    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.bcel.util;
    019
    020import java.io.Closeable;
    021import java.io.File;
    022import java.io.IOException;
    023import java.net.URI;
    024import java.net.URL;
    025import java.net.URLClassLoader;
    026import java.nio.file.DirectoryStream;
    027import java.nio.file.FileSystem;
    028import java.nio.file.FileSystems;
    029import java.nio.file.Files;
    030import java.nio.file.Path;
    031import java.nio.file.Paths;
    032import java.util.ArrayList;
    033import java.util.Collections;
    034import java.util.Iterator;
    035import java.util.List;
    036import java.util.Map;
    037
    038/**
    039 * Wraps a Java 9 JEP 220 modular runtime image. Requires the JRT NIO file system.
    040 *
    041 * @since 6.3
    042 */
    043public class ModularRuntimeImage implements Closeable {
    044
    045    static final String MODULES_PATH = File.separator + "modules";
    046    static final String PACKAGES_PATH = File.separator + "packages";
    047
    048    private final URLClassLoader classLoader;
    049    private final FileSystem fileSystem;
    050
    051    /**
    052     * Constructs a default instance.
    053     *
    054     * @throws IOException
    055     *             an I/O error occurs accessing the file system
    056     */
    057    public ModularRuntimeImage() throws IOException {
    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
    065     *            Path to a Java 9 or greater home.
    066     *
    067     * @throws IOException
    068     *             an I/O error occurs accessing the file system
    069     */
    070    public ModularRuntimeImage(final String javaHome) throws IOException {
    071        final Map<String, ?> emptyMap = Collections.emptyMap();
    072        final Path jrePath = Paths.get(javaHome);
    073        final Path jrtFsPath = jrePath.resolve("lib").resolve("jrt-fs.jar");
    074        this.classLoader = new URLClassLoader(new URL[] {jrtFsPath.toUri().toURL() });
    075        this.fileSystem = FileSystems.newFileSystem(URI.create("jrt:/"), emptyMap, classLoader);
    076    }
    077
    078    private ModularRuntimeImage(final URLClassLoader cl, final FileSystem fs) {
    079        this.classLoader = cl;
    080        this.fileSystem = fs;
    081    }
    082
    083    @Override
    084    public void close() throws IOException {
    085        if (classLoader != null) {
    086            if (classLoader != null) {
    087                classLoader.close();
    088            }
    089            if (fileSystem != null) {
    090                fileSystem.close();
    091            }
    092        }
    093    }
    094
    095    /**
    096     * Lists all entries in the given directory.
    097     *
    098     * @param dirPath
    099     *            directory path.
    100     * @return a list of dir entries if an I/O error occurs
    101     * @throws IOException
    102     *             an I/O error occurs accessing the file system
    103     */
    104    public List<Path> list(final Path dirPath) throws IOException {
    105        final List<Path> list = new ArrayList<>();
    106        try (DirectoryStream<Path> ds = Files.newDirectoryStream(dirPath)) {
    107            final Iterator<Path> iterator = ds.iterator();
    108            while (iterator.hasNext()) {
    109                list.add(iterator.next());
    110            }
    111        }
    112        return list;
    113    }
    114
    115    /**
    116     * Lists all entries in the given directory.
    117     *
    118     * @param dirName
    119     *            directory path.
    120     * @return a list of dir entries if an I/O error occurs
    121     * @throws IOException
    122     *             an I/O error occurs accessing the file system
    123     */
    124    public List<Path> list(final String dirName) throws IOException {
    125        return list(fileSystem.getPath(dirName));
    126    }
    127
    128    /**
    129     * Lists all modules.
    130     *
    131     * @return a list of modules
    132     * @throws IOException
    133     *             an I/O error occurs accessing the file system
    134     */
    135    public List<Path> modules() throws IOException {
    136        return list(MODULES_PATH);
    137    }
    138
    139    /**
    140     * Lists all packages.
    141     *
    142     * @return a list of modules
    143     * @throws IOException
    144     *             an I/O error occurs accessing the file system
    145     */
    146    public List<Path> packages() throws IOException {
    147        return list(PACKAGES_PATH);
    148    }
    149
    150    public FileSystem getFileSystem() {
    151        return fileSystem;
    152    }
    153
    154}