在学习导出功能时使用 HSSFWorkbook 导出了一个 xxx.xlsx 格式的文件，然后用 XSSFWorkbook 的读取方式来拿文件去导入时出现了这个bug

这是当时做导出测试代码

Workbook wb = new HSSFWorkbook();
CreationHelper creationHelper = wb.getCreationHelper();
Sheet sheet = wb.createSheet("new sheet");
Row row = sheet.createRow(0);
Cell cell = row.createCell(0);
cell.setCellValue("dsad");
try (OutputStream fileOut = new FileOutputStream("MyExcel.xlsx")) {
   wb.write(fileOut);
然后那这个去做导入操作，因为导出的格式为.xlsx就使用OPCPackage去获取文件
OPCPackage pkg =  OPCPackage.open("MyExcel.xlsx");
XSSFWorkbook wb = new XSSFWorkbook(pkg);
Sheet newSheet = wb.getSheet("new sheet");
Row row = newSheet.getRow(0);
Cell cell = row.getCell(0);
System.out.println(cell.getStringCellValue());
pkg.close();
然后在执行导入时就报了这个错误
org.apache.poi.openxml4j.exceptions.OLE2NotOfficeXmlFileException: The supplied data appears to be in the OLE2 Format.
You are calling the part of POI that deals with OOXML (Office Open XML) Documents. You need to call a different part of POI
 to process this data (eg HSSF instead of XSSF)
HSSFWorkbook对应的是xls,XSSFWorkbook对应的是xlsx,导入导出时所使用的Workbook对象要一致。如果使用xls就都用HSSFWorkbook，使用xlsx就都用XSSFWorkbook。
// 将导出新建的 HSSFWorkbook 换成 XSSFWorkbook
Workbook wb = new XSSFWorkbook();
CreationHelper creationHelper = wb.getCreationHelper();
Sheet sheet = wb.createSheet("new sheet");
Row row = sheet.createRow(0);
Cell cell = row.createCell(0);
cell.setCellValue("dsad");
try (OutputStream fileOut = new FileOutputStream("MyExcel.xlsx")) {
   wb.write(fileOut);