Split PDF by Size Java Example iText Tutorial

In this new iText tutorial, we will explain how to split a PDF file by size with an example. We earlier presented an example to slice a PDF document based on the number of pages in Java. But quite often, you may have to divide a PDF document based on size and not by number of pages. Hence, it would be handy to define an approach to achieve this kind of size based PDF split. For this demonstration, I have an input PDF file of size ~2 MB and I would like to size this PDF into smaller chunks of 500 Kb files. We will provide a working Java code example that will demonstrate how to split this PDF into smaller chunks of PDF files based on size. We will get started with the step by step guide now.

Step-1: Begin with creating a PdfReader object that will accept the incoming PDF file that needs to be split based on size. We also create a Document and PdfCopy object at this stage as the final output would atleast have one PDF file. The Java Code to achieve this is provided below;

          PdfReader Split_PDF_By_Size = new PdfReader("CombinedPDFDocument.pdf");          
          Document document=new Document();; 
          PdfCopy copy=new PdfCopy(document,new FileOutputStream("File1.pdf"));
          document.open();          

Step-2: Eventhough the split is based on size, we still have to get the number of pages in the incoming PDF file. We use getNumberofPages in Document class to get this information for us. I will also declare an integer variable to dynamically name the new files and an integer variable that will hold the size of the new PDF as we import pages into it from original PDF file. I will also declare a float variable to get the size in kilobytes and check it for creating subsequent new files. The variable declarations are provided below;

          int number_of_pages = Split_PDF_By_Size.getNumberOfPages();
          int pagenumber=1;
          int Find_PDF_Size;
          float combinedsize=0;        

Step-3:We now declare a for loop for the number of pages in input PDF. Inside this loop, we import pages from original document to new PDF document using getImportedPage method. We also use getCurrentDocumentSize method of PdfCopy object to inspect the size of the Document after page import. This size is returned to us in bytes and I divide it by 1024 to convert it to kilobytes in Java. If this size exceeds 496 Kb (I want to reserve 4 Kb for EOF information) or if the page being imported is the last page in the input PDF file, we can close the Document object and reset combinedsize to 0. In a scenario where the size has exceeded our limit, we create a new Document object when the loop runs again, and add pages to the new PDF file. The code to run this for loop is provided below;

          for (int i = 1; i < number_of_pages; i++ ) {
                  if (combinedsize==0 && i !=1 ){                   
                  document = new Document();
                  pagenumber++;
                  String FileName="File"+ pagenumber+".pdf";                     
                  copy = new PdfCopy(document,new FileOutputStream(FileName));
                  document.open();   
                  }
                  copy.addPage(copy.getImportedPage(Split_PDF_By_Size, i));
                  Find_PDF_Size=copy.getCurrentDocumentSize();            
                  combinedsize=(float)Find_PDF_Size/1024;                 
                  if (combinedsize > 496 || i==number_of_pages) {
                  document.close();
                  combinedsize=0;
                  }
                                }

Step-4: The For Loop in Step 3 does all the size based split of PDF file for us. At the end of the loop, we can put a simple print statement in Java to print the number of new files that got created.

The complete commented version of the Java Code to Split a PDF file based on Size using the iText library is provided below;

import java.io.*;
import com.itextpdf.text.*;
import com.itextpdf.text.pdf.*;
public class SplitPDFBySize {  
     public static void main(String[] args){
        try {
          PdfReader Split_PDF_By_Size = new PdfReader("CombinedPDFDocument.pdf");          
          Document document=new Document();; 
          PdfCopy copy=new PdfCopy(document,new FileOutputStream("File1.pdf"));
          document.open();          
          int number_of_pages = Split_PDF_By_Size.getNumberOfPages();
          int pagenumber=1; /* To generate file name dynamically */
          int Find_PDF_Size; /* To get PDF size in bytes */
          float combinedsize=0; /* To convert this to Kilobytes and estimate new PDF size */        
          for (int i = 1; i < number_of_pages; i++ ) {
                  if (combinedsize==0 && i !=1 ){ /* Generate new file only for second time when first document size
                          exceeds limit and incoming loop counter is not 1 */
                  document = new Document();
                  pagenumber++;
                  String FileName="File"+ pagenumber+".pdf"; /* Dynamic file name */                    
                  copy = new PdfCopy(document,new FileOutputStream(FileName));
                  document.open();   
                  }
                  copy.addPage(copy.getImportedPage(Split_PDF_By_Size, i)); /* Import pages from original document */
                  Find_PDF_Size=copy.getCurrentDocumentSize(); /* Estimate PDF size in bytes */           
                  combinedsize=(float)Find_PDF_Size/1024; /* Convert bytes to kilobytes */                
                  if (combinedsize > 496 || i==number_of_pages) { /* Close document if the page is the last page or if limit reaches */
                  document.close();
                  combinedsize=0; /* reset variable to generate next file, if required */
                  }
                                }
          System.out.println("PDF Split By Size Completed. Number of Documents Created:"+pagenumber);                        
        }
        catch (Exception i)
        {
            System.out.println(i);
        }
    }
}

In my case, I got 7 PDF documents each of size ~ 500 Kb. I could understand that the split is not an equivalent File Split as we have to generate header information for all PDF files.We will dwell more on this in upcoming tutorials

Do you know a better way to chunk PDF files by Size? Share your thoughts on this code with us.