ObjectReader.java

/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.exoplatform.commons.serialization.serial;

import java.io.IOException;
import java.io.InputStream;
import java.io.InvalidClassException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.io.StreamCorruptedException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.exoplatform.commons.serialization.SerializationContext;
import org.exoplatform.commons.serialization.api.TypeConverter;
import org.exoplatform.commons.serialization.api.factory.ObjectFactory;
import org.exoplatform.commons.serialization.model.ClassTypeModel;
import org.exoplatform.commons.serialization.model.ConvertedTypeModel;
import org.exoplatform.commons.serialization.model.FieldModel;

/**
 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
 * @version $Revision$
 */
public class ObjectReader extends ObjectInputStream {

    /** . */
    private final SerializationContext context;

    /** . */
    private final Map<Integer, Object> idToObject;

    /** . */
    private final Map<Integer, List<FutureFieldUpdate<?>>> idToResolutions;

    public ObjectReader(SerializationContext context, InputStream in) throws IOException {
        super(in);

        //
        enableResolveObject(true);

        //
        this.context = context;
        this.idToObject = new HashMap<Integer, Object>();
        this.idToResolutions = new HashMap<Integer, List<FutureFieldUpdate<?>>>();
    }

    private <O> O instantiate(ClassTypeModel<O> typeModel, Map<FieldModel<? super O, ?>, ?> state) throws InvalidClassException {
        try {
            ObjectFactory<? super O> factory = context.getFactory(typeModel.getJavaType());

            //
            return factory.create(typeModel.getJavaType(), state);
        } catch (Exception e) {
            InvalidClassException ice = new InvalidClassException("Cannot instantiate object from class "
                    + typeModel.getJavaType().getName());
            ice.initCause(e);
            throw ice;
        }
    }

    protected <O> O instantiate(int id, DataContainer container, ClassTypeModel<O> typeModel) throws IOException {
        Map<FieldModel<? super O, ?>, Object> state = new HashMap<FieldModel<? super O, ?>, Object>();
        ClassTypeModel<? super O> currentTypeModel = typeModel;
        List<FieldUpdate<O>> sets = new ArrayList<FieldUpdate<O>>();
        while (currentTypeModel != null) {
            if (currentTypeModel instanceof ClassTypeModel) {
                for (FieldModel<? super O, ?> fieldModel : currentTypeModel.getFields()) {
                    if (!fieldModel.isTransient()) {
                        switch (container.readInt()) {
                            case DataKind.NULL_VALUE:
                                state.put(fieldModel, null);
                                break;
                            case DataKind.OBJECT_REF:
                                int refId = container.readInt();
                                Object refO = idToObject.get(refId);
                                if (refO != null) {
                                    state.put(fieldModel, refO);
                                } else {
                                    sets.add(new FieldUpdate<O>(refId, fieldModel));
                                }
                                break;
                            case DataKind.OBJECT:
                                Object o = container.readObject();
                                state.put(fieldModel, o);
                                break;
                        }
                    }
                }
            }
            currentTypeModel = currentTypeModel.getSuperType();
        }

        //
        O instance = instantiate(typeModel, state);

        // Create future field updates
        for (FieldUpdate<O> set : sets) {
            List<FutureFieldUpdate<?>> resolutions = idToResolutions.get(set.ref);
            if (resolutions == null) {
                resolutions = new ArrayList<FutureFieldUpdate<?>>();
                idToResolutions.put(set.ref, resolutions);
            }
            resolutions.add(new FutureFieldUpdate<O>(instance, set.fieldModel));
        }

        //
        idToObject.put(id, instance);

        // Resolve future field updates
        List<FutureFieldUpdate<?>> resolutions = idToResolutions.remove(id);
        if (resolutions != null) {
            for (FutureFieldUpdate<?> resolution : resolutions) {
                resolution.fieldModel.castAndSet(resolution.target, instance);
            }
        }

        //
        return instance;
    }

    private static class FieldUpdate<O> {
        /** . */
        private final int ref;

        /** . */
        private final FieldModel<? super O, ?> fieldModel;

        private FieldUpdate(int ref, FieldModel<? super O, ?> fieldModel) {
            this.ref = ref;
            this.fieldModel = fieldModel;
        }
    }

    private static class FutureFieldUpdate<O> {
        /** . */
        private final O target;

        /** . */
        private final FieldModel<? super O, ?> fieldModel;

        private FutureFieldUpdate(O target, FieldModel<? super O, ?> fieldModel) {
            this.target = target;
            this.fieldModel = fieldModel;
        }
    }

    private Object read(DataContainer container) throws IOException {
        int sw = container.readInt();
        switch (sw) {
            case DataKind.OBJECT_REF: {
                int id = container.readInt();
                Object o1 = idToObject.get(id);
                if (o1 == null) {
                    throw new AssertionError();
                }
                return o1;
            }
            case DataKind.OBJECT: {
                int id = container.readInt();
                Class<?> clazz = (Class) container.readObject();
                ClassTypeModel<?> typeModel = (ClassTypeModel<?>) context.getTypeDomain().getTypeModel(clazz);
                return instantiate(id, container, typeModel);
            }
            case DataKind.CONVERTED_OBJECT: {
                Class<?> tclazz = (Class<?>) container.readObject();
                ConvertedTypeModel<?, ?> ctm = (ConvertedTypeModel<?, ?>) context.getTypeDomain().getTypeModel(tclazz);
                return convertObject(container, ctm);
            }
            case DataKind.SERIALIZED_OBJECT:
                return container.readObject();
            default:
                throw new StreamCorruptedException("Unrecognized data " + sw);
        }
    }

    private <O, T> O convertObject(DataContainer container, ConvertedTypeModel<O, T> convertedType) throws IOException {
        Object inner = resolveObject(container);
        T t = convertedType.getTargetType().getJavaType().cast(inner);

        TypeConverter<O, T> converter;
        try {
            converter = convertedType.getConverterJavaType().newInstance();
        } catch (Exception e) {
            throw new AssertionError(e);
        }

        //
        O o = null;
        try {
            o = converter.read(t);
        } catch (Exception e) {
            InvalidObjectException ioe = new InvalidObjectException("The object " + t + " conversion throw an exception "
                    + converter);
            ioe.initCause(e);
            throw ioe;
        }
        if (o == null) {
            throw new InvalidObjectException("The object " + t + " was converted to null by converter " + converter);
        }

        //
        return o;
    }

    @Override
    protected Object resolveObject(Object obj) throws IOException {
        if (obj instanceof DataContainer) {
            return read((DataContainer) obj);
        } else {
            return obj;
        }
    }

    @Override
    protected Class<?> resolveClass(ObjectStreamClass desc) throws IOException, ClassNotFoundException {
        try {
            ClassLoader cl = Thread.currentThread().getContextClassLoader();
            String name = desc.getName();
            return Class.forName(name, false, cl);
        } catch (ClassNotFoundException ex) {
            return super.resolveClass(desc);
        }
    }
}