    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.commons.lang3;
    018
    019import java.io.ByteArrayInputStream;
    020import java.io.ByteArrayOutputStream;
    021import java.io.IOException;
    022import java.io.InputStream;
    023import java.io.ObjectInputStream;
    024import java.io.ObjectOutputStream;
    025import java.io.ObjectStreamClass;
    026import java.io.OutputStream;
    027import java.io.Serializable;
    028import java.util.HashMap;
    029import java.util.Map;
    030
    031/**
    032 * <p>Assists with the serialization process and performs additional functionality based
    033 * on serialization.</p>
    034 *
    035 * <ul>
    036 * <li>Deep clone using serialization
    037 * <li>Serialize managing finally and IOException
    038 * <li>Deserialize managing finally and IOException
    039 * </ul>
    040 *
    041 * <p>This class throws exceptions for invalid {@code null} inputs.
    042 * Each method documents its behavior in more detail.</p>
    043 *
    044 * <p>#ThreadSafe#</p>
    045 * @since 1.0
    046 */
    047public class SerializationUtils {
    048
    049    /**
    050     * <p>Custom specialization of the standard JDK {@link java.io.ObjectInputStream}
    051     * that uses a custom  {@code ClassLoader} to resolve a class.
    052     * If the specified {@code ClassLoader} is not able to resolve the class,
    053     * the context classloader of the current thread will be used.
    054     * This way, the standard deserialization work also in web-application
    055     * containers and application servers, no matter in which of the
    056     * {@code ClassLoader} the particular class that encapsulates
    057     * serialization/deserialization lives. </p>
    058     *
    059     * <p>For more in-depth information about the problem for which this
    060     * class here is a workaround, see the JIRA issue LANG-626. </p>
    061     */
    062     static class ClassLoaderAwareObjectInputStream extends ObjectInputStream {
    063        private static final Map<String, Class<?>> primitiveTypes =
    064                new HashMap<>();
    065
    066        static {
    067            primitiveTypes.put("byte", byte.class);
    068            primitiveTypes.put("short", short.class);
    069            primitiveTypes.put("int", int.class);
    070            primitiveTypes.put("long", long.class);
    071            primitiveTypes.put("float", float.class);
    072            primitiveTypes.put("double", double.class);
    073            primitiveTypes.put("boolean", boolean.class);
    074            primitiveTypes.put("char", char.class);
    075            primitiveTypes.put("void", void.class);
    076        }
    077
    078        private final ClassLoader classLoader;
    079
    080        /**
    081         * Constructor.
    082         * @param in The {@code InputStream}.
    083         * @param classLoader classloader to use
    084         * @throws IOException if an I/O error occurs while reading stream header.
    085         * @see java.io.ObjectInputStream
    086         */
    087        ClassLoaderAwareObjectInputStream(final InputStream in, final ClassLoader classLoader) throws IOException {
    088            super(in);
    089            this.classLoader = classLoader;
    090        }
    091
    092        /**
    093         * Overridden version that uses the parameterized {@code ClassLoader} or the {@code ClassLoader}
    094         * of the current {@code Thread} to resolve the class.
    095         * @param desc An instance of class {@code ObjectStreamClass}.
    096         * @return A {@code Class} object corresponding to {@code desc}.
    097         * @throws IOException Any of the usual Input/Output exceptions.
    098         * @throws ClassNotFoundException If class of a serialized object cannot be found.
    099         */
    100        @Override
    101        protected Class<?> resolveClass(final ObjectStreamClass desc) throws IOException, ClassNotFoundException {
    102            final String name = desc.getName();
    103            try {
    104                return Class.forName(name, false, classLoader);
    105            } catch (final ClassNotFoundException ex) {
    106                try {
    107                    return Class.forName(name, false, Thread.currentThread().getContextClassLoader());
    108                } catch (final ClassNotFoundException cnfe) {
    109                    final Class<?> cls = primitiveTypes.get(name);
    110                    if (cls != null) {
    111                        return cls;
    112                    }
    113                    throw cnfe;
    114                }
    115            }
    116        }
    117
    118    }
    119
    120    /**
    121     * <p>Deep clone an {@code Object} using serialization.</p>
    122     *
    123     * <p>This is many times slower than writing clone methods by hand
    124     * on all objects in your object graph. However, for complex object
    125     * graphs, or for those that don't support deep cloning this can
    126     * be a simple alternative implementation. Of course all the objects
    127     * must be {@code Serializable}.</p>
    128     *
    129     * @param <T> the type of the object involved
    130     * @param object  the {@code Serializable} object to clone
    131     * @return the cloned object
    132     * @throws SerializationException (runtime) if the serialization fails
    133     */
    134    public static <T extends Serializable> T clone(final T object) {
    135        if (object == null) {
    136            return null;
    137        }
    138        final byte[] objectData = serialize(object);
    139        final ByteArrayInputStream bais = new ByteArrayInputStream(objectData);
    140
    141        try (ClassLoaderAwareObjectInputStream in = new ClassLoaderAwareObjectInputStream(bais,
    142                object.getClass().getClassLoader())) {
    143            /*
    144             * when we serialize and deserialize an object,
    145             * it is reasonable to assume the deserialized object
    146             * is of the same type as the original serialized object
    147             */
    148            @SuppressWarnings("unchecked") // see above
    149            final T readObject = (T) in.readObject();
    150            return readObject;
    151
    152        } catch (final ClassNotFoundException ex) {
    153            throw new SerializationException("ClassNotFoundException while reading cloned object data", ex);
    154        } catch (final IOException ex) {
    155            throw new SerializationException("IOException while reading or closing cloned object data", ex);
    156        }
    157    }
    158
    159    /**
    160     * <p>
    161     * Deserializes a single {@code Object} from an array of bytes.
