Fastest way to copy files in Java

Question

Hi,

What ist the fastest way to copy a big number of files in Java. So far I have used file streams and nio. Overall streams seem to be faster than nio. What experiences did you make so far?

Answer 1

Have java fork off an OS batch script that copies the files. Your code might have to write the batch script.

Answer 2

I would use:

import java.io.*;
import java.nio.channels.*;

public class FileUtils{
    public static void copyFile(File in, File out) 
        throws IOException 
    {
        FileChannel inChannel = new
            FileInputStream(in).getChannel();
        FileChannel outChannel = new
            FileOutputStream(out).getChannel();
        try {
            inChannel.transferTo(0, inChannel.size(),
                    outChannel);
        } 
        catch (IOException e) {
            throw e;
        }
        finally {
            if (inChannel != null) inChannel.close();
            if (outChannel != null) outChannel.close();
        }
    }

    public static void main(String args[]) throws IOException{
        FileUtils.copyFile(new File(args[0]),new File(args[1]));
  }
}

If any of your files are bigger than 64M in Windows you might need to look at this: http://forums.sun.com/thread.jspa?threadID=439695&messageID=2917510

Answer 3

http://www.baptiste-wicht.com/2010/08/file-copy-in-java-benchmark/ might get you your answer.