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:org.alfresco.repo.search.impl.lucene.index.IndexInfo.java

private boolean checkVersion(FileChannel channel) throws IOException {
    if (channel.size() > 0) {
        channel.position(0);/*from   ww  w  .ja v  a2  s  .co  m*/
        ByteBuffer buffer;

        if (useNIOMemoryMapping) {
            MappedByteBuffer mbb = channel.map(MapMode.READ_ONLY, 0, 8);
            mbb.load();
            buffer = mbb;
        } else {
            buffer = ByteBuffer.wrap(new byte[8]);
            channel.read(buffer);
            buffer.position(0);
        }

        buffer.position(0);
        long onDiskVersion = buffer.getLong();
        return (version == onDiskVersion);
    }
    return (version == 0);
}

From source file:org.alfresco.repo.search.impl.lucene.index.IndexInfo.java

private void setStatusFromFile(FileChannel channel) throws IOException {
    if (channel.size() > 0) {
        channel.position(0);/*from   w w w . j  av a2 s .c  o m*/
        ByteBuffer buffer;

        if (useNIOMemoryMapping) {
            MappedByteBuffer mbb = channel.map(MapMode.READ_ONLY, 0, channel.size());
            mbb.load();
            buffer = mbb;
        } else {
            buffer = ByteBuffer.wrap(new byte[(int) channel.size()]);
            channel.read(buffer);
            buffer.position(0);
        }

        buffer.position(0);
        long onDiskVersion = buffer.getLong();
        if (version != onDiskVersion) {
            CRC32 crc32 = new CRC32();
            crc32.update((int) (onDiskVersion >>> 32) & 0xFFFFFFFF);
            crc32.update((int) (onDiskVersion >>> 0) & 0xFFFFFFFF);
            int size = buffer.getInt();
            crc32.update(size);
            LinkedHashMap<String, IndexEntry> newIndexEntries = new LinkedHashMap<String, IndexEntry>();
            // Not all state is saved some is specific to this index so we
            // need to add the transient stuff.
            // Until things are committed they are not shared unless it is
            // prepared
            for (int i = 0; i < size; i++) {
                String indexTypeString = readString(buffer, crc32);
                IndexType indexType;
                try {
                    indexType = IndexType.valueOf(indexTypeString);
                } catch (IllegalArgumentException e) {
                    throw new IOException("Invalid type " + indexTypeString);
                }

                String name = readString(buffer, crc32);

                String parentName = readString(buffer, crc32);

                String txStatus = readString(buffer, crc32);
                TransactionStatus status;
                try {
                    status = TransactionStatus.valueOf(txStatus);
                } catch (IllegalArgumentException e) {
                    throw new IOException("Invalid status " + txStatus);
                }

                String mergeId = readString(buffer, crc32);

                long documentCount = buffer.getLong();
                crc32.update((int) (documentCount >>> 32) & 0xFFFFFFFF);
                crc32.update((int) (documentCount >>> 0) & 0xFFFFFFFF);

                long deletions = buffer.getLong();
                crc32.update((int) (deletions >>> 32) & 0xFFFFFFFF);
                crc32.update((int) (deletions >>> 0) & 0xFFFFFFFF);

                byte deleteOnlyNodesFlag = buffer.get();
                crc32.update(deleteOnlyNodesFlag);
                boolean isDeletOnlyNodes = deleteOnlyNodesFlag == 1;

                if (!status.isTransient()) {
                    newIndexEntries.put(name, new IndexEntry(indexType, name, parentName, status, mergeId,
                            documentCount, deletions, isDeletOnlyNodes));
                }
            }
            long onDiskCRC32 = buffer.getLong();
            if (crc32.getValue() == onDiskCRC32) {
                for (IndexEntry entry : indexEntries.values()) {
                    if (entry.getStatus().isTransient()) {
                        newIndexEntries.put(entry.getName(), entry);
                    }
                }
                version = onDiskVersion;
                indexEntries = newIndexEntries;
            } else {
                throw new IOException("Invalid file check sum");
            }
        }
    }

}

From source file:org.sakaiproject.assignment.tool.AssignmentAction.java

private byte[] readIntoBytes(InputStream zin, String fName, long length) throws IOException {

    byte[] buffer = new byte[4096];

    File f = File.createTempFile("asgnup", "tmp");

    FileOutputStream fout = new FileOutputStream(f);
    try {/* w w  w .j  a  v a  2  s  .  co  m*/
        int len;
        while ((len = zin.read(buffer)) > 0) {
            fout.write(buffer, 0, len);
        }
        zin.close();
    } finally {
        try {
            fout.close(); // The file channel needs to be closed before the deletion.
        } catch (IOException ioException) {
            M_log.warn(this + "readIntoBytes: problem closing FileOutputStream " + ioException.getMessage());
        }
    }

    FileInputStream fis = new FileInputStream(f);
    FileChannel fc = fis.getChannel();
    byte[] data = null;
    try {
        data = new byte[(int) (fc.size())]; // fc.size returns the size of the file which backs the channel
        ByteBuffer bb = ByteBuffer.wrap(data);
        fc.read(bb);
    } finally {
        try {
            fc.close(); // The file channel needs to be closed before the deletion.
        } catch (IOException ioException) {
            M_log.warn(this + "readIntoBytes: problem closing FileChannel " + ioException.getMessage());
        }

        try {
            fis.close(); // The file inputstream needs to be closed before the deletion.
        } catch (IOException ioException) {
            M_log.warn(this + "readIntoBytes: problem closing FileInputStream " + ioException.getMessage());
        }
    }

    //remove the file
    f.delete();

    return data;
}