Example usage for java.nio.channels FileChannel position

List of usage examples for java.nio.channels FileChannel position

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Introduction

In this page you can find the example usage for java.nio.channels FileChannel position.

Prototype

public abstract long position() throws IOException;

Source Link

Document

Returns this channel's file position.

Usage

From source file:Main.java

public static void main(String[] args) throws IOException {

    int i = 0;//from  ww  w  .  j  av  a 2  s .  co m

    FileInputStream fis = new FileInputStream("C://test.txt");

    // read till the end of the file
    while ((i = fis.read()) != -1) {
        // get file channel
        FileChannel fc = fis.getChannel();

        // get channel position
        long pos = fc.position();

        char c = (char) i;

        System.out.println("No of bytes read: " + pos);
        System.out.println("Char read: " + c);
    }
}

From source file:Main.java

public static void main(String[] args) throws IOException {

    byte b[] = { 65, 66, 67, 68, 69 };

    FileOutputStream fos = new FileOutputStream("C://test.txt");

    fos.write(b);/*from   w  w  w  . jav  a 2 s  .co  m*/

    // pushes stream content to the underlying file
    fos.flush();

    // returns file channel associated with this stream
    FileChannel fc = fos.getChannel();

    // returns the number of bytes written
    long pos = fc.position();

    System.out.print(pos);

}

From source file:MainClass.java

public static void main(String[] argv) throws IOException {
    RandomAccessFile randomAccessFile = new RandomAccessFile("test.dat", "r");

    randomAccessFile.seek(1000);//from  w  w w. j  a v a2s .  c om

    FileChannel fileChannel = randomAccessFile.getChannel();

    // This will print "1000"
    System.out.println("file pos: " + fileChannel.position());

    randomAccessFile.seek(500);

    // This will print "500"
    System.out.println("file pos: " + fileChannel.position());

    fileChannel.position(200);

    // This will print "200"
    System.out.println("file pos: " + randomAccessFile.getFilePointer());
}

From source file:Main.java

public static boolean fileCopy(File srcFile, File dstFile) {
    int length = 1048891;
    FileChannel inC = null;
    FileChannel outC = null;//from  w  ww  .  j a  v  a2s  .co  m
    try {
        FileInputStream in = new FileInputStream(srcFile);
        FileOutputStream out = new FileOutputStream(dstFile);
        inC = in.getChannel();
        outC = out.getChannel();
        ByteBuffer b = null;
        while (inC.position() < inC.size()) {
            if ((inC.size() - inC.position()) < length) {
                length = (int) (inC.size() - inC.position());
            } else {
                length = 1048891;
            }
            b = ByteBuffer.allocateDirect(length);
            inC.read(b);
            b.flip();
            outC.write(b);
            outC.force(false);
        }

        return true;
    } catch (IOException e) {
        e.printStackTrace();
        return false;
    } finally {
        try {
            if (inC != null && inC.isOpen()) {
                inC.close();
            }
            if (outC != null && outC.isOpen()) {
                outC.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

From source file:org.grouplens.lenskit.data.dao.packed.BinaryRatingDAO.java

/**
 * Open a binary rating DAO./*from ww w  .j a  v  a 2s  . c  om*/
 * @param file The file to open.
 * @return A DAO backed by {@code file}.
 * @throws IOException If there is
 */
public static BinaryRatingDAO open(File file) throws IOException {
    FileInputStream input = new FileInputStream(file);
    try {
        FileChannel channel = input.getChannel();
        BinaryHeader header = BinaryHeader.read(channel);
        logger.info("Loading DAO with {} ratings of {} items from {} users", header.getRatingCount(),
                header.getItemCount(), header.getUserCount());

        ByteBuffer data = channel.map(FileChannel.MapMode.READ_ONLY, channel.position(),
                header.getRatingDataSize());
        channel.position(channel.position() + header.getRatingDataSize());

