Can't read Excel 2010 file with Apache POI. Fi

问题:

I am trying the this testfile with the Apache POI API (current version 3-10-FINAL). The following test code

import java.io.FileInputStream;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExcelTest {

    public static void main(String[] args) throws Exception {
        String filename = "testfile.xlsx";
        XSSFWorkbook wb = new XSSFWorkbook(new FileInputStream(filename));
        XSSFSheet sheet = wb.getSheetAt(0);
        System.out.println(sheet.getFirstRowNum());
    }
}

results in the first row number to be -1 (and existing rows come back as null). The test file was created by Excel 2010 (I have no control over that part) and can be read with Excel without warnings or problems. If I open and save the file with my version of Excel (2013) it can be read perfectly as expected.

Any hints into why I can't read the original file or how I can is highly appreciated.

回答1:

The testfile.xlsx is created with "SpreadsheetGear 7.1.1.120". Open the XLSX file with a software which can deal with ZIP archives and look into /xl/workbook.xml to see that. In the worksheets/sheet?.xml files is to notice that all row elements are without row numbers. If I put a row number in the first row-tag like <row r="1"> then apache POI can read this row.

If it comes to the question, who is to blame for this, then the answer is definitely both Apache Poi and SpreadsheetGear ;-). Apache POI because the attribute r in the row element is optional. But SpreadsheetGear also because there is no reason not to use the r attribute if Excel itself does it ever.

If you cannot get the testfile.xlsx in a format which can Apache POI read directly, then you must work with the underlying objects. The following works with your testfile.xlsx:

import org.apache.poi.xssf.usermodel.*;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.*;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.FileInputStream;
import java.io.InputStream;

import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTWorksheet;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTSheetData;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTRow;

import java.util.List;

class Testfile {

 public static void main(String[] args) {
  try {

   InputStream inp = new FileInputStream("testfile.xlsx");
   Workbook wb = WorkbookFactory.create(inp);

   Sheet sheet = wb.getSheetAt(0);

   System.out.println(sheet.getFirstRowNum());

   CTWorksheet ctWorksheet = ((XSSFSheet)sheet).getCTWorksheet();

   CTSheetData ctSheetData = ctWorksheet.getSheetData();

   List<CTRow> ctRowList = ctSheetData.getRowList();

   Row row = null;
   Cell[] cell = new Cell[2];

   for (CTRow ctRow : ctRowList) {
    row = new MyRow(ctRow, (XSSFSheet)sheet);
    cell[0] = row.getCell(0);
    cell[1] = row.getCell(1);
    if (cell[0] != null && cell[1] != null && cell[0].toString() != "" && cell[1].toString() != "") 
       System.out.println(cell[0].toString()+"\t"+cell[1].toString());
   }

  } catch (InvalidFormatException ifex) {
  } catch (FileNotFoundException fnfex) {
  } catch (IOException ioex) {
  }
 }
}

class MyRow extends XSSFRow {
 MyRow(org.openxmlformats.schemas.spreadsheetml.x2006.main.CTRow row, XSSFSheet sheet) {
  super(row, sheet);
 }
}

I have used org.openxmlformats.schemas.spreadsheetml.x2006.main.CTWorksheet, org.openxmlformats.schemas.spreadsheetml.x2006.main.CTSheetData, org.openxmlformats.schemas.spreadsheetml.x2006.main.CTRow. Which are part of the Apache POI Binary Distribution poi-bin-3.10.1-20140818 and there are within poi-ooxml-schemas-3.10.1-20140818.jar

For a documentation see http://grepcode.com/snapshot/repo1.maven.org/maven2/org.apache.poi/ooxml-schemas/1.1/

And I have extend XSSFRow, because we can't use the XSSFRow constructor directly since it has protected access.