java通过poi导出excel

excel模板类

/**
 * Created by wang on 2018/9/11.
 */
public class ScoreCertExcelUtil {
    /**
     * 打印表格
     */
    public static HSSFWorkbook print(List<Map<String, Object>> resultList) throws Exception {
        //通用变量
        int rowNo = 0, cellNo = 0;
        Row nRow;
        Cell nCell;

        //1.创建工作簿
        HSSFWorkbook wb = new HSSFWorkbook();
        //2.创建工作表
        Sheet sheet = wb.createSheet();
        //设置列宽
        sheet.setColumnWidth(cellNo, 29 * 256);

        cellNo = 0;//重置
        //3.创建行对象
        //=======================================小标题====================================
        String titles[] =
                {"编号"};

        //创建小标题的行对象
        nRow = sheet.createRow(rowNo++);
        nRow.setHeightInPoints(26.25f);//设置行高

        //创建单元格对象，并设置内容 ，并设置样式
        CellStyle titleCellStyle = title(wb);
        for (String title : titles) {
            nCell = nRow.createCell(cellNo++);//创建单元格对象
            nCell.setCellValue(title);//设置内容
            nCell.setCellStyle(titleCellStyle);//设置样式
        }

        //=======================================数据输出=================================
        CellStyle textCellStyle = text(wb);
        for (int i = 0; i < resultList.size(); i++) {

            nRow = sheet.createRow(rowNo++);//产生数据行
            nRow.setHeightInPoints(24);//设置行高

            cellNo = 0;

            nCell = nRow.createCell(cellNo);
            nCell.setCellValue((String) resultList.get(i).get("scoreCertCode"));
            nCell.setCellStyle(textCellStyle);

        }

        return wb;
    }

    //小标题的样式
    private static CellStyle title(Workbook wb) {
        CellStyle style = wb.createCellStyle();
        Font font = wb.createFont();
        font.setFontName("黑体");
        font.setFontHeightInPoints((short) 12);
        font.setBold(true);

        style.setFont(font);
        style.setAlignment(HorizontalAlignment.CENTER);
        style.setVerticalAlignment(VerticalAlignment.CENTER);
        style.setBorderTop(BorderStyle.THIN);
        style.setBorderBottom(BorderStyle.THIN);
        style.setBorderLeft(BorderStyle.THIN);
        style.setBorderRight(BorderStyle.THIN);

        //背景色
        style.setFillPattern(FillPatternType.SOLID_FOREGROUND);
        style.setFillForegroundColor(HSSFColor.HSSFColorPredefined.YELLOW.getIndex());
        return style;
    }

    //文字样式
    private static CellStyle text(Workbook wb) {
        CellStyle style = wb.createCellStyle();
        Font font = wb.createFont();
        font.setFontName("Times New Roman");
        font.setFontHeightInPoints((short) 10);

        style.setFont(font);
        style.setAlignment(HorizontalAlignment.CENTER);
        style.setVerticalAlignment(VerticalAlignment.CENTER);
        style.setBorderTop(BorderStyle.THIN);
        style.setBorderBottom(BorderStyle.THIN);
        style.setBorderLeft(BorderStyle.THIN);
        style.setBorderRight(BorderStyle.THIN);

        return style;
    }
}

serviceImpl层代码块（service层这里就不写了）

@Override
public ResultDO<List<Map<String, Object>>> downloadExcel() {
    List<Map<String, Object>> resultList = new ArrayList<>();
    Map<String, Object> rMap;
    for (int i=0;i<10;i++) {
        rMap = new HashMap<>();
        rMap.put("scoreCertCode",i);
        resultList.add(rMap);
    }
    return new ResultDO<>(resultList);
}

controller层代码

/**
 * 导出表格
 */
@ResponseBody
@RequestMapping("/downloadExcel.ajax")
public Map<String, Object> downloadExcel(HttpServletResponse response) {
    Map<String, Object> resultMap = new HashMap<>();
    String fileName ="111.xls";
    response.setContentType("application/vnd.ms-excel");
    response.setHeader("Content-disposition", "attachment; filename=" + fileName);
    OutputStream outputStream;
    ResultDO<List<Map<String, Object>>> workbookResultDO = certBindLogService.downloadExcel();

    if (workbookResultDO.success()) {
        try {
            List<Map<String, Object>> resultList = workbookResultDO.getObj();
            HSSFWorkbook wb = null;
            try {
                wb = DownloadExcelUtil.print(resultList);
            } catch (Exception e) {
                MedChatLogger.error(e);
            }
            outputStream = response.getOutputStream();
            wb.write(outputStream);
            outputStream.flush();
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        resultMap.put(MESSAGE, "导出成功");
        this.setSuccess(resultMap);
    } else {
        this.setFailure(resultMap, workbookResultDO.getErrorMsg());
    }

    return resultMap;
}

之前写的时候样式没有提到外面  每次表格样式赋值的时候都要调用一次样式的方法，

数据量大的时候就会报这个错（The maximum number of cell styles was exceeded. You can define up to 4000 styles）

同事帮找到的解决方案的例子，这里把解决方案地址附上（https://blog.csdn.net/johnstrive/article/details/8568113）

我这写的例子是一列数据的例子，如果需要多列可以在ScoreCertExcelUtil里的小标题和数据输出位置追加列和行，代码可能不够优化，欢迎指点，共同交流。