Poi生成Excel———实体类中含Map集合的情况

/**
     * 生成xls文件
     *
     * @param updateDscVOS
     * @return 生成的文件路径
     */
    public String getXlsFile(List<UpdateDscVO> updateDscVOS) {
        String exportPath = null;
        FileOutputStream fileOut = null;
        try {

            HSSFWorkbook wb = new HSSFWorkbook();
            HSSFFont font = wb.createFont();
            //编辑字体
            font.setFontHeightInPoints((short) 15);
            font.setBold(true);
            //设置字体大小与加粗与居中
            HSSFCellStyle cellStyle = wb.createCellStyle();
            //设置居中
            HSSFCellStyle cellStyle2 = wb.createCellStyle();
            //设置换行与居中
            HSSFCellStyle cellStyle3 = wb.createCellStyle();
            //设置字体
            cellStyle.setFont(font);
            cellStyle.setAlignment(HorizontalAlignment.CENTER);

            cellStyle2.setAlignment(HorizontalAlignment.CENTER);
            //设置换行
            cellStyle3.setWrapText(true);
            cellStyle3.setAlignment(HorizontalAlignment.CENTER);

            String fileName = new SimpleDateFormat("yyyyMMddhhMMss").format(new Date()) + "dsc.xls";
            HSSFSheet sheet = wb.createSheet(fileName);
            sheet.autoSizeColumn(0);
            sheet.setDefaultColumnWidth(20);

            //初始化表格------------------
            Class<? extends UpdateDscVO> aClass = updateDscVOS.get(0).getClass();
            Field[] fields = aClass.getDeclaredFields();
            //创建表头
            HSSFRow row = sheet.createRow(0);
            HSSFRow row2 = sheet.createRow(1);
            int j = 0;
            for (Field field : fields) {
                if (j == 0) {
                    HSSFCell cell = row.createCell(j);
                    cell.setCellValue("序号");
                    cell.setCellStyle(cellStyle);
                    sheet.addMergedRegion(new CellRangeAddress(
                            0, //first row (0-based)
                            1, //last row  (0-based)
                            j, //first column (0-based)
                            j  //last column  (0-based)
                    ));
                    j++;
                }
                if (Optional.ofNullable(field.getAnnotation(XlsPropertie.class)).isPresent()) {
                    XlsPropertie xlsPropertie = field.getDeclaredAnnotation(XlsPropertie.class);
                    HSSFCell cell = row.createCell(j);
                    cell.setCellValue(xlsPropertie.name());
                    cell.setCellStyle(cellStyle);
                    /**表格合并 第0行与第1行  j表示列 相同表示不合并*/
                    sheet.addMergedRegion(new CellRangeAddress(
                            0, //first row (0-based)
                            1, //last row  (0-based)
                            j, //first column (0-based)
                            j  //last column  (0-based)
                    ));
                    j++;
                }
                if (Optional.ofNullable(field.getAnnotation(XlsMapPropertie.class)).isPresent()) {
                    XlsMapPropertie xlsMapPropertie = field.getAnnotation(XlsMapPropertie.class);
                    String name = xlsMapPropertie.name();
                    HSSFCell cell = row.createCell(j);
                    cell.setCellValue(name);
                    cell.setCellStyle(cellStyle);
                    String[] strings = xlsMapPropertie.boundFactor();
                    int length = strings.length;
                    //对每个单元格操作  map集合需要拆解  在此处不合并 可根据需求定义*/
                    sheet.addMergedRegion(new CellRangeAddress(
                            0, //first row (0-based)
                            0, //last row  (0-based)
                            j, //first column (0-based)
                            j + length - 1  //last column  (0-based)
                    ));
                    for (String string : strings) {
                        HSSFCell cell1 = row2.createCell(j);
                        cell1.setCellStyle(cellStyle);
                        cell1.setCellValue(string);
                        j++;
                    }
                }
            }
            //初始化结束---------------------------------
            int l = 2;
            int index = 0;
            int downIndex = 1;
            for (UpdateDscVO updateDscVO : updateDscVOS) {
                HSSFRow rowNext = sheet.createRow(l);
                HSSFCell cell = rowNext.createCell(index);
                if (index == 0) {
                    cell.setCellValue(downIndex);
                    cell.setCellStyle(cellStyle2);
                    downIndex++;
                    index++;
                }

