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