    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 */
    017package org.apache.bcel.util;
    018
    019import java.io.Closeable;
    020import java.io.File;
    021import java.io.IOException;
    022import java.net.URI;
    023import java.net.URL;
    024import java.net.URLClassLoader;
    025import java.nio.file.DirectoryStream;
    026import java.nio.file.FileSystem;
    027import java.nio.file.FileSystems;
    028import java.nio.file.Files;
    029import java.nio.file.Path;
    030import java.nio.file.Paths;
    031import java.util.ArrayList;
    032import java.util.Collections;
    033import java.util.List;
    034import java.util.Map;
    035
    036/**
    037 * Wraps a Java 9 JEP 220 modular runtime image. Requires the JRT NIO file system.
    038 *
    039 * @since 6.3
    040 */
    041public class ModularRuntimeImage implements Closeable {
    042
    043    static final String MODULES_PATH = File.separator + "modules";
    044    static final String PACKAGES_PATH = File.separator + "packages";
    045
    046    private final URLClassLoader classLoader;
    047    private final FileSystem fileSystem;
    048
    049    /**
    050     * Constructs a default instance.
    051     */
    052    @SuppressWarnings("resource") // See #close()
    053    public ModularRuntimeImage() {
    054        this(null, FileSystems.getFileSystem(URI.create("jrt:/")));
    055    }
    056
    057    /**
    058     * Constructs an instance using the JRT file system implementation from a specific Java Home.
    059     *
    060     * @param javaHome Path to a Java 9 or greater home.
    061     *
    062     * @throws IOException an I/O error occurs accessing the file system
    063     */
    064    public ModularRuntimeImage(final String javaHome) throws IOException {
    065        final Map<String, ?> emptyMap = Collections.emptyMap();
    066        final Path jrePath = Paths.get(javaHome);
    067        final Path jrtFsPath = jrePath.resolve("lib").resolve("jrt-fs.jar");
    068        this.classLoader = URLClassLoader.newInstance(new URL[] {jrtFsPath.toUri().toURL()});
    069        this.fileSystem = FileSystems.newFileSystem(URI.create("jrt:/"), emptyMap, classLoader);
    070    }
    071
    072    private ModularRuntimeImage(final URLClassLoader cl, final FileSystem fs) {
    073        this.classLoader = cl;
    074        this.fileSystem = fs;
    075    }
    076
    077    @Override
    078    public void close() throws IOException {
    079        if (classLoader != null) {
    080            classLoader.close();
    081        }
    082        if (fileSystem != null) {
    083            fileSystem.close();
    084        }
    085    }
    086
    087    public FileSystem getFileSystem() {
    088        return fileSystem;
    089    }
    090
    091    /**
    092     * Lists all entries in the given directory.
    093     *
    094     * @param dirPath directory path.
    095     * @return a list of dir entries if an I/O error occurs
    096     * @throws IOException an I/O error occurs accessing the file system
    097     */
    098    public List<Path> list(final Path dirPath) throws IOException {
    099        final List<Path> list = new ArrayList<>();
    100        try (DirectoryStream<Path> ds = Files.newDirectoryStream(dirPath)) {
    101            ds.forEach(list::add);
    102        }
    103        return list;
    104    }
    105
    106    /**
    107     * Lists all entries in the given directory.
    108     *
    109     * @param dirName directory path.
    110     * @return a list of dir entries if an I/O error occurs
    111     * @throws IOException an I/O error occurs accessing the file system
    112     */
    113    public List<Path> list(final String dirName) throws IOException {
    114        return list(fileSystem.getPath(dirName));
    115    }
    116
    117    /**
    118     * Lists all modules.
    119     *
    120     * @return a list of modules
    121     * @throws IOException an I/O error occurs accessing the file system
    122     */
    123    public List<Path> modules() throws IOException {
    124        return list(MODULES_PATH);
    125    }
    126
    127    /**
    128     * Lists all packages.
    129     *
    130     * @return a list of modules
    131     * @throws IOException an I/O error occurs accessing the file system
    132     */
    133    public List<Path> packages() throws IOException {
    134        return list(PACKAGES_PATH);
    135    }
    136
    137}