Example usage for java.nio.channels FileChannel read

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

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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:no.sesat.search.http.filters.SiteJspLoaderFilter.java

private void downloadJsp(final HttpServletRequest request, final String jsp) throws MalformedURLException {

    final StopWatch stopWatch = new StopWatch();
    stopWatch.start();//w  w  w  .  ja v a 2s .  com

    byte[] golden = new byte[0];

    // search skins for the jsp and write it out to "golden"
    for (Site site = (Site) request.getAttribute(Site.NAME_KEY); 0 == golden.length; site = site.getParent()) {

        if (null == site) {
            if (null == config.getServletContext().getResource(jsp)) {
                throw new ResourceLoadException("Unable to find " + jsp + " in any skin");
            }
            break;
        }

        final Site finalSite = site;
        final BytecodeLoader bcLoader = UrlResourceLoader.newBytecodeLoader(finalSite.getSiteContext(), jsp,
                null);
        bcLoader.abut();
        golden = bcLoader.getBytecode();
    }

    // if golden now contains data save it to a local (ie local web application) file
    if (0 < golden.length) {
        try {
            final File file = new File(root + jsp);

            // create the directory structure
            file.getParentFile().mkdirs();

            // check existing file
            boolean needsUpdating = true;
            final boolean fileExisted = file.exists();
            if (!fileExisted) {
                file.createNewFile();
            }

            // channel.lock() only synchronises file access between programs, but not between threads inside
            //  the current JVM. The latter results in the OverlappingFileLockException.
            //  At least this is my current understanding of java.nio.channels
            //   It may be that no synchronisation or locking is required at all. A beer to whom answers :-)
            // So we must provide synchronisation between our own threads,
            //  synchronisation against the file's path (using the JVM's String.intern() functionality)
            //  should work. (I can't imagine this string be used for any other synchronisation purposes).
            synchronized (file.toString().intern()) {

                RandomAccessFile fileAccess = null;
                FileChannel channel = null;

                try {

                    fileAccess = new RandomAccessFile(file, "rws");
                    channel = fileAccess.getChannel();

                    channel.lock();

                    if (fileExisted) {

                        final byte[] bytes = new byte[(int) channel.size()];
                        final ByteBuffer byteBuffer = ByteBuffer.wrap(bytes);
                        int reads;
                        do {
                            reads = channel.read(byteBuffer);
                        } while (0 < reads);

                        needsUpdating = !Arrays.equals(golden, bytes);
                    }

                    if (needsUpdating) {
                        // download file from skin
                        channel.write(ByteBuffer.wrap(golden), 0);
                        file.deleteOnExit();
                    }
                } finally {
                    if (null != channel) {
                        channel.close();
                    }
                    if (null != fileAccess) {
                        fileAccess.close();
                    }

                    LOG.debug("resource created as " + config.getServletContext().getResource(jsp));
                }
            }

        } catch (IOException ex) {
            LOG.error(ex.getMessage(), ex);
        }
    }

    stopWatch.stop();
    LOG.trace("SiteJspLoaderFilter.downloadJsp(..) took " + stopWatch);
}

From source file:org.neo4j.io.pagecache.impl.SingleFilePageSwapper.java

private long lockPositionReadVector(long filePageId, FileChannel channel, long fileOffset, ByteBuffer[] srcs)
        throws IOException {
    try {//from w  ww . j  av a  2s. c  o  m
        long toRead = filePageSize * (long) srcs.length;
        long read, readTotal = 0;
        synchronized (positionLock(channel)) {
            channel.position(fileOffset);
            do {
                read = channel.read(srcs);
            } while (read != -1 && (readTotal += read) < toRead);
            return readTotal;
        }
    } catch (ClosedChannelException e) {
        // AsynchronousCloseException is a subclass of
        // ClosedChannelException, and ClosedByInterruptException is in
        // turn a subclass of AsynchronousCloseException.
        tryReopen(filePageId, e);
        boolean interrupted = Thread.interrupted();
        // Recurse because this is hopefully a very rare occurrence.
        channel = unwrappedChannel(filePageId);
        long bytesWritten = lockPositionReadVector(filePageId, channel, fileOffset, srcs);
        if (interrupted) {
            Thread.currentThread().interrupt();
        }
        return bytesWritten;
    }
}