    162     * </p>
    163     *
    164     * <p>
    165     * If the call site incorrectly types the return value, a {@link ClassCastException} is thrown from the call site.
    166     * Without Generics in this declaration, the call site must type cast and can cause the same ClassCastException.
    167     * Note that in both cases, the ClassCastException is in the call site, not in this method.
    168     * </p>
    169     *
    170     * @param <T>  the object type to be deserialized
    171     * @param objectData
    172     *            the serialized object, must not be null
    173     * @return the deserialized object
    174     * @throws NullPointerException if {@code objectData} is {@code null}
    175     * @throws SerializationException (runtime) if the serialization fails
    176     */
    177    public static <T> T deserialize(final byte[] objectData) {
    178        Validate.notNull(objectData, "objectData");
    179        return deserialize(new ByteArrayInputStream(objectData));
    180    }
    181
    182    /**
    183     * <p>
    184     * Deserializes an {@code Object} from the specified stream.
    185     * </p>
    186     *
    187     * <p>
    188     * The stream will be closed once the object is written. This avoids the need for a finally clause, and maybe also
    189     * exception handling, in the application code.
    190     * </p>
    191     *
    192     * <p>
    193     * The stream passed in is not buffered internally within this method. This is the responsibility of your
    194     * application if desired.
    195     * </p>
    196     *
    197     * <p>
    198     * If the call site incorrectly types the return value, a {@link ClassCastException} is thrown from the call site.
    199     * Without Generics in this declaration, the call site must type cast and can cause the same ClassCastException.
    200     * Note that in both cases, the ClassCastException is in the call site, not in this method.
    201     * </p>
    202     *
    203     * @param <T>  the object type to be deserialized
    204     * @param inputStream
    205     *            the serialized object input stream, must not be null
    206     * @return the deserialized object
    207     * @throws NullPointerException if {@code inputStream} is {@code null}
    208     * @throws SerializationException (runtime) if the serialization fails
    209     */
    210    @SuppressWarnings("resource") // inputStream is managed by the caller
    211    public static <T> T deserialize(final InputStream inputStream) {
    212        Validate.notNull(inputStream, "inputStream");
    213        try (ObjectInputStream in = new ObjectInputStream(inputStream)) {
    214            @SuppressWarnings("unchecked")
    215            final T obj = (T) in.readObject();
    216            return obj;
    217        } catch (final ClassNotFoundException | IOException ex) {
    218            throw new SerializationException(ex);
    219        }
    220    }
    221
    222    /**
    223     * Performs a serialization roundtrip. Serializes and deserializes the given object, great for testing objects that
    224     * implement {@link Serializable}.
    225     *
    226     * @param <T>
    227     *           the type of the object involved
    228     * @param obj
    229     *            the object to roundtrip
    230     * @return the serialized and deserialized object
    231     * @since 3.3
    232     */
    233    @SuppressWarnings("unchecked") // OK, because we serialized a type `T`
    234    public static <T extends Serializable> T roundtrip(final T obj) {
    235        return (T) deserialize(serialize(obj));
    236    }
    237
    238    /**
    239     * <p>Serializes an {@code Object} to a byte array for
    240     * storage/serialization.</p>
    241     *
    242     * @param obj  the object to serialize to bytes
    243     * @return a byte[] with the converted Serializable
    244     * @throws SerializationException (runtime) if the serialization fails
    245     */
    246    public static byte[] serialize(final Serializable obj) {
    247        final ByteArrayOutputStream baos = new ByteArrayOutputStream(512);
    248        serialize(obj, baos);
    249        return baos.toByteArray();
    250    }
    251
    252    /**
    253     * <p>Serializes an {@code Object} to the specified stream.</p>
    254     *
    255     * <p>The stream will be closed once the object is written.
    256     * This avoids the need for a finally clause, and maybe also exception
    257     * handling, in the application code.</p>
    258     *
    259     * <p>The stream passed in is not buffered internally within this method.
    260     * This is the responsibility of your application if desired.</p>
    261     *
    262     * @param obj  the object to serialize to bytes, may be null
    263     * @param outputStream  the stream to write to, must not be null
    264     * @throws NullPointerException if {@code outputStream} is {@code null}
    265     * @throws SerializationException (runtime) if the serialization fails
    266     */
    267    @SuppressWarnings("resource") // outputStream is managed by the caller
    268    public static void serialize(final Serializable obj, final OutputStream outputStream) {
    269        Validate.notNull(outputStream, "outputStream");
    270        try (ObjectOutputStream out = new ObjectOutputStream(outputStream)) {
    271            out.writeObject(obj);
    272        } catch (final IOException ex) {
    273            throw new SerializationException(ex);
    274        }
    275    }
    276
    277    /**
    278     * <p>SerializationUtils instances should NOT be constructed in standard programming.
    279     * Instead, the class should be used as {@code SerializationUtils.clone(object)}.</p>
    280     *
    281     * <p>This constructor is public to permit tools that require a JavaBean instance
    282     * to operate.</p>
    283     * @since 2.0
    284     */
    285    public SerializationUtils() {
    286    }
    287
    288}