Getting metadata from PDF files

There are times when you need info about the PDF file itself (metadata). For instance, you might want to know the Author, or the date is was created etc. 
There is no guarantee that all PDF files will have all the metadata you need as some fields are optional. The following code describes how to get the metadata.

package
com.printmyfolders.demo; import java.io.IOException; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.PDDocumentInformation; import java.util.Calendar; import java.text.SimpleDateFormat; /**  *  * @author Stephen H  * Created 9 July 2014  * Revised 17 July 2014  * Email steve@printmyfolders.com  *  * An example showing how to get info about a PDF file.  * Here is how it works  * 1. Load a PDF file. Make provisions to catch or throw IOException.  * 2. Call the getDocumentInformation() method on the PDDocument object.  * 3. Call the different get methods on the resulting PDDocumentInformation object.  * 4. The methods are         getTitle() - Will get the document's title as a String. Can return null.         getAuthor() - Will get the name of the person who created the String. Can return null.         getSubject() - Will get the Subject as a String. Can return null.         getKeywords() - Will get the Keywords for this document as a String. Can return null.         getCreator() - Will get the Creator of the doc as a String. Can return null.         getProducer() - Will get the format from which the PDF was converted (if it was converted)         For example, a document that I created in Ms Word and converted to a PDF using a free PDF         converting tool had the creator as "PScript5.dll Version 5.2.2". Can return null.         getCreationDate() - Will get the Creation date and time as a Calendar object. Can return null.         getModificationDate() - Will get the date and time when the PDF was most recently modified         as a Calendar object. Can return null.         getTrapped() - Gets the trapped value as a String. Can return null. Look at the link below for more information on Trapped.                  *** For more info refer to http://www.adobe.com/devnet/acrobat/pdfs/PDF32000_2008.pdf (Page 550). ***  * 5. Create a static method to convert Calendar to date format dd-MM-yyyy. WARNING: I am not sure if my steps are right.  */ public class PDFInfo { static String getProperDate(Calendar cal){ // We use this method to convert the Calendar object to a more readable date. // WARNING: I am not sure if my steps are right. SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy"); String properDate = dateFormat.format(cal.getTime()); return properDate; } public static void main(String[] args) throws IOException { // Load the PDF. The PDDocument throws IOException PDDocument document = new PDDocument(); document = PDDocument.load("C:\\Document1.pdf"); // Get the PDDocumentInformation object from the PDDocument that you created PDDocumentInformation info = document.getDocumentInformation(); // Refer to the comments at the start of the code System.out.println("Title " + info.getTitle()); System.out.println("Author " + info.getAuthor()); System.out.println("Subject " + info.getSubject()); System.out.println("Keywords " + info.getKeywords()); System.out.println("Creator " + info.getCreator()); System.out.println("Producer " + info.getProducer()); System.out.println("Created date " + getProperDate(info.getCreationDate())); System.out.println("Modified date " + getProperDate(info.getModificationDate())); System.out.println("Trapped " + info.getTrapped()); } }

Sample Outputs:
This output is from a PDF that I created by printing from a PDF through a third party PDF creator.
Title Microsoft Word - Document1
Author Steve
Subject null
Keywords null
Creator PScript5.dll Version 5.2.2
Producer GPL Ghostscript 8.15
Created date 09-07-2014
Modified date 09-07-2014
Trapped null

This output is from the Adobe specification PDF (http://www.adobe.com/devnet/acrobat/pdfs/PDF32000_2008.pdf)

Title PDF32000.book
Author Jim King
Subject null
Keywords null
Creator FrameMaker 8.0
Producer Acrobat Distiller 8.1.0 (Windows)
Created date 18-09-2008
Modified date 30-09-2008
Trapped null

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