From source file:eu.stratosphere.nephele.taskmanager.runtime.EnvelopeConsumptionLog.java

private void loadNextOutstandingEnvelopes() {

    final int pos = this.outstandingEnvelopesAsIntBuffer.position();

    if (pos > 0) {

        final int rem = this.outstandingEnvelopesAsIntBuffer.remaining();

        for (int i = 0; i < rem; ++i) {
            this.outstandingEnvelopesAsIntBuffer.put(i, this.outstandingEnvelopesAsIntBuffer.get(i + pos));
        }//from   w  w  w  .  ja v a2s . co m

        this.outstandingEnvelopesAsIntBuffer.position(0);
        this.outstandingEnvelopesAsIntBuffer.limit(rem);
    }

    if (this.numberOfEntriesReadFromLog == this.numberOfInitialLogEntries) {
        return;
    }

    FileChannel fc = null;

    try {

        this.outstandingEnvelopesAsByteBuffer
                .position(this.outstandingEnvelopesAsIntBuffer.limit() * SIZE_OF_INTEGER);
        this.outstandingEnvelopesAsByteBuffer.limit(this.outstandingEnvelopesAsByteBuffer.capacity());

        fc = new FileInputStream(this.logFile).getChannel();
        fc.position(this.numberOfEntriesReadFromLog * SIZE_OF_INTEGER);

        int totalBytesRead = 0;

        while (this.outstandingEnvelopesAsByteBuffer.hasRemaining()) {

            final int bytesRead = fc.read(this.outstandingEnvelopesAsByteBuffer);
            if (bytesRead == -1) {
                break;
            }

            totalBytesRead += bytesRead;
        }

        if (totalBytesRead % SIZE_OF_INTEGER != 0) {
            LOG.error("Read " + totalBytesRead + " from " + this.logFile.getAbsolutePath()
                    + ", file may be corrupt");
        }

        final int numberOfNewEntries = totalBytesRead / SIZE_OF_INTEGER;

        this.outstandingEnvelopesAsIntBuffer
                .limit(this.outstandingEnvelopesAsIntBuffer.limit() + numberOfNewEntries);

        this.numberOfEntriesReadFromLog += numberOfNewEntries;

        fc.close();

    } catch (IOException ioe) {
        LOG.error(StringUtils.stringifyException(ioe));
    } finally {

        if (fc != null) {
            try {
                fc.close();
            } catch (IOException ioe) {
            }
        }
    }
}

From source file:dk.statsbiblioteket.util.LineReaderTest.java

public void testNIO() throws Exception {
    byte[] INITIAL = new byte[] { 1, 2, 3, 4 };
    byte[] EXTRA = new byte[] { 5, 6, 7, 8 };
    byte[] FULL = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
    byte[] FIFTH = new byte[] { 87 };
    byte[] FULL_WITH_FIFTH = new byte[] { 1, 2, 3, 4, 87, 6, 7, 8 };

    // Create temp-file with content
    File temp = createTempFile();
    FileOutputStream fileOut = new FileOutputStream(temp, true);
    fileOut.write(INITIAL);//from   w  w w .j ava2  s  .c o  m
    fileOut.close();

    checkContent("The plain test-file should be correct", temp, INITIAL);
    {
        // Read the 4 bytes
        RandomAccessFile input = new RandomAccessFile(temp, "r");
        FileChannel channelIn = input.getChannel();
        ByteBuffer buffer = ByteBuffer.allocate(4096);
        channelIn.position(0);
        assertEquals("Buffer read should read full length", INITIAL.length, channelIn.read(buffer));
        buffer.position(0);

        checkContent("Using buffer should produce the right bytes", INITIAL, buffer);
        channelIn.close();
        input.close();
    }
    {
        // Fill new buffer
        ByteBuffer outBuffer = ByteBuffer.allocate(4096);
        outBuffer.put(EXTRA);
        outBuffer.flip();
        assertEquals("The limit of the outBuffer should be correct", EXTRA.length, outBuffer.limit());

