How to make verticaltext cellstyle with Apache POI

Recently, I met a question: I need to export an excel(xlsx) with java, which must contain this kind of cell style:

I made a excel file with this vertical text, and exported as a xml file. Then I found that the style has an attribute named 'VerticalText':

By experience, I chose Apache POI. But I couldn't find any way to generate the cell style with POI. I could only find rotate method, which could't meet the requirement.

So I read more code of POI, and found that the cellstyles are build from some xsb file, which do not contain vertical text either.

Any help much appreciated.

The XML in your picture is Excel 2003 SpreadsheetML. But an *.xlsx file is a ZIP archive containing Office Open XML files. In that ZIP archive the styles.xml contains:

...
<cellXfs count="2">
 ...
 <xf numFmtId="0" fontId="0" fillId="0" borderId="0" xfId="0">
  <alignment textRotation="255"/>
 </xf>
</cellXfs>
...

There <alignment textRotation="255"/> is for vertical text.

This can be set using apache poi like so:

import java.io.FileOutputStream;

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;


public class CreateXSSFVerticalText {

 public static void main(String[] args) throws Exception {
  Workbook workbook = new XSSFWorkbook();

  CellStyle cellStyle = workbook.createCellStyle();
  cellStyle.setRotation((short)255);

  Sheet sheet = workbook.createSheet();
  Row row = sheet.createRow(0);
  Cell cell = row.createCell(0);
  cell.setCellValue("test");
  cell.setCellStyle(cellStyle);


  FileOutputStream fileOut = new FileOutputStream("CreateXSSFVerticalText.xlsx");
  workbook.write(fileOut);
  fileOut.close();
  workbook.close();
 }
}

Since the Office Open XML formats (like *.xlsx) are ZIP archives containing XML files it is pretty easy to determine the necessary XML attributes. Simply create a simple *.xlsx file having the needed formatting using the Excel GUI. Then unzip the *.xlsx file and have a look at xl/styles.xml.