Examples with WarningListeners org.apache.sis.util.logging.WarningListeners used on opensource projects

Example 1 with WarningListeners

use of org.apache.sis.util.logging.WarningListeners in project sis by apache.

the class ChannelFactory method prepare.

/**
 * Returns a byte channel factory from the given input or output,
 * or {@code null} if the given input/output is of unknown type.
 * More specifically:
 *
 * <ul>
 *   <li>If the given storage is {@code null}, then this method returns {@code null}.</li>
 *   <li>If the given storage is a {@link ReadableByteChannel} or an {@link InputStream},
 *       then the factory will return that input directly or indirectly as a wrapper.</li>
 *   <li>If the given storage is a {@link WritableByteChannel} or an {@link OutputStream}
 *       and the {@code allowWriteOnly} argument is {@code true},
 *       then the factory will return that output directly or indirectly as a wrapper.</li>
 *   <li>If the given storage if a {@link Path}, {@link File}, {@link URL}, {@link URI}
 *       or {@link CharSequence}, then the factory will open new channels on demand.</li>
 * </ul>
 *
 * The given options are used for opening the channel on a <em>best effort basis</em>.
 * In particular, even if the caller provided the {@code WRITE} option, he still needs
 * to verify if the returned channel implements {@link java.nio.channels.WritableByteChannel}.
 * This is because the channel may be opened by {@link URL#openStream()}, in which case the
 * options are ignored.
 *
 * <p>The following options are illegal for read operations and will cause an exception to be
 * thrown if provided while {@code allowWriteOnly} is {@code false}:
 * {@code APPEND}, {@code TRUNCATE_EXISTING}, {@code DELETE_ON_CLOSE}. We reject those options
 * because this method is primarily designed for readable channels, with optional data edition.
 * Since the write option is not guaranteed to be honored, we have to reject the options that
 * would alter significatively the channel behavior depending on whether we have been able to
 * honor the options or not.</p>
 *
 * @param  storage         the stream or the file to open, or {@code null}.
 * @param  encoding        if the input is an encoded URL, the character encoding (normally {@code "UTF-8"}).
 *                         If the URL is not encoded, then {@code null}. This argument is ignored if the given
 *                         input does not need to be converted from URL to {@code File}.
 * @param  allowWriteOnly  whether to allow wrapping {@link WritableByteChannel} and {@link OutputStream}.
 * @param  options         the options to use for creating a new byte channel. Can be null or empty for read-only.
 * @return the channel factory for the given input, or {@code null} if the given input is of unknown type.
 * @throws IOException if an error occurred while processing the given input.
 */
public static ChannelFactory prepare(Object storage, final String encoding, final boolean allowWriteOnly, OpenOption... options) throws IOException {
    /*
         * Unconditionally verify the options (unless 'allowWriteOnly' is true),
         * even if we may not use them.
         */
    final Set<OpenOption> optionSet;
    if (options == null || options.length == 0) {
        optionSet = Collections.singleton(StandardOpenOption.READ);
    } else {
        optionSet = new HashSet<>(Arrays.asList(options));
        optionSet.add(StandardOpenOption.READ);
        if (!allowWriteOnly && optionSet.removeAll(ILLEGAL_OPTIONS)) {
            throw new IllegalArgumentException(Errors.format(Errors.Keys.IllegalArgumentValue_2, "options", Arrays.toString(options)));
        }
    }
    /*
         * Check for inputs that are already readable channels or input streams.
         * Note that Channels.newChannel(InputStream) checks for instances of FileInputStream in order to delegate
         * to its getChannel() method, but only if the input stream type is exactly FileInputStream, not a subtype.
         * If Apache SIS defines its own FileInputStream subclass someday, we may need to add a special case here.
         */
    if (storage instanceof ReadableByteChannel || (allowWriteOnly && storage instanceof WritableByteChannel)) {
        return new Stream((Channel) storage);
    } else if (storage instanceof InputStream) {
        return new Stream(Channels.newChannel((InputStream) storage));
    } else if (allowWriteOnly && storage instanceof OutputStream) {
        return new Stream(Channels.newChannel((OutputStream) storage));
    }
    /*
         * In the following cases, we will try hard to convert to Path objects before to fallback
         * on File, URL or URI, because only Path instances allow us to use the given OpenOptions.
