Java poi 读取excel流

不依赖模型.
获取的结果按列存储,有类型和长度,方便拼接自定义sql

   /**
     * poi读取excel流(2G内存环境下,大于5M有OOM风险)
     *
     * @param is       输入流
     * @param filename 文件名称
     * @return 返回表格数据
     * @Describe 从输入流读取文件, 解析内容
     */
    public static List readExcelBean(InputStream is, String filename) {
        List excel = Lists.newArrayList();
//        ByteArrayOutputStream baos = null;
        try {
//            baos = getOutputStream(is);
//            is = new ByteArrayInputStream(baos.toByteArray());
            Workbook workbook;
            // 根据不同类型初始化
            if (filename.endsWith(xls)) {
                workbook = new HSSFWorkbook(is);
            } else if (filename.endsWith(xlsx)) {
                workbook = new XSSFWorkbook(is);
            } else {
                throw new IOException("读取失败");
            }
            // 遍历sheet
            for (int i = 0; i < workbook.getNumberOfSheets(); i++) {
                Sheet sheetAt = workbook.getSheetAt(i);
                ExcelSheetBean _sheet = new ExcelSheetBean();
                _sheet.setTableName(filename);
                _sheet.setSheetName(sheetAt.getSheetName());
                List colValues = Lists.newLinkedList();
                int physicalNumberOfRows = sheetAt.getPhysicalNumberOfRows();
                // 遍历所有行
                for (int j = 0; j < physicalNumberOfRows; j++) {
                    Row row = sheetAt.getRow(j);
                    if (row == null) {
                        continue;
                    }
                    // 第一行不做类型判断,初始化list大小
                    if (j == 0) {
                        int physicalNumberOfCells = row.getPhysicalNumberOfCells();
                        for (int k = 0; k < physicalNumberOfCells; k++) {
                            Cell cell = row.getCell(k);
                            ExcelColBean excelColBean = new ExcelColBean();
                            excelColBean.getColValues().add(cell.toString());
                            colValues.add(excelColBean);
                        }
                        continue;
                    }
                    // 遍历单元格
                    for (int k = 0; k < colValues.size(); k++) {
                        // 设置列类型
                        Cell cell = row.getCell(k);
                        if (cell == null || StringUtil.isEmpty(cell.toString()) || cell.getCellTypeEnum() == BLANK) {
                            colValues.get(k).getColValues().add("");
                            continue;
                        } else if (colValues.get(k).getType() == null) {
                            colValues.get(k).setType(getCellType(cell));
                        } else if (colValues.get(k).getType() != ExcelCellType.STRING && getCellType(cell) != colValues.get(k).getType()) {
                            colValues.get(k).setType(ExcelCellType.STRING);
                        }

                        // 根据类型赋值
                        switch (getCellType(cell)) {
                            case NUMBER:
                                Double value;
                                try {
                                    value = cell.getNumericCellValue();
                                } catch (Exception e) {
                                    value = Double.valueOf(cell.getStringCellValue());
                                }
                                boolean isInt = false;
                                if (Math.round(value) == value) {
                                    isInt = true;
                                }
                                // BigDecimal处理精度问题
                                if (isInt && value < Long.MAX_VALUE) {
                                    colValues.get(k).getColValues().add(new BigDecimal(value.toString()).toPlainString());
                                    Integer len = Long.valueOf(Math.round(value)).toString().length();
                                    if (colValues.get(k).getType() == ExcelCellType.NUMBER
                                            && len > colValues.get(k).getPreQuantity()) {
                                        colValues.get(k).setPreQuantity(len);
                                    }
                                } else {
                                    colValues.get(k).getColValues().add(new BigDecimal(cell.toString()).toPlainString());
                                    if (colValues.get(k).getType() == ExcelCellType.NUMBER) {
                                        String[] split = new BigDecimal(cell.toString()).toPlainString().split("\\.");
                                        if (split[0].length() > colValues.get(k).getPreQuantity()) {
                                            colValues.get(k).setPreQuantity(split[0].length());
                                        }
                                        if (!isInt && split.length > 1 && split[1].length() > colValues.get(k).getSufQuantity()) {
                                            colValues.get(k).setSufQuantity(split[1].length());
                                        }
                                    }
                                }
                                break;
                            case STRING:
                                if (cell.toString().contains(("'"))) {
                                    colValues.get(k).getColValues().add(cell.toString().replace("'", "\\'"));
                                } else {
                                    colValues.get(k).getColValues().add(cell.toString());
                                }
                                if (cell.toString().length() > colValues.get(k).getStrQuantity()) {
                                    colValues.get(k).setStrQuantity(cell.toString().length());
                                }
                                break;
                            case DATE:
                                SimpleDateFormat sdf = new SimpleDateFormat(DEFAULTDATAFORMAT);
                                try {
                                    colValues.get(k).getColValues().add(sdf.format(getJavaDate(cell.getNumericCellValue())));
                                } catch (IllegalStateException e) {
                                    colValues.get(k).getColValues().add(sdf.format(getDate(cell.toString())));
                                }

                                break;
                        }
                    }
                }
                _sheet.setCols(colValues);
                excel.add(_sheet);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
//          closeInputStream(baos);
        }
        return excel;
    }

下面是自定义类:

/**
 * excel 表
 */
@Data
@NoArgsConstructor
public static class ExcelSheetBean {

    private String tableName;

    private String sheetName;

    private List cols = Lists.newArrayList();

}

    /**
     * excel 列
     */
    @Data
    @NoArgsConstructor
    public static class ExcelColBean {

        // 类型
        private ExcelCellType type;

        // 整数最大位数
        private Integer preQuantity = 0;

        // 小数最大位数
        private Integer sufQuantity = 0;

        // 字符最大值
        private Integer strQuantity = 255;

        // 值集
        private List