    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 *   https://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019package org.apache.bcel.util;
    020
    021import java.io.Closeable;
    022import java.io.File;
    023import java.io.IOException;
    024import java.net.URI;
    025import java.net.URL;
    026import java.net.URLClassLoader;
    027import java.nio.file.DirectoryStream;
    028import java.nio.file.FileSystem;
    029import java.nio.file.FileSystems;
    030import java.nio.file.Files;
    031import java.nio.file.Path;
    032import java.nio.file.Paths;
    033import java.util.ArrayList;
    034import java.util.Collections;
    035import java.util.List;
    036import java.util.Map;
    037
    038import org.apache.commons.io.IOUtils;
    039
    040/**
    041 * Wraps a Java 9 JEP 220 modular runtime image. Requires the JRT NIO file system.
    042 *
    043 * @since 6.3
    044 */
    045public class ModularRuntimeImage implements Closeable {
    046
    047    static final String MODULES_PATH = File.separator + "modules";
    048    static final String PACKAGES_PATH = File.separator + "packages";
    049
    050    private final URLClassLoader classLoader;
    051    private final FileSystem fileSystem;
    052
    053    /**
    054     * Constructs a default instance.
    055     */
    056    @SuppressWarnings("resource") // See #close()
    057    public ModularRuntimeImage() {
    058        this(null, FileSystems.getFileSystem(URI.create("jrt:/")));
    059    }
    060
    061    /**
    062     * Constructs an instance using the JRT file system implementation from a specific Java Home.
    063     *
    064     * @param javaHome Path to a Java 9 or greater home.
    065     * @throws IOException an I/O error occurs accessing the file system
    066     */
    067    public ModularRuntimeImage(final String javaHome) throws IOException {
    068        final Map<String, ?> emptyMap = Collections.emptyMap();
    069        final Path jrePath = Paths.get(javaHome);
    070        final Path jrtFsPath = jrePath.resolve("lib").resolve("jrt-fs.jar");
    071        this.classLoader = URLClassLoader.newInstance(new URL[] {jrtFsPath.toUri().toURL()});
    072        this.fileSystem = FileSystems.newFileSystem(URI.create("jrt:/"), emptyMap, classLoader);
    073    }
    074
    075    private ModularRuntimeImage(final URLClassLoader cl, final FileSystem fs) {
    076        this.classLoader = cl;
    077        this.fileSystem = fs;
    078    }
    079
    080    @Override
    081    public void close() throws IOException {
    082        IOUtils.close(classLoader);
    083        if (fileSystem != null) {
    084            try {
    085                fileSystem.close();
    086            } catch (final UnsupportedOperationException e) {
    087                // do nothing
    088            }
    089        }
    090    }
    091
    092    public FileSystem getFileSystem() {
    093        return fileSystem;
    094    }
    095
    096    /**
    097     * Lists all entries in the given directory.
    098     *
    099     * @param dirPath directory path.
    100     * @return a list of dir entries if an I/O error occurs
    101     * @throws IOException an I/O error occurs accessing the file system
    102     */
    103    public List<Path> list(final Path dirPath) throws IOException {
    104        final List<Path> list = new ArrayList<>();
    105        try (DirectoryStream<Path> ds = Files.newDirectoryStream(dirPath)) {
    106            ds.forEach(list::add);
    107        }
    108        return list;
    109    }
    110
    111    /**
    112     * Lists all entries in the given directory.
    113     *
    114     * @param dirName directory path.
    115     * @return a list of dir entries if an I/O error occurs
    116     * @throws IOException an I/O error occurs accessing the file system
    117     */
    118    public List<Path> list(final String dirName) throws IOException {
    119        return list(fileSystem.getPath(dirName));
    120    }
    121
    122    /**
    123     * Lists all modules.
    124     *
    125     * @return a list of modules
    126     * @throws IOException an I/O error occurs accessing the file system
    127     */
    128    public List<Path> modules() throws IOException {
    129        return list(MODULES_PATH);
    130    }
    131
    132    /**
    133     * Lists all packages.
    134     *
    135     * @return a list of modules
    136     * @throws IOException an I/O error occurs accessing the file system
    137     */
    138    public List<Path> packages() throws IOException {
    139        return list(PACKAGES_PATH);
    140    }
    141
    142}