF-8");
        response.addHeader("Content-Disposition", "inline;filename="+fileName+".xls");
        response.setContentType("application/msexcel");
        wb.write(output);
        output.flush();
        output.close();} catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();}
    // 结束
    System.out.println("Over");

}