You can use PDFBox's PDFTextStripperByArea class to extract text from a specific region of a document. You can build on this by identifying the region each cell of the table. This isn't provided out of the box, but the example DrawPrintTextLocations class demonstrates how you can parse the bounding boxes of individual characters in a document (it would be great to parse bounding boxes of strings or paragraphs, but I haven't seen support in PDFBox for this - see this question). You can use this approach to group up all touching bounding boxes to identify distinct cells of a table. One way to do this is to maintain a set boxes of Rectangle2D regions and then for each parsed character find the character's bounding box as in DrawPrintTextLocations.writeString(String string, List<TextPosition> textPositions) and merge it with the existing contents.
Rectangle2D bounds = s.getBounds2D();
// Pad sides to detect almost touching boxes
Rectangle2D hitbox = bounds.getBounds2D();
final double dx = 1.0; // This value works for me, feel free to tweak (or add setter)
final double dy = 0.000; // Rows of text tend to overlap, so no need to extend
hitbox.add(bounds.getMinX() - dx , bounds.getMinY() - dy);
hitbox.add(bounds.getMaxX() + dx , bounds.getMaxY() + dy);
// Find all overlapping boxes
List<Rectangle2D> intersectList = new ArrayList<Rectangle2D>();
for(Rectangle2D box: boxes) {
if(box.intersects(hitbox)) {
intersectList.add(box);
}
}
// Combine all touching boxes and update
for(Rectangle2D box: intersectList) {
bounds.add(box);
boxes.remove(box);
}
boxes.add(bounds);
You can then pass these regions to PDFTextStripperByArea.
You can also go one further and separate out the horizontal and vertical components of these regions, and so infer regions of all the table's cells, regardless of whether then hold any content.
I have had cause to perform these steps, and eventually wrote my own PDFTableStripper class using PDFBox. I've shared my code as a gist on GitHub. The main method gives an example of how the class can be used:
try (PDDocument document = PDDocument.load(new File(args[0])))
{
final double res = 72; // PDF units are at 72 DPI
PDFTableStripper stripper = new PDFTableStripper();
stripper.setSortByPosition(true);
// Choose a region in which to extract a table (here a 6"wide, 9" high rectangle offset 1" from top left of page)
stripper.setRegion(new Rectangle(
(int) Math.round(1.0*res),
(int) Math.round(1*res),
(int) Math.round(6*res),
(int) Math.round(9.0*res)));
// Repeat for each page of PDF
for (int page = 0; page < document.getNumberOfPages(); ++page)
{
System.out.println("Page " + page);
PDPage pdPage = document.getPage(page);
stripper.extractTable(pdPage);
for(int c=0; c<stripper.getColumns(); ++c) {
System.out.println("Column " + c);
for(int r=0; r<stripper.getRows(); ++r) {
System.out.println("Row " + r);
System.out.println(stripper.getText(r, c));
}
}
}
}