                cell = rowNext.createCell(index);
                cell.setCellValue(updateDscVO.get***());
                cell.setCellStyle(cellStyle2);
                index++;

                cell = rowNext.createCell(index);
                cell.setCellValue(new SimpleDateFormat("yyyy:MM:dd hh:MM:ss").format(updateDscVO.get***()));
                cell.setCellStyle(cellStyle2);
                index++;

                cell = rowNext.createCell(index);
                cell.setCellValue(updateDscVO.get***());
                cell.setCellStyle(cellStyle2);
                index++;

                cell = rowNext.createCell(index);
                cell.setCellValue(updateDscVO.get***());
                cell.setCellStyle(cellStyle3);
                index++;

                cell = rowNext.createCell(index);
                cell.setCellValue(updateDscVO.get***());
                cell.setCellStyle(cellStyle3);
                index++;

                cell = rowNext.createCell(index);
                cell.setCellValue(updateDscVO.get***());
                cell.setCellStyle(cellStyle2);
                index++;

                Set<Map.Entry<String, String>> entries = updateDscVO.getUpdateCore().entrySet();
                //没列的下标  递增与恢复设置列
                int temp = index;
                //录入更新内容与要素名
                for (Map.Entry<String, String> entry : entries) {
                    index = temp;
                    /**Map对象需要自行加入List对应的key值*/
                    for (String s : layerNameList()) {
                        if (s.equals(entry.getKey())) {
                            cell = rowNext.createCell(index);
                            cell.setCellValue(updateDscVO.getUpdateCore().get(entry.getKey()));
                            cell.setCellStyle(cellStyle3);
                        }
                        index++;
                    }
                }

                Set<Map.Entry<String, Integer>> entries1 = updateDscVO.getUpdateDetailNum().entrySet();
                temp = index;
                //录入统计量与要素名
                for (Map.Entry<String, Integer> entry : entries1) {
                    index = temp;
                    for (String s : layerNameList()) {
                        if (s.equals(entry.getKey())) {
                            cell = rowNext.createCell(index);
                            cell.setCellValue(updateDscVO.getUpdateDetailNum().get(entry.getKey()));
                            cell.setCellStyle(cellStyle3);
                        }
                        index++;
                    }
                }
                index = 0;
                l++;
            }
            exportPath = path + File.separator + fileName;
            fileOut = new FileOutputStream(exportPath);
            wb.write(fileOut);
            fileOut.flush();
            fileOut.close();
        } catch (IOException e) {
            throw new CommonException("文件生成失败");
        } finally {
            if (fileOut != null) {
                try {
                    fileOut.close();
                } catch (IOException e) {
                    log.info("关闭成功");
                }
            }
        }
        return exportPath;
    }
/**传入Map对象的key部分值*/
public static List<String> layerNameList() {
        List<String> layerNameList = new ArrayList<>();
        layerNameList.add("***");
        layerNameList.add("***");
        layerNameList.add("***");
        layerNameList.add("***");
        layerNameList.add("***");
        layerNameList.add("***");
        layerNameList.add("***");
        layerNameList.add("***");
        layerNameList.add("***");
        layerNameList.add("***");
        layerNameList.add("***");
        return layerNameList;
    }

实体类：

public class UpdateDscVO implements Serializable {
    private static final long serialVersionUID = 576879208023109952L;
    
    private String field0;
    
    @XlsPropertie(name = "**")
    private String field1;
    
    @XlsPropertie(name = "***")
    private Date field2;
    
    @XlsPropertie(name = "***")
    private String field3;
    
    @XlsPropertie(name = "***")
    private String field4;
    
    @XlsPropertie(name = "***")
    private String field5;
    
    @XlsPropertie(name = "***")
    private String field6;
    
    private String field7;
    
    @XlsMapPropertie(name = "第一行",boundFactor = {"各列名1","各列名2","各列名3","各列名4"})
    private Map<String,String> field8;
    
   @XlsMapPropertie(name = "第一行",boundFactor = {"各列名1","各列名2","各列名3","各列名4"})
    private Map<String,Integer> field9;
}

注解：

/**
 * @author secondj
 * @Date 2022/3/16 8:46
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface XlsPropertie {
    String name() default "";
}

效果图：

适合有Map集合的VO对象使用，其他情况建议使用开源框架——EazyExcel 

后续可把对象优化为根据反射获取属性对应的get方法。