Accessing PDF Bookmarks

See package:org.apache.pdfbox.pdmodel.interactive.documentnavigation.outline
See example:PrintBookmarks

A PDF can contain an outline of a document and jump to pages within a PDF document. An outline is a hierarchical tree structure of nodes that point to pages.

To access the root of the outline you go through the PDDocumentOutline 

      PDDocument doc = PDDocument.load( ... );
      PDDocumentOutline root = doc.getDocumentCatalog().getDocumentOutline();

Now you can traverse the tree using the getFirstChild() and getNextSibling() functions. 

      PDOutlineItem item = root.getFirstChild();
      while( item != null )
      {
          System.out.println( "Item:" + item.getTitle() );
          PDOutlineItem child = item.getFirstChild();
          while( child != null )
          {
              System.out.println( "    Child:" + child.getTitle() );
              child = child.getNextSibling();
          }
          item = item.getNextSibling();
      }

Creating Bookmarks

See example:CreateBookmarks

Creating bookmarks is just as easy. You first need to create the PDDocumentOutline and then add some PDOutlineItem objects to it. 

      //first create the document outline and add it to the page
      PDDocumentOutline outline = new PDDocumentOutline();
      doc.getDocumentCatalog().setDocumentOutline( outline );

      //Create a root element to show in the tree
      PDOutlineItem root = new PDOutlineItem();
      root.setTitle( "Root of Document" );
      outline.appendChild( root)

      //Get the page to refer to
      PDPage firstPage = (PDPage)doc.getAllPages().get( 0 );

      //Create the outline item to refer to the first page.
      PDOutlineItem firstPageItem = new PDOutlineItem();
      firstPageItem.setTitle( "First Page of document" );
      firstPageItem.setDestination( firstPage );
      root.appendChild( firstPageItem );

NOTE: By default all nodes in the outline tree are closed. You need to call openNode() if you want the node to be open when the document is opened.