What is the most efficient (fastest) way to concatenate two large (over 1.5GB) files in java?

Question

I have utilized the techniques here and concatenated two 1.5GB files in 70 seconds.

http://nadeausoftware.com/articles/2008/02/java_tip_how_read_files_quickly

My code involved using FileChannels with memory mapping and ByteBuffers with an 8KB buffer size.

How could I improve this speed?

File file = new File(binDirectory + "/donjon.avi");
File oFile = new File(binDirectory + "/donjon2.avi");

FileInputStream is = new FileInputStream(file);
FileOutputStream fos = new FileOutputStream(oFile);
FileChannel f1 = is.getChannel();
FileChannel f2 = fos.getChannel();

f2.transferFrom(f1, 0, f1.size());
f2.transferFrom(f1, f1.size(), f1.size());

f2.close();
f1.close();

Answer 1

try this

    FileChannel c1 = new FileInputStream("1").getChannel();
    FileChannel c2 = new FileOutputStream("2", true).getChannel();
    c2.transferFrom(c1, c2.size(), c1.size());

javadoc says that FileChannel.transferFrom is potentially much more efficient than a simple loop that reads from this channel and writes to the target channel. Many operating systems can transfer bytes directly from the filesystem cache to the target channel without actually copying them.