Example usage for java.nio.channels SeekableByteChannel read

Introduction

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

Prototype

@Override
int read(ByteBuffer dst) throws IOException;

Source Link

Document

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

Usage

From source file:org.cryptomator.crypto.aes256.Aes256Cryptor.java

@Override
public Long decryptRange(SeekableByteChannel encryptedFile, OutputStream plaintextFile, long pos, long length)
        throws IOException {
    // read iv://from  w ww  .java2 s  . c  om
    encryptedFile.position(0);
    final ByteBuffer countingIv = ByteBuffer.allocate(AES_BLOCK_LENGTH);
    final int numIvBytesRead = encryptedFile.read(countingIv);

    // check validity of header:
    if (numIvBytesRead != AES_BLOCK_LENGTH) {
        throw new IOException("Failed to read file header.");
    }

    // seek relevant position and update iv:
    long firstRelevantBlock = pos / AES_BLOCK_LENGTH; // cut of fraction!
    long beginOfFirstRelevantBlock = firstRelevantBlock * AES_BLOCK_LENGTH;
    long offsetInsideFirstRelevantBlock = pos - beginOfFirstRelevantBlock;
    countingIv.putLong(AES_BLOCK_LENGTH - Long.BYTES, firstRelevantBlock);

    // fast forward stream:
    encryptedFile.position(64 + beginOfFirstRelevantBlock);

    // generate cipher:
    final Cipher cipher = this.aesCtrCipher(primaryMasterKey, countingIv.array(), Cipher.DECRYPT_MODE);

    // read content
    final InputStream in = new SeekableByteChannelInputStream(encryptedFile);
    final InputStream cipheredIn = new CipherInputStream(in, cipher);
    return IOUtils.copyLarge(cipheredIn, plaintextFile, offsetInsideFirstRelevantBlock, length);
}

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From source file:org.mycore.common.content.util.MCRServletContentHelper.java

/**
 * Consumes the content and writes it to the ServletOutputStream.
 *
 * @param content  The source resource//w w w.  jav a2s. c om
 * @param out   The outputBufferSize stream to write to
 * @param range     Range the client wanted to retrieve
 */
private static void copy(final MCRContent content, final ServletOutputStream out, final Range range,
        // TODO: beautify this
        final int inputBufferSize, final int outputBufferSize) throws IOException {
    if (content.isReusable()) {
        try (ReadableByteChannel readableByteChannel = content.getReadableByteChannel()) {
            if (readableByteChannel instanceof SeekableByteChannel) {
                endCurrentTransaction();
                SeekableByteChannel seekableByteChannel = (SeekableByteChannel) readableByteChannel;
                seekableByteChannel.position(range.start);
                long bytesToCopy = range.end - range.start + 1;
                while (bytesToCopy > 0) {
                    ByteBuffer byteBuffer;
                    if (bytesToCopy > (long) MCRServletContentHelper.DEFAULT_BUFFER_SIZE) {
                        byteBuffer = ByteBuffer.allocate(MCRServletContentHelper.DEFAULT_BUFFER_SIZE);
                    } else {
                        byteBuffer = ByteBuffer.allocate((int) bytesToCopy);
                    }

                    int bytesRead = seekableByteChannel.read(byteBuffer);
                    bytesToCopy -= bytesRead;
                    out.write(byteBuffer.array());
                }
                return;
            }
        }
    }

    try (final InputStream resourceInputStream = content.getInputStream();
            final InputStream in = isInputStreamBuffered(resourceInputStream, content) ? resourceInputStream
                    : new BufferedInputStream(resourceInputStream, inputBufferSize)) {
        endCurrentTransaction();
        final IOException exception = copyRange(in, out, 0, range.start, range.end, outputBufferSize);
        if (exception != null) {
            throw exception;
        }
    }
}

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