poi解析Excel文件时有两种格式： 

HSSFWorkbook格式用来解析Excel2003（xls）的文件 

XSSFWorkbook格式用来解析Excel2007（xlsx）的文件 

如果用HSSFWorkbook解析Excel2007（xlsx）时就会报异常：“The supplied data appears to be in the Office 2007+ XML. You are calling the part of POI that deals with OLE2 Office Documents. You need to call a different part of POI to process this data (eg XSSF instead of HSSF)”

因为HSSFWorkbook和XSSFWorkbook都实现了Workbook接口，所以我们可以用Workbook来解析两个版本的Excel。 

代码如下：

1 try{ 2     //将文件的输入流转换成Workbook 3     Workbook wb = WorkbookFactory.create(numFile.getInputStream()); 4     //获得第一个工作表 5     Sheet sheet = wb.getSheetAt(0); 6     //获得第一行 7     Row row = sheet.getRow(0); 8     //获得第一行的第一列 9     Cell cell = row.getCell(0);10 }catch (Exception e){11     e.printStackTrace();12 }