Java Writing all pdf files bytes in .dat file

Question

I wrote the code write all pdf files in folder get bytes and write in .dat file.. Acutally its working and writing all bytes in .dat file but When I open that .dat file with Acrobat it open with black page.

Here is my code..

    import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Calendar;

public class xmlfile1filebytes {

  public static void main(String[] args) throws IOException {

    File folder = new File ("07072013");
    File[] listOfFiles = folder.listFiles();

    System.out.println("There are " + listOfFiles.length + " files"); 
    String filesin;

    String timeStamp = new SimpleDateFormat("MM-dd-yyyy[HH.mm.ss]")
     .format(Calendar.getInstance().getTime());
     System.out.println(timeStamp);

    BufferedWriter xmlfile = null;
    BufferedWriter datfile = null;

    String outxmlfile = ("07072013\\" + timeStamp + ".xml");
    xmlfile = new BufferedWriter(new FileWriter(outxmlfile));

    String outdatfile = ("07072013\\" + timeStamp + ".dat");
    datfile = new BufferedWriter(new FileWriter(outdatfile));

    int offset = 0;
    int size = 0;

    for (int i = 0; i < listOfFiles.length; i++) {

        File f = listOfFiles[i];

       // System.out.println(i + " " + f.getAbsolutePath());
        if (f.isFile()) {

            filesin = listOfFiles[i].getName();

            if (filesin.endsWith("pdf")) {

                Path aPath = Paths.get(f.getAbsolutePath()); 

                System.out.println(filesin);

                byte[] actualBytes = Files.readAllBytes(aPath);
                size = actualBytes.length;

                xmlfile.append((i + 1) + ")" + " File = " + filesin + ", Offset = " + offset + ", Size = " + size + "\n");


                offset = offset + size;
                xmlfile.newLine();

                String s = new String(actualBytes);

                datfile.append(s);
                datfile.newLine();


                File datfileinfolder = new File ("07072013\\" + timeStamp + ".dat");

                long datfilesize = datfileinfolder.length();
                final int BLOCK_SIZE = 200 * 1024;

                for (int curBlock = 0;  curBlock < actualBytes.length; curBlock += BLOCK_SIZE) {
                    String toWrite = new String(
                            Arrays.copyOfRange(actualBytes, curBlock, Math.min(curBlock + BLOCK_SIZE, actualBytes.length)));

                     String suffix = "";

                     if (curBlock > 0) {
                         //append underscores other file information and then perform writes
                         suffix =  String.valueOf(curBlock /  BLOCK_SIZE);
                     }    

                     BufferedWriter datfile1 = null;
                     String outdatfile1 = ("07072013\\" + suffix + timeStamp + ".dat");
                     datfile1 = new BufferedWriter(new FileWriter(outdatfile1));


                     datfile1.append(toWrite);
                     datfile1.close(); 

                }

                //long datfilesizeinkb = datfilesize /1024;

                //System.out.println("Size = " + datfilesizeinkb);



             }
        }
    }
     datfile.close();
     xmlfile.close();
  }
}

Answer 1

It's unclear from your post and your comments what you're really trying to accomplish. Your original question seemed to be about merging multiple PDF files into a single .dat file, which you expected to be able to open with acrobat.

If that's what you're trying to do, then I suggest using Apache PDFBox and in particular the PDFMergerUtility class. An outline of the code would be like this:

PDFMergerUtility merger = new PDFMergerUtility();
File[] files = folder.listFiles();
for (File file : files) {
    merger.addSource(file);
}

merger.setDestinationFileName("output.pdf");
merger.mergeDocuments();

That should combine your source files into a single large PDF file. You could, of course, use a .dat extension on this file, but I'm not sure why you would do so. The only thing that would accomplish is to break the file extension association so double-clicking the file wouldn't open it.

The second question you were asking was how you break the data into 200KB chunks. I'm unsure why you want do do this. If you do this, you will not (necessarily) be able to open the resulting files in Acrobat. PDF files are pretty specific about their internal format. Partial files will not open. If the goal is to have one output file for each input file, then a simple file copy would accomplish this. If the goal is to take all of these files and merge them into a single stream in 200KB chunks (again, why?), then you might want to consider using a compression library instead. In that case, this answer may get you started.