Examples with ChannelFactory org.apache.sis.internal.storage.io.ChannelFactory used on opensource projects

Example 1 with ChannelFactory

use of org.apache.sis.internal.storage.io.ChannelFactory in project sis by apache.

the class StorageConnector method createChannelDataInput.

/**
 * Creates a view for the input as a {@link ChannelDataInput} if possible.
 * This is also a starting point for {@link #createDataInput()} and {@link #createByteBuffer()}.
 * This method is one of the {@link #OPENERS} methods and should be invoked at most once per
 * {@code StorageConnector} instance.
 *
 * @param  asImageInputStream  whether the {@code ChannelDataInput} needs to be {@link ChannelImageInputStream} subclass.
 * @throws IOException if an error occurred while opening a channel for the input.
 */
private ChannelDataInput createChannelDataInput(final boolean asImageInputStream) throws IOException, DataStoreException {
    /*
         * Before to try to wrap an InputStream, mark its position so we can rewind if the user asks for
         * the InputStream directly. We need to reset because ChannelDataInput may have read some bytes.
         * Note that if mark is unsupported, the default InputStream.mark(…) implementation does nothing.
         */
    reset();
    if (storage instanceof InputStream) {
        ((InputStream) storage).mark(DEFAULT_BUFFER_SIZE);
    }
    /*
         * Following method call recognizes ReadableByteChannel, InputStream (with special case for FileInputStream),
         * URL, URI, File, Path or other types that may be added in future Apache SIS versions.
         * If the given storage is already a ReadableByteChannel, then the factory will return it as-is.
         */
    final ChannelFactory factory = ChannelFactory.prepare(storage, getOption(OptionKey.URL_ENCODING), false, getOption(OptionKey.OPEN_OPTIONS));
    if (factory == null) {
        return null;
    }
    /*
         * ChannelDataInput depends on ReadableByteChannel, which itself depends on storage
         * (potentially an InputStream). We need to remember this chain in 'Coupled' objects.
         */
    final String name = getStorageName();
    final ReadableByteChannel channel = factory.readable(name, null);
    addView(ReadableByteChannel.class, channel, null, factory.isCoupled() ? CASCADE_ON_RESET : 0);
    // User-supplied buffer.
    ByteBuffer buffer = getOption(OptionKey.BYTE_BUFFER);
    if (buffer == null) {
        // Default buffer if user did not specified any.
        buffer = ByteBuffer.allocate(DEFAULT_BUFFER_SIZE);
    }
    final ChannelDataInput asDataInput;
    if (asImageInputStream) {
        asDataInput = new ChannelImageInputStream(name, channel, buffer, false);
    } else {
        asDataInput = new ChannelDataInput(name, channel, buffer, false);
    }
    addView(ChannelDataInput.class, asDataInput, ReadableByteChannel.class, CASCADE_ON_RESET);
    /*
         * Following is an undocumented mechanism for allowing some Apache SIS implementations of DataStore
         * to re-open the same channel or input stream another time, typically for re-reading the same data.
         */
    if (factory.canOpen()) {
        addView(ChannelFactory.class, factory);
    }
    return asDataInput;
}