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.Collections;
026import java.util.List;
027import java.util.Objects;
028
029/**
030 * Helps to work with {@link FileSystemProvider}.
031 *
032 * @since 2.9.0
033 */
034public class FileSystemProviders { // NOPMD Class will be final in 3.0.
035
036    private static final String SCHEME_FILE = "file";
037    private static final FileSystemProviders INSTALLED = new FileSystemProviders(FileSystemProvider.installedProviders());
038
039    /**
040     * Gets the {@link FileSystemProvider} for the given Path.
041     *
042     * @param path The Path to query
043     * @return the {@link FileSystemProvider} for the given Path.
044     */
045    @SuppressWarnings("resource") // FileSystem is not allocated here.
046    public static FileSystemProvider getFileSystemProvider(final Path path) {
047        return Objects.requireNonNull(path, "path").getFileSystem().provider();
048    }
049
050    /**
051     * Returns the instance for the installed providers.
052     *
053     * @return the instance for the installed providers.
054     * @see FileSystemProvider#installedProviders()
055     */
056    public static FileSystemProviders installed() {
057        return INSTALLED;
058    }
059
060    private final List<FileSystemProvider> providers;
061
062    /*
063     * Might make public later.
064     */
065    private FileSystemProviders(final List<FileSystemProvider> providers) {
066        this.providers = providers != null ? providers : Collections.emptyList();
067    }
068
069    /**
070     * Gets the {@link FileSystemProvider} for the given scheme.
071     *
072     * @param scheme The scheme to query.
073     * @return the {@link FileSystemProvider} for the given URI or null.
074     */
075    @SuppressWarnings("resource") // FileSystems.getDefault() returns a constant.
076    public FileSystemProvider getFileSystemProvider(final String scheme) {
077        Objects.requireNonNull(scheme, "scheme");
078        // Check default provider first to avoid loading of installed providers.
079        if (scheme.equalsIgnoreCase(SCHEME_FILE)) {
080            return FileSystems.getDefault().provider();
081        }
082        // Find provider.
083        return providers.stream().filter(provider -> provider.getScheme().equalsIgnoreCase(scheme)).findFirst().orElse(null);
084    }
085
086    /**
087     * Gets the {@link FileSystemProvider} for the given URI.
088     *
089     * @param uri The URI to query
090     * @return the {@link FileSystemProvider} for the given URI or null.
091     */
092    public FileSystemProvider getFileSystemProvider(final URI uri) {
093        return getFileSystemProvider(Objects.requireNonNull(uri, "uri").getScheme());
094    }
095
096    /**
097     * Gets the {@link FileSystemProvider} for the given URL.
098     *
099     * @param url The URL to query
100     * @return the {@link FileSystemProvider} for the given URI or null.
101     */
102    public FileSystemProvider getFileSystemProvider(final URL url) {
103        return getFileSystemProvider(Objects.requireNonNull(url, "url").getProtocol());
104    }
105
106}