    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.IOException;
    021import java.io.InputStream;
    022import java.lang.ref.SoftReference;
    023import java.util.HashMap;
    024import java.util.Map;
    025
    026import org.apache.bcel.classfile.ClassParser;
    027import org.apache.bcel.classfile.JavaClass;
    028
    029/**
    030 * This repository is used in situations where a Class is created outside the realm of a ClassLoader. Classes are loaded from the file systems using the paths
    031 * specified in the given class path. By default, this is the value returned by ClassPath.getClassPath(). This repository holds onto classes with
    032 * SoftReferences, and will reload as needed, in cases where memory sizes are important.<br>
    033 *
    034 * @see org.apache.bcel.Repository
    035 */
    036public class MemorySensitiveClassPathRepository implements Repository {
    037
    038    private ClassPath _path = null;
    039    private final Map<String, SoftReference<JavaClass>> _loadedClasses = new HashMap<>(); // CLASSNAME X JAVACLASS
    040
    041    public MemorySensitiveClassPathRepository(final ClassPath path) {
    042        this._path = path;
    043    }
    044
    045    /**
    046     * Store a new JavaClass instance into this Repository.
    047     */
    048    @Override
    049    public void storeClass(final JavaClass clazz) {
    050        _loadedClasses.put(clazz.getClassName(), new SoftReference<>(clazz));
    051        clazz.setRepository(this);
    052    }
    053
    054    /**
    055     * Remove class from repository
    056     */
    057    @Override
    058    public void removeClass(final JavaClass clazz) {
    059        _loadedClasses.remove(clazz.getClassName());
    060    }
    061
    062    /**
    063     * Find an already defined (cached) JavaClass object by name.
    064     */
    065    @Override
    066    public JavaClass findClass(final String className) {
    067        final SoftReference<JavaClass> ref = _loadedClasses.get(className);
    068        if (ref == null) {
    069            return null;
    070        }
    071        return ref.get();
    072    }
    073
    074    /**
    075     * Find a JavaClass object by name. If it is already in this Repository, the Repository version is returned. Otherwise, the Repository's classpath is
    076     * searched for the class (and it is added to the Repository if found).
    077     *
    078     * @param className
    079     *            the name of the class
    080     * @return the JavaClass object
    081     * @throws ClassNotFoundException
    082     *             if the class is not in the Repository, and could not be found on the classpath
    083     */
    084    @Override
    085    public JavaClass loadClass(String className) throws ClassNotFoundException {
    086        if ((className == null) || className.isEmpty()) {
    087            throw new IllegalArgumentException("Invalid class name " + className);
    088        }
    089        className = className.replace('/', '.'); // Just in case, canonical form
    090        final JavaClass clazz = findClass(className);
    091        if (clazz != null) {
    092            return clazz;
    093        }
    094        try {
    095            return loadClass(_path.getInputStream(className), className);
    096        } catch (final IOException e) {
    097            throw new ClassNotFoundException("Exception while looking for class " + className + ": " + e, e);
    098        }
    099    }
    100
    101    /**
    102     * Find the JavaClass object for a runtime Class object. If a class with the same name is already in this Repository, the Repository version is returned.
    103     * Otherwise, getResourceAsStream() is called on the Class object to find the class's representation. If the representation is found, it is added to the
    104     * Repository.
    105     *
    106     * @see Class
    107     * @param clazz
    108     *            the runtime Class object
    109     * @return JavaClass object for given runtime class
    110     * @throws ClassNotFoundException
    111     *             if the class is not in the Repository, and its representation could not be found
    112     */
    113    @Override
    114    public JavaClass loadClass(final Class<?> clazz) throws ClassNotFoundException {
    115        final String className = clazz.getName();
    116        final JavaClass repositoryClass = findClass(className);
    117        if (repositoryClass != null) {
    118            return repositoryClass;
    119        }
    120        String name = className;
    121        final int i = name.lastIndexOf('.');
    122        if (i > 0) {
    123            name = name.substring(i + 1);
    124        }
    125        JavaClass cls = null;
    126        try (InputStream clsStream = clazz.getResourceAsStream(name + ".class")) {
    127            return cls = loadClass(clsStream, className);
    128        } catch (final IOException e) {
    129            return cls;
    130        }
    131
    132    }
    133
    134    private JavaClass loadClass(final InputStream is, final String className) throws ClassNotFoundException {
    135        try {
    136            if (is != null) {
    137                final ClassParser parser = new ClassParser(is, className);
    138                final JavaClass clazz = parser.parse();
    139                storeClass(clazz);
    140                return clazz;
    141            }
    142        } catch (final IOException e) {
    143            throw new ClassNotFoundException("Exception while looking for class " + className + ": " + e, e);
    144        } finally {
    145            if (is != null) {
    146                try {
    147                    is.close();
    148                } catch (final IOException e) {
    149                    // ignored
    150                }
    151            }
    152        }
    153        throw new ClassNotFoundException("SyntheticRepository could not load " + className);
    154    }
    155
    156    /**
    157     * ClassPath associated with the Repository.
    158     */
    159    @Override
    160    public ClassPath getClassPath() {
    161        return _path;
    162    }
    163
    164    /**
    165     * Clear all entries from cache.
    166     */
    167    @Override
    168    public void clear() {
    169        _loadedClasses.clear();
    170    }
    171}