        ByteBuffer tableBuffer = channel.map(FileChannel.MapMode.READ_ONLY, channel.position(),
                channel.size() - channel.position());
        BinaryIndexTable utbl = BinaryIndexTable.fromBuffer(header.getUserCount(), tableBuffer);
        BinaryIndexTable itbl = BinaryIndexTable.fromBuffer(header.getItemCount(), tableBuffer);

        return new BinaryRatingDAO(file, header, data, utbl, itbl);
    } finally {
        input.close();
    }
}

From source file:org.solmix.commons.util.Files.java

/**
 * ?// w w w . ja  va 2s. c  o m
 *
 * @param f1
 *            ?
 * @param f2
 *            
 * @throws Exception
 */
public static void copyFile(File f1, File f2) throws Exception {
    int length = 2097152;
    FileInputStream in = new FileInputStream(f1);
    FileOutputStream out = new FileOutputStream(f2);
    FileChannel inC = in.getChannel();
    FileChannel outC = out.getChannel();
    ByteBuffer b = null;
    while (true) {
        if (inC.position() == inC.size()) {
            inC.close();
            outC.close();
        }
        if ((inC.size() - inC.position()) < length) {
            length = (int) (inC.size() - inC.position());
        } else
            length = 2097152;
        b = ByteBuffer.allocateDirect(length);
        inC.read(b);
        b.flip();
        outC.write(b);
        outC.force(false);
    }
}

From source file:com.turn.ttorrent.common.TorrentCreator.java

/**
 * Return the concatenation of the SHA-1 hashes of a file's pieces.
 *
 * <p>/*from w  ww . j  a v  a  2 s. c o  m*/
 * Hashes the given file piece by piece using the default Torrent piece
 * length (see {@link #PIECE_LENGTH}) and returns the concatenation of
 * these hashes, as a string.
 * </p>
 *
 * <p>
 * This is used for creating Torrent meta-info structures from a file.
 * </p>
 *
 * @param file The file to hash.
 */
public /* for testing */ static byte[] hashFiles(Executor executor, List<File> files, long nbytes,
        int pieceLength) throws InterruptedException, IOException {
    int npieces = (int) Math.ceil((double) nbytes / pieceLength);
    byte[] out = new byte[Torrent.PIECE_HASH_SIZE * npieces];
    CountDownLatch latch = new CountDownLatch(npieces);

    ByteBuffer buffer = ByteBuffer.allocate(pieceLength);

    long start = System.nanoTime();
    int piece = 0;
    for (File file : files) {
        logger.info("Hashing data from {} ({} pieces)...",
                new Object[] { file.getName(), (int) Math.ceil((double) file.length() / pieceLength) });

        FileInputStream fis = FileUtils.openInputStream(file);
        FileChannel channel = fis.getChannel();
        int step = 10;

        try {
            while (channel.read(buffer) > 0) {
                if (buffer.remaining() == 0) {
                    buffer.flip();
                    executor.execute(new ChunkHasher(out, piece, latch, buffer));
                    buffer = ByteBuffer.allocate(pieceLength);
                    piece++;
                }

                if (channel.position() / (double) channel.size() * 100f > step) {
                    logger.info("  ... {}% complete", step);
                    step += 10;
                }
            }
        } finally {
            channel.close();
            fis.close();
        }
    }

    // Hash the last bit, if any
    if (buffer.position() > 0) {
        buffer.flip();
        executor.execute(new ChunkHasher(out, piece, latch, buffer));
        piece++;
    }

    // Wait for hashing tasks to complete.
    latch.await();
    long elapsed = System.nanoTime() - start;

    logger.info("Hashed {} file(s) ({} bytes) in {} pieces ({} expected) in {}ms.",
            new Object[] { files.size(), nbytes, piece, npieces, String.format("%.1f", elapsed / 1e6) });

    return out;
}

From source file:org.lenskit.data.packed.BinaryRatingDAO.java

/**
 * Open a binary rating DAO.//from ww  w.ja  v a2s .  c om
 *
 * @param file The file to open.
 * @return A DAO backed by {@code file}.
 * @throws IOException If there is
 */
public static BinaryRatingDAO open(File file) throws IOException {
    try (FileInputStream input = new FileInputStream(file)) {
        FileChannel channel = input.getChannel();
        BinaryHeader header = BinaryHeader.read(channel);
        logger.info("Loading DAO with {} ratings of {} items from {} users", header.getRatingCount(),
                header.getItemCount(), header.getUserCount());
        // the channel position has been advanced to end of header

