Problem in merging large collection of PDF in single pdf at a time-itext

Question

hi
i am using itext library for PDF generation.My problem is ,when i merge the large number of PDFs which is already
generated, in a single PDF ,i got 'Out of Memery' exceptions,but when i doing this with limited number of PDFs
they are concated as a single PDF .so what shall i do to overcome Out of memory exceptions.because,our client wants to print the mass PDF ,which may have more than 1000 PDFs on a single merged PDF .if any possible,when i merge the single PDF with already merged PDF one by one at a time when it will be generated,how can i handle I/O streams to open one PDF at a time and merge with already generated PDF on the same time,and how can i append the generating PDF directly on already generated PDF using streams
This is my java code:
package javaexamples;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import com.lowagie.text.Document;
import com.lowagie.text.pdf.BaseFont;
import com.lowagie.text.pdf.PdfContentByte;
import com.lowagie.text.pdf.PdfImportedPage;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfWriter;
public class ConcatPDFs {
          public static void main(String[] args) {
          try {
          List pdfs = new ArrayList();
          Document document     = new Document();
          OutputStream output = new FileOutputStream("E:\\templates\\out\\Merged PDF\\merge.pdf",true);
          PdfWriter writer      = PdfWriter.getInstance(document, output);
          pdfs.add(new FileInputStream("E:\\templates\\out\\07J439HF_FINAL_EVALU.pdf"));
          pdfs.add(new FileInputStream("E:\\templates\\out\\07J440HF_FINAL_EVALU.pdf"))*;*//it may be increased over thousand paths.
          ConcatPDFs.concatPDFs(document,writer,pdfs, true);
          output.flush();
          document.close();
          output.close();
          } catch (Exception e) {
          e.printStackTrace();
          public static void concatPDFs(Document document,PdfWriter writer,List streamOfPDFFiles, boolean paginate) {
          try {
          List pdfs = streamOfPDFFiles;
          List readers = new ArrayList();
          int totalPages = 0;
          java.util.Iterator iteratorPDFs = pdfs.iterator();
          // Create Readers for the pdfs.
          while (iteratorPDFs.hasNext()) {
          InputStream pdf = (FileInputStream)iteratorPDFs.next();
          PdfReader pdfReader = new PdfReader(pdf);
          readers.add(pdfReader);
          totalPages += pdfReader.getNumberOfPages();
          // Create a writer for the outputstream
          document.open();
          BaseFont bf = BaseFont.createFont(BaseFont.HELVETICA, BaseFont.CP1252, BaseFont.NOT_EMBEDDED);
          PdfContentByte cb = writer.getDirectContent(); // Holds the PDF
          // data
          PdfImportedPage page;
          int currentPageNumber = 0;
          int pageOfCurrentReaderPDF = 0;
          Iterator iteratorPDFReader = readers.iterator();
          // Loop through the PDF files and add to the output.
          while (iteratorPDFReader.hasNext()) {
          PdfReader pdfReader = (PdfReader)iteratorPDFReader.next();
          // Create a new page in the target for each source page.
          while (pageOfCurrentReaderPDF < pdfReader.getNumberOfPages()) {
          document.newPage();
          pageOfCurrentReaderPDF++;
          currentPageNumber++;
          page = writer.getImportedPage(pdfReader, pageOfCurrentReaderPDF);
          cb.addTemplate(page, 0, 0);
          // Code for pagination.
          if (paginate) {
          cb.beginText();
          cb.setFontAndSize(bf, 9);
          cb.showTextAligned(PdfContentByte.ALIGN_CENTER, "" + currentPageNumber + " of " + totalPages, 520, 5, 0);
          cb.endText();
          pageOfCurrentReaderPDF = 0;
          } catch (Exception e) {
          e.printStackTrace();
          } finally {
               System.out.println("SUCCESS");
          /*try {
          if (outputStream != null);
          //outputStream.close();
          } catch (IOException ioe) {
          ioe.printStackTrace();
thanks in advance
regards
Oasisdeserts

Answer 1

thanks for your reply,
i already tried open and close the output stream and Input Stream to read and write every PDF,but i conflicted that that last PDF only is written in the final merged PDF.so what can i do to this every time the new PDF is to take to merge with already merged PDF.
i want know about CODE TAGS
As per your succession,
for(int i =0 ;i<200;i++){
               output = new FileOutputStream("E:\\templates\\out\\Merged PDF\\merge.pdf",true);
               document.open();
               String value     = "E:\\templates\\out\\07J439HF_FINAL_EVALU.pdf";
               ConcatPDFs.concatPDFs(document,writer,value, true);
               output.flush();
               document.close();
               output.close();
thanks
regards
Edited by: oasisdesert on Oct 22, 2008 3:03 AM