DefaultFileRegion Class — netty Architecture

Source Code

transport/src/main/java/io/netty/channel/DefaultFileRegion.java lines 38–192

public class DefaultFileRegion extends AbstractReferenceCounted implements FileRegion {

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(DefaultFileRegion.class);
    private final File f;
    private final long position;
    private final long count;
    private long transferred;
    private FileChannel file;

    /**
     * Create a new instance
     *
     * @param fileChannel      the {@link FileChannel} which should be transferred
     * @param position         the position from which the transfer should start
     * @param count            the number of bytes to transfer
     */
    public DefaultFileRegion(FileChannel fileChannel, long position, long count) {
        this.file = ObjectUtil.checkNotNull(fileChannel, "fileChannel");
        this.position = checkPositiveOrZero(position, "position");
        this.count = checkPositiveOrZero(count, "count");
        this.f = null;
    }

    /**
     * Create a new instance using the given {@link File}. The {@link File} will be opened lazily or
     * explicitly via {@link #open()}.
     *
     * @param file         the {@link File} which should be transferred
     * @param position     the position from which the transfer should start
     * @param count        the number of bytes to transfer
     */
    public DefaultFileRegion(File file, long position, long count) {
        this.f = ObjectUtil.checkNotNull(file, "file");
        this.position = checkPositiveOrZero(position, "position");
        this.count = checkPositiveOrZero(count, "count");
    }

    /**
     * Returns {@code true} if the {@link FileRegion} has a open file-descriptor
     */
    public boolean isOpen() {
        return file != null;
    }

    /**
     * Explicitly open the underlying file-descriptor if not done yet.
     */
    public void open() throws IOException {
        if (!isOpen() && refCnt() > 0) {
            // Only open if this DefaultFileRegion was not released yet.
            file = new RandomAccessFile(f, "r").getChannel();
        }
    }

    @Override
    public long position() {
        return position;
    }

    @Override
    public long count() {
        return count;
    }

    @Deprecated
    @Override
    public long transfered() {
        return transferred;
    }

    @Override
    public long transferred() {
        return transferred;
    }

    @Override
    public long transferTo(WritableByteChannel target, long position) throws IOException {
        long count = this.count - position;
        if (count < 0 || position < 0) {
            throw new IllegalArgumentException(
                    "position out of range: " + position +