        ByteBuffer data = channel.map(FileChannel.MapMode.READ_ONLY, channel.position(),
                header.getRatingDataSize());
        channel.position(channel.position() + header.getRatingDataSize());

        ByteBuffer tableBuffer = channel.map(FileChannel.MapMode.READ_ONLY, channel.position(),
                channel.size() - channel.position());
        BinaryIndexTable utbl = BinaryIndexTable.fromBuffer(header.getUserCount(), tableBuffer);
        BinaryIndexTable itbl = BinaryIndexTable.fromBuffer(header.getItemCount(), tableBuffer);

        return new BinaryRatingDAO(file, header, data, utbl, itbl, header.getRatingCount(), Long.MAX_VALUE);
    }
}

From source file:me.carpela.network.pt.cracker.tools.ttorrent.Torrent.java

private static String hashFiles(List<File> files, int pieceLenght)
        throws InterruptedException, IOException, NoSuchAlgorithmException {
    int threads = getHashingThreadsCount();
    ExecutorService executor = Executors.newFixedThreadPool(threads);
    ByteBuffer buffer = ByteBuffer.allocate(pieceLenght);
    List<Future<String>> results = new LinkedList<Future<String>>();
    StringBuilder hashes = new StringBuilder();

    long length = 0L;
    int pieces = 0;

    long start = System.nanoTime();
    for (File file : files) {

        length += file.length();//  w w w . j  a v  a2  s.  c o m

        FileInputStream fis = new FileInputStream(file);
        FileChannel channel = fis.getChannel();
        int step = 10;

        try {
            while (channel.read(buffer) > 0) {
                if (buffer.remaining() == 0) {
                    buffer.clear();
                    results.add(executor.submit(new CallableChunkHasher(buffer)));
                }

                if (results.size() >= threads) {
                    pieces += accumulateHashes(hashes, results);
                }

                if (channel.position() / (double) channel.size() * 100f > step) {
                    step += 10;
                }
            }
        } finally {
            channel.close();
            fis.close();
        }
    }

    // Hash the last bit, if any
    if (buffer.position() > 0) {
        buffer.limit(buffer.position());
        buffer.position(0);
        results.add(executor.submit(new CallableChunkHasher(buffer)));
    }

    pieces += accumulateHashes(hashes, results);

    // Request orderly executor shutdown and wait for hashing tasks to
    // complete.
    executor.shutdown();
    while (!executor.isTerminated()) {
        Thread.sleep(10);
    }
    long elapsed = System.nanoTime() - start;

    int expectedPieces = (int) (Math.ceil((double) length / pieceLenght));
    return hashes.toString();
}

From source file:org.cloudata.core.commitlog.FileTransferThread.java

private void transfer(FileChannel[] channelList, SocketChannel socketChannel) {
    for (FileChannel fc : channelList) {
        try {// w ww. j  av a 2s  .  co m
            long numTransferred = 0;
            long pos = fc.position();
            long totalLength = fc.size() - pos;
            long count = totalLength;

            LOG.info(dirName + " start File Transfer:" + pos + "," + totalLength);
            while ((numTransferred += fc.transferTo(pos, count, socketChannel)) < totalLength) {
                pos += numTransferred;
                count -= numTransferred;
            }
            //LOG.info("End File Transfer:" + pos + "," + totalLength);
        } catch (IOException e) {
            LOG.warn("transfering file is fail due to : ", e);
        } finally {
            if (fc != null) {
                try {
                    fc.close();
                } catch (IOException e) {
                    LOG.warn("closing file is fail due to : ", e);
                }
            }
        }
    }
}