Merging PDF Files and Retaining Interactive Fields Using the Datalogics PDF Java Toolkit

MergeFormsRetainingFields.java

/*
 * Copyright Datalogics, Inc. 2015
 */

package pdfjt.cookbook.combine;

import com.adobe.internal.io.ByteReader;
import com.adobe.internal.io.ByteWriter;
import com.adobe.internal.io.InputStreamByteReader;
import com.adobe.pdfjt.core.types.ASRectangle;
import com.adobe.pdfjt.pdf.document.PDFDocument;
import com.adobe.pdfjt.pdf.document.PDFOpenOptions;
import com.adobe.pdfjt.pdf.document.PDFSaveFullOptions;
import com.adobe.pdfjt.pdf.document.PDFVersion;
import com.adobe.pdfjt.pdf.interactive.forms.PDFField;
import com.adobe.pdfjt.pdf.interactive.forms.PDFInteractiveForm;
import com.adobe.pdfjt.services.manipulations.PMMOptions;
import com.adobe.pdfjt.services.manipulations.PMMService;

import java.io.File;
import java.io.FileInputStream;
import java.util.Iterator;

import pdfjt.util.SampleFileServices;

public class MergeFormsRetainingFields {

	private static final String inputDir = "cookbook/MergeForms/input";
	private static final String outputDir = "cookbook/MergeForms/output";
	private static final String outputFilename = "MergedFormsWithFields.pdf";

	/**
	 * @param args
	 */
	public static void main(String[] args) throws Exception{
	/*
         * Start by creating a new PDF document that will be used to merge the
         * other documents into. The new document will contain a single blank page
         * but we'll remove this just before saving the merged file.
         */
		PDFDocument mergedDocument = PDFDocument.newInstance(
				new ASRectangle(new double[]{ 0, 0, 612, 792}), 
				PDFOpenOptions.newInstance());
		/*
		 * Create the new PMMService that will be used to manipulate the pages.
		 */
		PMMService pmmService = new PMMService(mergedDocument);
		
		try {
            /*
             * Add the files in the input directory to the new PDF file. This
             * process will append the pages from each document to the end of
             * the new document creating a continuous series of pages. 
             * 
             * Folders will be skipped.
             */
	        File root = new File(inputDir);
	        File[] list = root.listFiles();
	        if (list == null) return;
	        for (File pdfFile : list) {
	            if (pdfFile.isDirectory() == false) {
	                String pdfFileName = pdfFile.getName();
	                FileInputStream fis = new FileInputStream(pdfFile);
	                ByteReader byteReader = new InputStreamByteReader(fis);
	                PDFDocument pdfToAppend = PDFDocument.newInstance(byteReader, PDFOpenOptions.newInstance());
	                String pdfBaseFileName  = pdfFileName.substring(0,  pdfFileName.length() - 4);
                    /*
                     * Unless the following step is taken, form fields with the
                     * same name will be merged and assume the value of the
                     * first field encountered during the append.
                     * 
                     * To ensure that each field in the combined file has a
                     * unique name, we'll prepend the file name to the field
                     * name prior to combining.
                     */
	                
	                // Get the form and then the field iterator
	                PDFInteractiveForm pdfInteractiveForm = pdfToAppend.getInteractiveForm();
	                Iterator<PDFField> fieldIterator = pdfInteractiveForm.iterator();
	                // Iterator over form fields
	                while(fieldIterator.hasNext()) {
	                    PDFField pdfField = (PDFField)(fieldIterator.next());
	                    //Change the field name
	                    pdfField.setPartialName(pdfBaseFileName+"."+pdfField.getPartialName());
	                }
	                // Now append the PDF with the modified field names.
	                System.out.println("Appending " + pdfFileName + " to the end of "+outputFilename);
	                pmmService.appendPages(pdfToAppend, null, PMMOptions.newInstanceAll());
	                byteReader.close();
	            }
	        }    
			/*
			 * Remove the first page. We don't need it anymore.
			 */
			mergedDocument.requirePages().removePage(mergedDocument.requirePages().getPage(0));

			/*
			 * Save the file
			 */
			ByteWriter outputWriter = SampleFileServices.getRAFByteWriter(outputDir + File.separator + outputFilename);
			mergedDocument.save(outputWriter, PDFSaveFullOptions.newInstance(PDFVersion.v1_7));
			System.out.println("Created "+outputFilename +" with "+mergedDocument.requirePages().getCount()+" pages");
			mergedDocument.close();
			outputWriter.close();
		} finally {
			//
		}

	}	
}