    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>SerializationUtils instances should NOT be constructed in standard programming.
    051     * Instead, the class should be used as {@code SerializationUtils.clone(object)}.</p>
    052     *
    053     * <p>This constructor is public to permit tools that require a JavaBean instance
    054     * to operate.</p>
    055     * @since 2.0
    056     */
    057    public SerializationUtils() {
    058        super();
    059    }
    060
    061    // Clone
    062    //-----------------------------------------------------------------------
    063    /**
    064     * <p>Deep clone an {@code Object} using serialization.</p>
    065     *
    066     * <p>This is many times slower than writing clone methods by hand
    067     * on all objects in your object graph. However, for complex object
    068     * graphs, or for those that don't support deep cloning this can
    069     * be a simple alternative implementation. Of course all the objects
    070     * must be {@code Serializable}.</p>
    071     *
    072     * @param <T> the type of the object involved
    073     * @param object  the {@code Serializable} object to clone
    074     * @return the cloned object
    075     * @throws SerializationException (runtime) if the serialization fails
    076     */
    077    public static <T extends Serializable> T clone(final T object) {
    078        if (object == null) {
    079            return null;
    080        }
    081        final byte[] objectData = serialize(object);
    082        final ByteArrayInputStream bais = new ByteArrayInputStream(objectData);
    083
    084        try (ClassLoaderAwareObjectInputStream in = new ClassLoaderAwareObjectInputStream(bais,
    085                object.getClass().getClassLoader())) {
    086            /*
    087             * when we serialize and deserialize an object,
    088             * it is reasonable to assume the deserialized object
    089             * is of the same type as the original serialized object
    090             */
    091            @SuppressWarnings("unchecked") // see above
    092            final T readObject = (T) in.readObject();
    093            return readObject;
    094
    095        } catch (final ClassNotFoundException ex) {
    096            throw new SerializationException("ClassNotFoundException while reading cloned object data", ex);
    097        } catch (final IOException ex) {
    098            throw new SerializationException("IOException while reading or closing cloned object data", ex);
    099        }
    100    }
    101
    102    /**
    103     * Performs a serialization roundtrip. Serializes and deserializes the given object, great for testing objects that
    104     * implement {@link Serializable}.
    105     *
    106     * @param <T>
    107     *           the type of the object involved
    108     * @param msg
    109     *            the object to roundtrip
    110     * @return the serialized and deserialized object
    111     * @since 3.3
    112     */
    113    @SuppressWarnings("unchecked") // OK, because we serialized a type `T`
    114    public static <T extends Serializable> T roundtrip(final T msg) {
    115        return (T) deserialize(serialize(msg));
    116    }
    117
    118    // Serialize
    119    //-----------------------------------------------------------------------
    120    /**
    121     * <p>Serializes an {@code Object} to the specified stream.</p>
    122     *
    123     * <p>The stream will be closed once the object is written.
    124     * This avoids the need for a finally clause, and maybe also exception
    125     * handling, in the application code.</p>
    126     *
    127     * <p>The stream passed in is not buffered internally within this method.
    128     * This is the responsibility of your application if desired.</p>
    129     *
    130     * @param obj  the object to serialize to bytes, may be null
    131     * @param outputStream  the stream to write to, must not be null
    132     * @throws NullPointerException if {@code outputStream} is {@code null}
    133     * @throws SerializationException (runtime) if the serialization fails
    134     */
    135    public static void serialize(final Serializable obj, final OutputStream outputStream) {
    136        Validate.notNull(outputStream, "The OutputStream must not be null");
    137        try (ObjectOutputStream out = new ObjectOutputStream(outputStream)) {
    138            out.writeObject(obj);
    139        } catch (final IOException ex) {
    140            throw new SerializationException(ex);
    141        }
    142    }
    143
    144    /**
    145     * <p>Serializes an {@code Object} to a byte array for
    146     * storage/serialization.</p>
    147     *
    148     * @param obj  the object to serialize to bytes
    149     * @return a byte[] with the converted Serializable
    150     * @throws SerializationException (runtime) if the serialization fails
    151     */
    152    public static byte[] serialize(final Serializable obj) {
    153        final ByteArrayOutputStream baos = new ByteArrayOutputStream(512);
    154        serialize(obj, baos);
    155        return baos.toByteArray();
    156    }
    157
    158    // Deserialize
    159    //-----------------------------------------------------------------------
    160    /**
    161     * <p>
    162     * Deserializes an {@code Object} from the specified stream.
    163     * </p>
    164     *
    165     * <p>
    166     * The stream will be closed once the object is written. This avoids the need for a finally clause, and maybe also
    167     * exception handling, in the application code.
    168     * </p>
    169     *
    170     * <p>
    171     * The stream passed in is not buffered internally within this method. This is the responsibility of your
    172     * application if desired.
    173     * </p>
    174     *
    175     * <p>
    176     * If the call site incorrectly types the return value, a {@link ClassCastException} is thrown from the call site.
