Example usage for java.nio.channels FileChannel read

Introduction

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

Prototype

public final long read(ByteBuffer[] dsts) throws IOException 

Source Link

Document

Reads a sequence of bytes from this channel into the given buffers.

Usage

From source file:org.jasig.portlet.attachment.util.FileUtil.java

public static byte[] read(File file) throws IOException {
    if (file == null || !file.exists())
        return null;
    if (locks.contains(file.getAbsolutePath())) {
        try {//w w w.  ja va  2s .  c o  m
            Thread.sleep(100);
        } catch (InterruptedException ie) {
        }
    }

    FileInputStream input = null;
    try {
        input = new FileInputStream(file);
        int available = input.available();
        FileChannel channel = input.getChannel();
        ByteBuffer bytes = ByteBuffer.allocate(available);
        channel.read(bytes);
        bytes.flip();
        return bytes.array();
    } finally {
        if (input != null) {
            input.close();
        }
    }

}

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From source file:org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.MappableBlock.java

/**
 * Reads bytes into a buffer until EOF or the buffer's limit is reached
 *//*from  ww  w  .ja v a2s .  co  m*/
private static int fillBuffer(FileChannel channel, ByteBuffer buf) throws IOException {
    int bytesRead = channel.read(buf);
    if (bytesRead < 0) {
        //EOF
        return bytesRead;
    }
    while (buf.remaining() > 0) {
        int n = channel.read(buf);
        if (n < 0) {
            //EOF
            return bytesRead;
        }
        bytesRead += n;
    }
    return bytesRead;
}

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From source file:org.alfresco.repo.content.http.HttpAlfrescoStore.java

private static void doTest(ApplicationContext ctx, String baseUrl, String contentUrl) throws Exception {
    ServiceRegistry serviceRegistry = (ServiceRegistry) ctx.getBean(ServiceRegistry.SERVICE_REGISTRY);
    TransactionService transactionService = serviceRegistry.getTransactionService();
    AuthenticationService authenticationService = serviceRegistry.getAuthenticationService();
    // Construct the store
    HttpAlfrescoStore store = new HttpAlfrescoStore();
    store.setTransactionService(transactionService);
    store.setAuthenticationService(authenticationService);
    store.setBaseHttpUrl(baseUrl);//w w  w  .  j a va2s.c  om

    // Now test
    System.out.println("   Retrieving reader for URL " + contentUrl);
    ContentReader reader = store.getReader(contentUrl);
    System.out.println("   Retrieved reader for URL " + contentUrl);
    // Check if the content exists
    boolean exists = reader.exists();
    if (!exists) {
        System.out.println("   Content doesn't exist: " + contentUrl);
        return;
    } else {
        System.out.println("   Content exists: " + contentUrl);
    }
    // Get the content data
    ContentData contentData = reader.getContentData();
    System.out.println("   Retrieved content data: " + contentData);

    // Now get the content
    ByteBuffer buffer = ByteBuffer.allocate((int) reader.getSize());
    FileChannel channel = reader.getFileChannel();
    try {
        int count = channel.read(buffer);
        if (count != reader.getSize()) {
            System.err.println("The number of bytes read was " + count + " but expected " + reader.getSize());
            return;
        }
    } finally {
        channel.close();
    }
}

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From source file:Main.java

public static String readString(String filePath) {
    File file = new File(filePath);
    if (!file.exists())
        return null;

    FileInputStream fileInput = null;
    FileChannel channel = null;
    try {// ww w .j av a2 s. co  m
        fileInput = new FileInputStream(filePath);
        channel = fileInput.getChannel();
        ByteBuffer buffer = ByteBuffer.allocate((int) channel.size());
        channel.read(buffer);

        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        byteArrayOutputStream.write(buffer.array());
        return byteArrayOutputStream.toString();
    } catch (Exception e) {
    } finally {

        if (fileInput != null) {
            try {
                fileInput.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        if (channel != null) {
            try {
                channel.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    return null;
}

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From source file:com.log4ic.compressor.utils.FileUtils.java

/**
 * ?/*  ww w  . j  a  va2 s . c  om*/
 *
 * @param fileInputStream
 * @return
 */
public static String readFile(FileInputStream fileInputStream) throws IOException {
    ByteBuffer buffer = ByteBuffer.allocate(1024);
    StringBuffer contentBuffer = new StringBuffer();
    Charset charset = null;
    CharsetDecoder decoder = null;
    CharBuffer charBuffer = null;
    try {
        FileChannel channel = fileInputStream.getChannel();
        while (true) {
            buffer.clear();
            int pos = channel.read(buffer);
            if (pos == -1) {
                break;
            }
            buffer.flip();
            charset = Charset.forName("UTF-8");
            decoder = charset.newDecoder();
            charBuffer = decoder.decode(buffer);
            contentBuffer.append(charBuffer.toString());
        }
    } finally {
        if (fileInputStream != null) {
            try {
                fileInputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    return contentBuffer.toString();
}

