/**Program for converting each page of a PDF to JPEG images.
 * @author James R. Schmidt*/
package pdftojpg;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.List;
import java.util.stream.Collectors;
import javax.swing.JOptionPane;
import org.apache.pdfbox.pdmodel.*;
import org.apache.pdfbox.rendering.*;
import org.apache.pdfbox.tools.imageio.ImageIOUtil;

public class Main{
 /**Main method
  * @param args Not used*/
 public static void main(String[] args){
  String dir = System.getProperty("user.dir")+
               System.getProperty("file.separator")+"data";
  List fileList;
  Object[] fileNames = new Object[0];
  try{
   fileList = Files.walk(Paths.get(dir))
                   .filter(str -> str.getFileName().toString().endsWith("pdf"))
                   .collect(Collectors.toList());
   fileNames = fileList.toArray();
  }
  catch(IOException e1){
   System.out.println("Error in finding data files.");
  }
  int iNum = 0;
  for(Object fN : fileNames){
   String fileName = fN.toString();
   try{
    PDDocument document = PDDocument.load(new File(fileName));
    PDFRenderer pdfRenderer = new PDFRenderer(document);
    for(int page=0; page<document.getNumberOfPages(); ++page,++iNum){
     BufferedImage bi = pdfRenderer.renderImageWithDPI(page,300,ImageType.RGB);
     ImageIOUtil.writeImage(bi, "output" + (iNum+1) + ".jpg", 300);
    }
    document.close();
   }
   catch(Exception ex){
    JOptionPane.showMessageDialog(null, ex.getStackTrace());
   }
  }
 }
}