        // Append new buffer to end
        RandomAccessFile output = new RandomAccessFile(temp, "rw");
        FileChannel channelOut = output.getChannel();
        channelOut.position(INITIAL.length);
        assertEquals("All bytes should be written", EXTRA.length, channelOut.write(outBuffer));
        channelOut.close();
        output.close();
        checkContent("The resulting file should have the full output", temp, FULL);
    }

    {
        // Fill single byte buffer
        ByteBuffer outBuffer2 = ByteBuffer.allocate(4096);
        outBuffer2.put(FIFTH);
        outBuffer2.flip();
        assertEquals("The limit of the second outBuffer should be correct", FIFTH.length, outBuffer2.limit());

        // Insert byte in the middle
        RandomAccessFile output2 = new RandomAccessFile(temp, "rw");
        FileChannel channelOut2 = output2.getChannel();
        channelOut2.position(4);
        assertEquals("The FIFTH should be written", FIFTH.length, channelOut2.write(outBuffer2));
        channelOut2.close();
        output2.close();
        checkContent("The resulting file with fifth should be complete", temp, FULL_WITH_FIFTH);
    }
}

From source file:com.yobidrive.diskmap.buckets.BucketTableManager.java

private void initializeBucketTableFromLastCommittedBucketFile() throws BucketTableManagerException {
    FileInputStream tableStream = null;
    FileChannel fileChannel = null;
    try {//from   w ww .  j  av  a  2 s. com
        File latestCommittedFile = getLatestCommitedFile();
        if (latestCommittedFile != null) {
            tableStream = new FileInputStream(latestCommittedFile);
            fileChannel = tableStream.getChannel();
            ByteBuffer buffer = ByteBuffer.allocate(HEADERSIZE);
            fileChannel.position(0L);
            int read = fileChannel.read(buffer);
            if (read < HEADERSIZE) {
                fileChannel.close();
                throw new BucketTableManagerException(
                        "Wrong bucket table header size: " + read + "/" + HEADERSIZE);
            }
            // Check content of header. Start with Big Endian (default for Java)
            buffer.rewind();
            byteOrder = ByteOrder.BIG_ENDIAN;
            buffer.order(byteOrder);
            int magic = buffer.getInt();
            if (magic == MAGICSTART_BADENDIAN) {
                byteOrder = ByteOrder.LITTLE_ENDIAN;
                buffer.order(byteOrder);
            } else if (magic != MAGICSTART) {
                fileChannel.close();
                throw new BucketTableManagerException("Bad header in bucket table file");
            }
            // Read number of buckets
            long headerMapSize = buffer.getLong();
            // Read checkPoint
            NeedlePointer includedCheckpoint = new NeedlePointer();
            includedCheckpoint.getNeedlePointerFromBuffer(buffer);
            // Read second magic number
            magic = buffer.getInt();
            if (magic != MAGICEND) {
                fileChannel.close();
                throw new BucketTableManagerException("Bad header in bucket table file");
            }
            // Check number of buckets against requested map size
            if (headerMapSize != mapSize) {
                // Map size does not match
                fileChannel.close();
                throw new BucketTableManagerException(
                        "Requested map size " + mapSize + " does not match header map size " + headerMapSize);
            }
            // Sets initial checkpoint
            bucketTable.setInitialCheckPoint(includedCheckpoint);
            // Now reads all entries
            logger.info("Hot start: loading buckets...");
            for (int i = 0; i < nbBuffers; i++) {
                bucketTable.prepareBufferForReading(i);
                read = fileChannel.read(bucketTable.getBuffer(i));
                if (read < bucketTable.getBuffer(i).limit())
                    throw new BucketTableManagerException("Incomplete bucket table file "
                            + latestCommittedFile.getName() + ", expected " + mapSize + HEADERSIZE);
                //else
                //   logger.info("Hot start: loaded "+(i+1)*entriesPerBuffer+" buckets"+((i<(nbBuffers-1))?"...":"")) ;
            }
            // Checks second magic marker
            buffer = ByteBuffer.allocate(NeedleLogInfo.INFOSIZE);
            buffer.rewind();
            buffer.limit(INTSIZE);
            if (fileChannel.read(buffer) < INTSIZE)
                throw new BucketTableManagerException(
                        "Incomplete bucket table file, missing secong magic number "
                                + latestCommittedFile.getName());
            buffer.rewind();
            magic = buffer.getInt();
            if (magic != MAGICSTART) {
                fileChannel.close();
                throw new BucketTableManagerException("Bad header in bucket table file");
            }
            // Now reads clean counters
            while (true) {
                buffer.rewind();
                buffer.limit(NeedleLogInfo.INFOSIZE);
                read = fileChannel.read(buffer);
                if (read > 0 && read < NeedleLogInfo.INFOSIZE)
                    throw new BucketTableManagerException("Incomplete bucket table file, log info too short "
                            + latestCommittedFile.getName() + ", expected " + mapSize + HEADERSIZE);
                if (read <= 0)
                    break;
                else {
                    NeedleLogInfo nli = new NeedleLogInfo(useAverage);
                    buffer.rewind();
                    nli.getNeedleLogInfo(buffer);
                    logInfoPerLogNumber.put(new Integer(nli.getNeedleFileNumber()), nli);
                }
            }
            logger.info("Hot start: loaded " + (nbBuffers * entriesPerBuffer) + " buckets");

