@Override
    public Integer convertToJavaData(ReadCellData<?> cellData, ExcelContentProperty contentProperty,
                                     GlobalConfiguration globalConfiguration) throws ParseException {
        return NumberUtils.parseInteger(cellData.getStringValue(), contentProperty);
    }
Integer and string converter

@author Jiaju Zhuang
fastexcel-core/src/main/java/cn/idev/excel/converters/integer/IntegerStringConverter.java