    177     * Without Generics in this declaration, the call site must type cast and can cause the same ClassCastException.
    178     * Note that in both cases, the ClassCastException is in the call site, not in this method.
    179     * </p>
    180     *
    181     * @param <T>  the object type to be deserialized
    182     * @param inputStream
    183     *            the serialized object input stream, must not be null
    184     * @return the deserialized object
    185     * @throws NullPointerException if {@code inputStream} is {@code null}
    186     * @throws SerializationException (runtime) if the serialization fails
    187     */
    188    public static <T> T deserialize(final InputStream inputStream) {
    189        Validate.notNull(inputStream, "The InputStream must not be null");
    190        try (ObjectInputStream in = new ObjectInputStream(inputStream)) {
    191            @SuppressWarnings("unchecked")
    192            final T obj = (T) in.readObject();
    193            return obj;
    194        } catch (final ClassNotFoundException | IOException ex) {
    195            throw new SerializationException(ex);
    196        }
    197    }
    198
    199    /**
    200     * <p>
    201     * Deserializes a single {@code Object} from an array of bytes.
    202     * </p>
    203     *
    204     * <p>
    205     * If the call site incorrectly types the return value, a {@link ClassCastException} is thrown from the call site.
    206     * Without Generics in this declaration, the call site must type cast and can cause the same ClassCastException.
    207     * Note that in both cases, the ClassCastException is in the call site, not in this method.
    208     * </p>
    209     *
    210     * @param <T>  the object type to be deserialized
    211     * @param objectData
    212     *            the serialized object, must not be null
    213     * @return the deserialized object
    214     * @throws NullPointerException if {@code objectData} is {@code null}
    215     * @throws SerializationException (runtime) if the serialization fails
    216     */
    217    public static <T> T deserialize(final byte[] objectData) {
    218        Validate.notNull(objectData, "The byte[] must not be null");
    219        return deserialize(new ByteArrayInputStream(objectData));
    220    }
    221
    222    /**
    223     * <p>Custom specialization of the standard JDK {@link java.io.ObjectInputStream}
    224     * that uses a custom  {@code ClassLoader} to resolve a class.
    225     * If the specified {@code ClassLoader} is not able to resolve the class,
    226     * the context classloader of the current thread will be used.
    227     * This way, the standard deserialization work also in web-application
    228     * containers and application servers, no matter in which of the
    229     * {@code ClassLoader} the particular class that encapsulates
    230     * serialization/deserialization lives. </p>
    231     *
    232     * <p>For more in-depth information about the problem for which this
    233     * class here is a workaround, see the JIRA issue LANG-626. </p>
    234     */
    235     static class ClassLoaderAwareObjectInputStream extends ObjectInputStream {
    236        private static final Map<String, Class<?>> primitiveTypes =
    237                new HashMap<>();
    238
    239        static {
    240            primitiveTypes.put("byte", byte.class);
    241            primitiveTypes.put("short", short.class);
    242            primitiveTypes.put("int", int.class);
    243            primitiveTypes.put("long", long.class);
    244            primitiveTypes.put("float", float.class);
    245            primitiveTypes.put("double", double.class);
    246            primitiveTypes.put("boolean", boolean.class);
    247            primitiveTypes.put("char", char.class);
    248            primitiveTypes.put("void", void.class);
    249        }
    250
    251        private final ClassLoader classLoader;
    252
    253        /**
    254         * Constructor.
    255         * @param in The {@code InputStream}.
    256         * @param classLoader classloader to use
    257         * @throws IOException if an I/O error occurs while reading stream header.
    258         * @see java.io.ObjectInputStream
    259         */
    260        ClassLoaderAwareObjectInputStream(final InputStream in, final ClassLoader classLoader) throws IOException {
    261            super(in);
    262            this.classLoader = classLoader;
    263        }
    264
    265        /**
    266         * Overridden version that uses the parameterized {@code ClassLoader} or the {@code ClassLoader}
    267         * of the current {@code Thread} to resolve the class.
    268         * @param desc An instance of class {@code ObjectStreamClass}.
    269         * @return A {@code Class} object corresponding to {@code desc}.
    270         * @throws IOException Any of the usual Input/Output exceptions.
    271         * @throws ClassNotFoundException If class of a serialized object cannot be found.
    272         */
    273        @Override
    274        protected Class<?> resolveClass(final ObjectStreamClass desc) throws IOException, ClassNotFoundException {
    275            final String name = desc.getName();
    276            try {
    277                return Class.forName(name, false, classLoader);
    278            } catch (final ClassNotFoundException ex) {
    279                try {
    280                    return Class.forName(name, false, Thread.currentThread().getContextClassLoader());
    281                } catch (final ClassNotFoundException cnfe) {
    282                    final Class<?> cls = primitiveTypes.get(name);
    283                    if (cls != null) {
    284                        return cls;
    285                    }
    286                    throw cnfe;
    287                }
    288            }
    289        }
    290
    291    }
    292
    293}