    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.io.file.spi;
    019
    020import java.net.URI;
    021import java.net.URL;
    022import java.nio.file.FileSystems;
    023import java.nio.file.Path;
    024import java.nio.file.spi.FileSystemProvider;
    025import java.util.List;
    026import java.util.Objects;
    027
    028/**
    029 * Helps working with {@link FileSystemProvider}.
    030 *
    031 * @since 2.9.0
    032 */
    033public class FileSystemProviders {
    034
    035    private static final FileSystemProviders INSTALLED = new FileSystemProviders(FileSystemProvider.installedProviders());
    036
    037    /**
    038     * Gets the {@link FileSystemProvider} for the given Path.
    039     *
    040     * @param path The Path to query
    041     * @return the {@link FileSystemProvider} for the given Path.
    042     */
    043    @SuppressWarnings("resource") // FileSystem is not allocated here.
    044    public static FileSystemProvider getFileSystemProvider(final Path path) {
    045        return Objects.requireNonNull(path, "path").getFileSystem().provider();
    046    }
    047
    048    /**
    049     * Returns the instance for the installed providers.
    050     *
    051     * @return the instance for the installed providers.
    052     * @see FileSystemProvider#installedProviders()
    053     */
    054    public static FileSystemProviders installed() {
    055        return INSTALLED;
    056    }
    057
    058    private final List<FileSystemProvider> providers;
    059
    060    /*
    061     * Might make public later.
    062     */
    063    private FileSystemProviders(final List<FileSystemProvider> providers) {
    064        this.providers = providers;
    065    }
    066
    067    /**
    068     * Gets the {@link FileSystemProvider} for the given scheme.
    069     *
    070     * @param scheme The scheme to query.
    071     * @return the {@link FileSystemProvider} for the given URI or null.
    072     */
    073    @SuppressWarnings("resource") // FileSystems.getDefault() returns a constant.
    074    public FileSystemProvider getFileSystemProvider(final String scheme) {
    075        Objects.requireNonNull(scheme, "scheme");
    076        // Check default provider first to avoid loading of installed providers.
    077        if (scheme.equalsIgnoreCase("file")) {
    078            return FileSystems.getDefault().provider();
    079        }
    080        // Find provider.
    081        if (providers != null) {
    082            for (final FileSystemProvider provider : providers) {
    083                if (provider.getScheme().equalsIgnoreCase(scheme)) {
    084                    return provider;
    085                }
    086            }
    087        }
    088        return null;
    089    }
    090
    091    /**
    092     * Gets the {@link FileSystemProvider} for the given URI.
    093     *
    094     * @param uri The URI to query
    095     * @return the {@link FileSystemProvider} for the given URI or null.
    096     */
    097    public FileSystemProvider getFileSystemProvider(final URI uri) {
    098        return getFileSystemProvider(Objects.requireNonNull(uri, "uri").getScheme());
    099    }
    100
    101    /**
    102     * Gets the {@link FileSystemProvider} for the given URL.
    103     *
    104     * @param url The URL to query
    105     * @return the {@link FileSystemProvider} for the given URI or null.
    106     */
    107    public FileSystemProvider getFileSystemProvider(final URL url) {
    108        return getFileSystemProvider(Objects.requireNonNull(url, "url").getProtocol());
    109    }
    110
    111}