FileInputStream fin = null; // Streams to the two files.
FileOutputStream fout = null; // These are closed in the finally block.
try {
// Open a stream to for the input file and get a channel from it
fin = new FileInputStream(args[0]);
FileChannel in = fin.getChannel();
// Now get the output channel
WritableByteChannel out;
if (args.length > 1) { // If there is a second filename
fout = new FileOutputStream(args[1]); // open file stream
out = fout.getChannel(); // get its channel
}
else { // There is no destination filename
out = Channels.newChannel(System.out); // wrap stdout stream
}
// Query the size of the input file
long numbytes = in.size();
// Bulk-transfer all bytes from one channel to the other.
// This is a special feature of FileChannel channels.
// See also FileChannel.transferFrom()
in.transferTo(0, numbytes, out);
}
catch(IOException e) {
// IOExceptions usually have useful informative messages.
// Display the message if anything goes wrong.
System.out.println(e);
}
finally {
// Always close input and output streams. Doing this closes
// the channels associated with them as well.
try {
if (fin != null) fin.close();
if (fout != null) fout.close();
}
catch(IOException e) {}
}
