Fastest way to copy files in Java

Question

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 mak

Answer 1

Using Stream

private static void copyFileUsingStream(File source, File dest) throws IOException {
    InputStream is = null;
    OutputStream os = null;
    try {
        is = new FileInputStream(source);
        os = new FileOutputStream(dest);
        byte[] buffer = new byte[1024];
        int length;
        while ((length = is.read(buffer)) > 0) {
            os.write(buffer, 0, length);
        }
    } finally {
        is.close();
        os.close();
    }
}

Using Channel

private static void copyFileUsingChannel(File source, File dest) throws IOException {
    FileChannel sourceChannel = null;
    FileChannel destChannel = null;
    try {
        sourceChannel = new FileInputStream(source).getChannel();
        destChannel = new FileOutputStream(dest).getChannel();
        destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());
       }finally{
           sourceChannel.close();
           destChannel.close();
       }
}

Using Apache Commons IO

private static void copyFileUsingApacheCommonsIO(File source, File dest) throws IOException {
    FileUtils.copyFile(source, dest);
}

Using Java SE 7 Files

private static void copyFileUsingJava7Files(File source, File dest) throws IOException {
    Files.copy(source.toPath(), dest.toPath());
}

Performance test

File source = new File("/Users/tmp/source.avi");
File dest = new File("/Users/tmp/dest.avi");

//copy file conventional way using Stream
long start = System.nanoTime();
copyFileUsingStream(source, dest);
System.out.println("Time taken by Stream Copy = "+(System.nanoTime()-start));

//copy files using java.nio FileChannel
source = new File("/Users/tmp/sourceChannel.avi");
dest = new File("/Users/tmp/destChannel.avi");
start = System.nanoTime();
copyFileUsingChannel(source, dest);
System.out.println("Time taken by Channel Copy = "+(System.nanoTime()-start));

//copy files using apache commons io
source = new File("/Users/tmp/sourceApache.avi");
dest = new File("/Users/tmp/destApache.avi");
start = System.nanoTime();
copyFileUsingApacheCommonsIO(source, dest);
System.out.println("Time taken by Apache Commons IO Copy = "+(System.nanoTime()-start));

//using Java 7 Files class
source = new File("/Users/tmp/sourceJava7.avi");
dest = new File("/Users/tmp/destJava7.avi");
start = System.nanoTime();
copyFileUsingJava7Files(source, dest);
System.out.println("Time taken by Java7 Files Copy = "+(System.nanoTime()-start));

RESULTS

Time taken by Stream Copy            =  44,582,575,000
Time taken by Java7 Files Copy       =  89,061,578,000
Time taken by Channel Copy           = 104,138,195,000
Time taken by Apache Commons IO Copy = 108,396,714,000