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Home » Newsletter » August 2007

By Suryanarayan P

PDFOne Java makes it very easy to merge and split PDF documents. In this article, you will learn to perform these tasks.

Merging PDF Documents

Merging PDF documents can be performed using the merge() method of the PDFDocument class. This method takes an array list parameter containing pathnames of the files that need to be merged.

To illustrate this, I created a new PDF document “MergedDocument.pdf” by merging three PDF documents of different sizes namely “Envelope.pdf”, “ResellerLetter.pdf” and “ResellerForm.pdf”.

import java.util.ArrayList;
import java.io.IOException;

import com.gnostice.pdfone.PDFOne;
import com.gnostice.pdfone.PdfDocument;
import com.gnostice.pdfone.PdfException;
import com.gnostice.pdfone.PdfPageLayout;
import com.gnostice.pdfone.PdfWriter;

public class MergeDocuments
{
 static
 {
  PDFOne.activate(
     "T95VZE:W8HBPVA:74VQ8QV:LO4V8",
     "9B1HRZAP:X5853ERNE:5EREMEGRQ:TX1R10");
 }

 public static void main(String[] args) throws IOException,
   PdfException
 {
  /* Prepare a list of documents that need to be merged */
  ArrayList al = new ArrayList();
  al.add("Envelope.pdf");
  al.add("ResellerLetter.pdf");
  al.add("ResellerForm.pdf");

  /* Create a PdfWriter instance for output PDF file */
  PdfWriter w = PdfWriter.fileWriter("MergedDocument.pdf");

  /* 
   Create a PdfDocument instance with 
   the PdfWriter instance 
  */
  PdfDocument d = new PdfDocument(w);

  /* Merge documents in the list */
  d.merge(al);

  /* Set output file to be opened after it is written */
  d.setOpenAfterSave(true);

  /* Write the document object to file */
  d.write();

  /*  
   Close all I/O streams associated 
   with this writer object 
  */
  w.dispose();
 }
}

And, here is the result.

Splitting PDF Documents

PDFOne Java offers two ways of splitting PDF files:

• Extract a selection of pages from the original document and store it in a single output PDF document - using extractPagesTo() method of PDFDocument class.
• Divide the pages in the original document based on a number and store them in several output PDF documents - using split() method of PDFDocument class.

import com.gnostice.pdfone.PdfDocument;
import com.gnostice.pdfone.PdfException;
import com.gnostice.pdfone.PdfNeedFileNameHandler;
import com.gnostice.pdfone.PdfReader;

public class SplitDocuments
             implements PdfNeedFileNameHandler
{
 static int fileNoCount = 1;

 static
 {
   PDFOne.activate("T95VZE:W8HBPVA:74VQ8QV:LO4V8",
      "9B1HRZAP:X5853ERNE:5EREMEGRQ:TX1R10");
 }

 /*
  Specify an event handler that will provide output filenames
 */
 public void onNeedFileName(PdfDocument d, 
                            StringBuffer fileName)
 {
   fileName.delete(0, fileName.length());
   fileName.append("Split_File_" + (fileNoCount++) + ".pdf");
 }

 public static void main(String[] args)
    throws IOException,
    PdfException
 {
   /* Create a PdfReader instance for the PDF file */
   PdfReader r = PdfReader.fileReader("DocumentToSplit.pdf");

   /*
    Create a PdfDocument instance with
    the PdfReader instance
   */
   PdfDocument d = new PdfDocument(r);

   /* Extract pages 1, 2, & 4 */
   d.extractPagesTo("ExtractedPages.pdf", "1-2,4");

   /*
    Specify class that implements the PdfNeedFileNameHandler 
    interface, whose onNeedFileName() method will be called 
    by the split() method below to obtain output filenames
   */
   d.setOnNeedFileName(new SplitDocuments());

   /*
    Call the split method, which splits document, calls 
    interface method specified by setOnNeedFileName(), 
    obtains file names, and saves output files
   */
   d.split(1);

   /*
    Close all I/O streams associated
    with the reader object
   */
   r.dispose();
 }
}

The extractPagesTo() method takes the pathname of an output file and a page range as arguments. It extracts all pages in the specified page range and saves them to the specified output file.

The split() method takes a number as argument. It begins extracting consecutive pages totaling that number into new PDF documents until all pages in the original document are exhausted. The names of the new documents are provided by the onNeedFileName method of the PdfNeedFileNameHandler interface implemented by the class calling the split() method.