apache POI adding watermark in Excel workbook

Question

I\'m new to apache POI java development, I\'m trying to add watermark to excel using below code. But the watermark id overridding the contents behind it. I want to add water

Answer 1

Microsoft Excel doesn’t come with a built-in watermark feature. However, there are a couple of ways that you can simulate the look of a watermark.. But unfortunately none of those are directly supported by apache poi.

If the requirement would be XSSF only, then one could programming a picture in the header using the underlaying low level objects of XSSF.

A *.xlsx file simply is a ZIP archive. So we can unzip it and having a look at the internals. So do creating a *.xlsx file having a picture in header and then look into the *.xlsx ZIP archive.

There in /xl/worksheets/sheet1.xmlwhich is the sheets XML, we find something like:

...

 &C&G


...

So we have &G which points to a Graphic in &Center header. And we have a relation Id which points to a legacy drawing.

This legacy drawing we find in /xl/drawings/vmlDrawing1.vml. In this *.vml file also is a relation to a image in /xl/media/.

So what we must do is

1. Adding a image to the Workbook. This is actually provided by apache poi already.

2. Putting the "&G" into the center header. This also is actually provided by apache poi already.

3. Creating /xl/drawings/vmlDrawing1.vml as a PackagePart and creating a POIXMLDocumentPart which provides commit() method for saving it's XML into the package while writing out the file.

4. Creating all the needed relations.

Following code is working draft which shows the principle. As the picture I have downloaded AF101880439_en-us_draft.png from the linked Microsoft support page.

The code is complete and works and creates a result *.xlsx file having the DRAFT-picture in center header of first sheet.

import java.io.*;

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

import org.apache.poi.util.IOUtils;
import org.apache.poi.ss.util.ImageUtils;

import org.apache.poi.openxml4j.opc.*;
import org.apache.poi.POIXMLDocumentPart;

import org.apache.xmlbeans.XmlObject;

import static org.apache.poi.POIXMLTypeLoader.DEFAULT_XML_OPTIONS;

public class CreateExcelPictureInHeaderAKAWatermark {

 static void createPictureForHeader(XSSFSheet sheet, int pictureIdx, String pictureTitle, int vmlIdx, String headerPos) throws Exception {
  OPCPackage opcpackage = sheet.getWorkbook().getPackage();

  //creating /xl/drawings/vmlDrawing1.vml
  PackagePartName partname = PackagingURIHelper.createPartName("/xl/drawings/vmlDrawing" + vmlIdx+ ".vml");
  PackagePart part = opcpackage.createPart(partname, "application/vnd.openxmlformats-officedocument.vmlDrawing");
  //creating new VmlDrawing
  VmlDrawing vmldrawing = new VmlDrawing(part);

  //creating the relation to the picture in /xl/drawings/_rels/vmlDrawing1.vml.rels
  XSSFPictureData picData = sheet.getWorkbook().getAllPictures().get(pictureIdx);
  String rIdPic = vmldrawing.addRelation(null, XSSFRelation.IMAGES, picData).getRelationship().getId();

  //get image dimension
  ByteArrayInputStream is = new ByteArrayInputStream(picData.getData());
  java.awt.Dimension imageDimension = ImageUtils.getImageDimension(is, picData.getPictureType());
  is.close();

  //updating the VmlDrawing
  vmldrawing.setRIdPic(rIdPic);
  vmldrawing.setPictureTitle(pictureTitle);
  vmldrawing.setImageDimension(imageDimension);
  vmldrawing.setHeaderPos(headerPos);

  //creating the relation to /xl/drawings/vmlDrawing1.xml in /xl/worksheets/_rels/sheet1.xml.rels
  String rIdExtLink = sheet.addRelation(null, XSSFRelation.VML_DRAWINGS, vmldrawing).getRelationship().getId();

  //creating the  in /xl/worksheets/sheetN.xml
  sheet.getCTWorksheet().addNewLegacyDrawingHF().setId(rIdExtLink);

 }

 public static void main(String[] args) throws Exception {

  Workbook workbook = new XSSFWorkbook();

  Sheet sheet;
  Header header;
  InputStream is;
  byte[] bytes;

  int pictureIdx; //we need it later

  sheet = workbook.createSheet();

  header = sheet.getHeader();
  header.setCenter("&G"); // &G means Graphic

  //add picture data to this workbook
  is = new FileInputStream("AF101880439_en-us_draft.png");
  bytes = IOUtils.toByteArray(is);
  pictureIdx = workbook.addPicture(bytes, Workbook.PICTURE_TYPE_PNG);
  is.close();

  //create header picture from picture data of this workbook
  createPictureForHeader((XSSFSheet)sheet, pictureIdx, "AF101880439_en-us_draft", 1, "CH"/*CenterHeader*/);

  FileOutputStream out = new FileOutputStream("CreateExcelPictureInHeader.xlsx");
  workbook.write(out);
  out.close();
  workbook.close();    
 }

 //class for VmlDrawing
 static class VmlDrawing extends POIXMLDocumentPart {

  String rIdPic = "";
  String pictureTitle = "";
  java.awt.Dimension imageDimension = null;
  String headerPos = "";

  VmlDrawing(PackagePart part) {
   super(part);
  }

  void setRIdPic(String rIdPic) {
   this.rIdPic = rIdPic;
  }

  void setPictureTitle(String pictureTitle) {
   this.pictureTitle = pictureTitle;
  }

  void setHeaderPos(String headerPos) {
   this.headerPos = headerPos;
  }

  void setImageDimension(java.awt.Dimension imageDimension) {
   this.imageDimension = imageDimension;
  }

  @Override
  protected void commit() throws IOException {
   PackagePart part = getPackagePart();
   OutputStream out = part.getOutputStream();
   try {
    XmlObject doc = XmlObject.Factory.parse(

      ""
     +" "
     +"  "
     +" "
     +"  "
     +"  "
     +"   "
     +"   "
     +"   "
     +"   "
     +"   "
     +"   "
     +"   "
     +"   "
     +"   "
     +"   "
     +"   "
     +"   "
     +"  "
     +"  "
     +"  "
     +" "
     +"  "
     +"  "
     +" "

    );
    doc.save(out, DEFAULT_XML_OPTIONS);
    out.close();
   } catch (Exception ex) {
    ex.printStackTrace();
   }
  }

 }

}

---

Needed changings in imports to make that work using current apache poi 4.0.1:

...
//import org.apache.poi.POIXMLDocumentPart;
import org.apache.poi.ooxml.POIXMLDocumentPart;

import org.apache.xmlbeans.XmlObject;

//import static org.apache.poi.POIXMLTypeLoader.DEFAULT_XML_OPTIONS;
import static org.apache.poi.ooxml.POIXMLTypeLoader.DEFAULT_XML_OPTIONS;
...