        } else {
            // Empty file
            bucketTable.setInitialCheckPoint(new NeedlePointer());
            bucketTable.format();
        }
    } catch (IOException ie) {
        throw new BucketTableManagerException("Failed initializing bucket table", ie);
    } catch (BufferUnderflowException bue) {
        throw new BucketTableManagerException("Bucket table too short", bue);
    } finally {
        if (fileChannel != null) {
            try {
                fileChannel.close();
            } catch (IOException ex) {
                throw new BucketTableManagerException("Error while closing file channel", ex);
            }
        }
    }
}

From source file:org.alfresco.repo.content.AbstractWritableContentStoreTest.java

/**
 * Tests random access reading//  w  w  w  .ja va  2  s .co  m
 * <p>
 * Only executes if the reader implements {@link RandomAccessContent}.
 */
@Test
public void testRandomAccessRead() throws Exception {
    ContentWriter writer = getWriter();
    // put some content
    String content = "ABC";
    byte[] bytes = content.getBytes();
    writer.putContent(content);
    ContentReader reader = writer.getReader();

    FileChannel fileChannel = reader.getFileChannel();
    assertNotNull("No channel given", fileChannel);

    // check that no other content access is allowed
    try {
        reader.getReadableChannel();
        fail("Second channel access allowed");
    } catch (RuntimeException e) {
        // expected
    }

    // read the content
    ByteBuffer buffer = ByteBuffer.allocate(bytes.length);
    int count = fileChannel.read(buffer);
    assertEquals("Incorrect number of bytes read", bytes.length, count);
    // transfer back to array
    buffer.rewind();
    buffer.get(bytes);
    String checkContent = new String(bytes);
    assertEquals("Content read failure", content, checkContent);
    fileChannel.close();
}

From source file:com.liferay.portal.util.FileImpl.java

public boolean isSameContent(File file, byte[] bytes, int length) {
    FileChannel fileChannel = null;

    try {//w  w  w.j av  a2s . c o  m
        FileInputStream fileInputStream = new FileInputStream(file);

        fileChannel = fileInputStream.getChannel();

        if (fileChannel.size() != length) {
            return false;
        }

        byte[] buffer = new byte[1024];

        ByteBuffer byteBuffer = ByteBuffer.wrap(buffer);

        int bufferIndex = 0;
        int bufferLength = -1;

        while (((bufferLength = fileChannel.read(byteBuffer)) > 0) && (bufferIndex < length)) {

            for (int i = 0; i < bufferLength; i++) {
                if (buffer[i] != bytes[bufferIndex++]) {
                    return false;
                }
            }

            byteBuffer.clear();
        }

        if ((bufferIndex != length) || (bufferLength != -1)) {
            return false;
        } else {
            return true;
        }
    } catch (Exception e) {
        return false;
    } finally {
        if (fileChannel != null) {
            try {
                fileChannel.close();
            } catch (IOException ioe) {
            }
        }
    }
}

