package partialcopy;


import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
/*
 * $Id: PartialCopyFile.java 29 2016-06-02 13:29:57Z conan $
 */
public class PartialCopyFile {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		if (args.length < 3) {
			System.err.println("PartialCopyFile needs a file name a starting byte and a size");
			return;
		}
		try {
			long start, count;
			RandomAccessFile rin = new RandomAccessFile(args[0], "r");
			FileChannel fcin = rin.getChannel();
			RandomAccessFile rout = new RandomAccessFile("copy.out","rw");
			FileChannel fcout = rout.getChannel();
			
			start = Long.parseLong(args[1]);
			count = Integer.parseInt(args[2]);
			MappedByteBuffer bufin = fcin.map(MapMode.READ_ONLY, start, count);
			MappedByteBuffer bufout = fcout.map(MapMode.READ_WRITE, 0L, count); 

			bufout.put(bufin);
			
		} catch (FileNotFoundException fnfe) {
			System.out.println(fnfe);
		} catch (IOException ioe) {
			System.out.println(ioe);
		} catch (NumberFormatException nfe){
			System.out.println(nfe);

		}
	}
}