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From source file:com.alibaba.otter.shared.common.utils.NioUtilsPerformance.java

public static void channelTest(File source, File target) throws Exception {
    FileInputStream fis = null;/*from  w w w . j av a2 s .  c  om*/
    FileOutputStream fos = null;
    try {
        fis = new FileInputStream(source);
        fos = new FileOutputStream(target);
        FileChannel sChannel = fis.getChannel();
        FileChannel tChannel = fos.getChannel();

        target.createNewFile();

        ByteBuffer buffer = ByteBuffer.allocate(16 * 1024);
        while (sChannel.read(buffer) > 0) {
            buffer.flip();
            tChannel.write(buffer);
            buffer.clear();
        }

        tChannel.close();
        sChannel.close();
    } finally {
        IOUtils.closeQuietly(fis);
        IOUtils.closeQuietly(fos);
    }
}

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From source file:com.sunchenbin.store.feilong.core.io.IOReaderUtil.java

/**
 * ?.//  w  w  w  . java  2  s.co  m
 *
 * @param file
 *            
 * @param charsetName
 *            ?,isNullOrEmpty, {@link CharsetType#UTF8}
 * @return the file content
 * @see org.apache.commons.io.FileUtils#readFileToString(File, Charset)
 */
public static String getFileContent(File file, String charsetName) {
    if (Validator.isNullOrEmpty(file)) {
        throw new NullPointerException("the file is null or empty!");
    }
    // ?
    final int capacity = 186140;
    ByteBuffer byteBuffer = ByteBuffer.allocateDirect(capacity);
    StringBuilder sb = new StringBuilder(capacity);

    FileInputStream fileInputStream = null;
    try {
        fileInputStream = new FileInputStream(file);

        // ?????.
        FileChannel fileChannel = fileInputStream.getChannel();
        String useCharsetName = Validator.isNullOrEmpty(charsetName) ? DEFAULT_CHARSET_NAME : charsetName;
        Charset charset = Charset.forName(useCharsetName);
        while (fileChannel.read(byteBuffer) != -1) {
            // ??
            byteBuffer.flip();
            CharBuffer charBuffer = charset.decode(byteBuffer);
            sb.append(charBuffer.toString());
            byteBuffer.clear();
        }
        return sb.toString();

    } catch (FileNotFoundException e) {
        throw new UncheckedIOException(e);
    } catch (IOException e) {
        throw new UncheckedIOException(e);
    } finally {
        // ? ,^_^
        IOUtils.closeQuietly(fileInputStream);
    }
}

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From source file:yui.classes.utils.IOUtils.java

public static byte[] fileReadNIO(String name) {
    FileInputStream f = null;/*w w  w .ja  v a  2 s.c  o m*/
    ByteBuffer bb = null;
    try {
        f = new FileInputStream(name);

        FileChannel ch = f.getChannel();
        bb = ByteBuffer.allocateDirect(1024);

        long checkSum = 0L;
        int nRead;
        while ((nRead = ch.read(bb)) != -1) {
            bb.position(0);
            bb.limit(nRead);
            while (bb.hasRemaining()) {
                checkSum += bb.get();
            }
            bb.clear();
        }
    } catch (FileNotFoundException ex) {
        logger.error(ex.getMessage());
    } catch (IOException ex) {
        logger.error(ex.getMessage());
    } finally {
        try {
            f.close();
        } catch (IOException ex) {
            logger.error(ex.getMessage());
        }
    }
    return bb.array();

}

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From source file:com.ery.ertc.estorm.util.IOUtils.java

/**
 * Reads len bytes in a loop using the channel of the stream
 * //from w  w  w . ja  v  a 2s. co  m
 * @param fileChannel
 *            a FileChannel to read len bytes into buf
 * @param buf
 *            The buffer to fill
 * @param off
 *            offset from the buffer
 * @param len
 *            the length of bytes to read
 * @throws IOException
 *             if it could not read requested number of bytes for any reason
 *             (including EOF)
 */
public static void readFileChannelFully(FileChannel fileChannel, byte buf[], int off, int len)
        throws IOException {
    int toRead = len;
    ByteBuffer byteBuffer = ByteBuffer.wrap(buf, off, len);
    while (toRead > 0) {
        int ret = fileChannel.read(byteBuffer);
        if (ret < 0) {
            throw new IOException("Premeture EOF from inputStream");
        }
        toRead -= ret;
        off += ret;
    }
}

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

/**
 * Return the concatenation of the SHA-1 hashes of a file's pieces.
 *
 * <p>/*  www.j  a v  a 2s.  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;
}

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