From source file:com.colorchen.qbase.utils.FileUtil.java

/**
 * ?/*from  www.  j a v a  2 s.c o  m*/
 *
 * @param outFile
 * @param files
 */
public static void mergeFiles(Context context, File outFile, List<File> files) {
    FileChannel outChannel = null;
    try {
        outChannel = new FileOutputStream(outFile).getChannel();
        for (File f : files) {
            FileChannel fc = new FileInputStream(f).getChannel();
            ByteBuffer bb = ByteBuffer.allocate(BUFSIZE);
            while (fc.read(bb) != -1) {
                bb.flip();
                outChannel.write(bb);
                bb.clear();
            }
            fc.close();
        }
        Log.d(TAG, "?");
    } catch (IOException ioe) {
        ioe.printStackTrace();
    } finally {
        try {
            if (outChannel != null) {
                outChannel.close();
            }
        } catch (IOException ignore) {
        }
    }
}

From source file:org.carbondata.query.aggregator.impl.CustomAggregatorHelper.java

/**
 * Below method will be used to read the level files
 *
 * @param memberFile/*from w w  w  .  j  a v a2 s  . c  o m*/
 * @param fileName
 * @throws IOException
 */
private void readLevelFileAndUpdateCache(File memberFile, String fileName) throws IOException {
    FileInputStream fos = null;
    FileChannel fileChannel = null;
    try {
        // create an object of FileOutputStream
        fos = new FileInputStream(memberFile);

        fileChannel = fos.getChannel();
        Map<Integer, String> memberMap = surrogateKeyMap.get(fileName);

        if (null == memberMap) {
            memberMap = new HashMap<Integer, String>(CarbonCommonConstants.DEFAULT_COLLECTION_SIZE);
            surrogateKeyMap.put(fileName, memberMap);
        }

        long size = fileChannel.size();
        int maxKey = 0;
        ByteBuffer rowlengthToRead = null;
        int len = 0;
        ByteBuffer row = null;
        int toread = 0;
        byte[] bb = null;
        String value = null;
        int surrogateValue = 0;

        boolean enableEncoding = Boolean.valueOf(
                CarbonProperties.getInstance().getProperty(CarbonCommonConstants.ENABLE_BASE64_ENCODING,
                        CarbonCommonConstants.ENABLE_BASE64_ENCODING_DEFAULT));

        while (fileChannel.position() < size) {
            rowlengthToRead = ByteBuffer.allocate(4);
            fileChannel.read(rowlengthToRead);
            rowlengthToRead.rewind();
            len = rowlengthToRead.getInt();
            if (len == 0) {
                continue;
            }

            row = ByteBuffer.allocate(len);
            fileChannel.read(row);
            row.rewind();
            toread = row.getInt();
            bb = new byte[toread];
            row.get(bb);

            if (enableEncoding) {
                value = new String(Base64.decodeBase64(bb), Charset.defaultCharset());
            } else {
                value = new String(bb, Charset.defaultCharset());
            }

            surrogateValue = row.getInt();
            memberMap.put(surrogateValue, value);

            // check if max key is less than Surrogate key then update the max key
            if (maxKey < surrogateValue) {
                maxKey = surrogateValue;
            }
        }

    } finally {
        CarbonUtil.closeStreams(fileChannel, fos);
    }
}

From source file:org.apache.hadoop.yarn.server.nodemanager.containermanager.TestContainerManager.java

private ByteBuffer readFileToByteBuffer(File source) throws IOException {
    ByteBuffer buffer = ByteBuffer.allocate(128);
    FileChannel fileChannel = new FileInputStream(source).getChannel();
    fileChannel.read(buffer);
    fileChannel.close();//from  www  . j  a v a  2 s  .  c  om
    buffer.flip();
    return buffer;
}