         */
    if (storage instanceof URL) {
        try {
            storage = IOUtilities.toPath((URL) storage, encoding);
        } catch (IOException e) {
            /*
                 * This is normal if the URL uses HTTP or FTP protocol for instance. Log the exception at FINE
                 * level without stack trace. We will open the channel later using the URL instead than the Path.
                 */
            recoverableException(e);
        }
    } else if (storage instanceof URI) {
        /*
             * If the user gave us a URI, try to convert to a Path before to fallback to URL, in order to be
             * able to use the given OpenOptions.  Note that the conversion to Path is likely to fail if the
             * URL uses HTTP or FTP protocols, because JDK7 does not provide file systems for them by default.
             */
        final URI uri = (URI) storage;
        if (!uri.isAbsolute()) {
            /*
                 * All methods invoked in this block throws IllegalArgumentException if the URI has no scheme,
                 * so we are better to check now and provide a more appropriate exception for this method.
                 */
            throw new IOException(Resources.format(Resources.Keys.MissingSchemeInURI_1, uri));
        } else
            try {
                storage = Paths.get(uri);
            } catch (IllegalArgumentException | FileSystemNotFoundException e) {
                try {
                    storage = uri.toURL();
                } catch (MalformedURLException ioe) {
                    ioe.addSuppressed(e);
                    throw ioe;
                }
                /*
                 * We have been able to convert to URL, but the given OpenOptions may not be used.
                 * Log the exception at FINE level without stack trace, because the exception is
                 * probably a normal behavior in this context.
                 */
                recoverableException(e);
            }
    } else {
        if (storage instanceof CharSequence) {
            // Needs to be before the check for File or URL.
            storage = IOUtilities.toFileOrURL(storage.toString(), encoding);
        }
        /*
             * If the input is a File or a CharSequence that we have been able to convert to a File,
             * try to convert to a Path in order to be able to use the OpenOptions. Only if we fail
             * to convert to a Path (which is unlikely), we will use directly the File.
             */
        if (storage instanceof File) {
            final File file = (File) storage;
            try {
                storage = file.toPath();
            } catch (final InvalidPathException e) {
                /*
                     * Unlikely to happen. But if it happens anyway, try to open the channel in a
                     * way less surprising for the user (closer to the object he has specified).
                     */
                if (file.isFile()) {
                    return new Fallback(file, e);
                }
            }
        }
    }
    /*
         * One last check for URL. The URL may be either the given input if we have not been able
         * to convert it to a Path, or a URI, File or CharSequence input converted to URL. Do not
         * try to convert the URL to a Path, because this has already been tried before this point.
         */
    if (storage instanceof URL) {
        final URL file = (URL) storage;
        return new ChannelFactory() {

            @Override
            public ReadableByteChannel readable(String filename, WarningListeners<DataStore> listeners) throws IOException {
                return Channels.newChannel(file.openStream());
            }

            @Override
            public WritableByteChannel writable(String filename, WarningListeners<DataStore> listeners) throws IOException {
                return Channels.newChannel(file.openConnection().getOutputStream());
            }
        };
    }
    if (storage instanceof Path) {
        final Path path = (Path) storage;
        if (Files.isRegularFile(path)) {
            return new ChannelFactory() {

                @Override
                public ReadableByteChannel readable(String filename, WarningListeners<DataStore> listeners) throws IOException {
                    return Files.newByteChannel(path, optionSet);
                }

                @Override
                public WritableByteChannel writable(String filename, WarningListeners<DataStore> listeners) throws IOException {
                    return Files.newByteChannel(path, optionSet);
                }
            };
        }
    }
    return null;
}