de.micromata.genome.db.jpa.xmldump.impl.HibernateCollectionConverter.java Source code

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Here is the source code for de.micromata.genome.db.jpa.xmldump.impl.HibernateCollectionConverter.java

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//
// Copyright (C) 2010-2016 Micromata GmbH
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

package de.micromata.genome.db.jpa.xmldump.impl;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.TreeMap;
import java.util.TreeSet;

import org.hibernate.collection.internal.PersistentSet;
import org.hibernate.collection.internal.PersistentSortedSet;
import org.hibernate.collection.spi.PersistentCollection;

import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.ConverterLookup;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;

/**
 * XStream converter that strips HB collections specific information and retrieves the underlying collection which is
 * then parsed by the delegated converter. This converter only takes care of the values inside the collections while the
 * mapper takes care of the collections naming.
 * 
 * @author Costin Leau
 * 
 */
public class HibernateCollectionConverter implements Converter {
    private Converter listSetConverter;

    private Converter mapConverter;

    private Converter treeMapConverter;

    private Converter treeSetConverter;

    private Converter defaultConverter;

    public HibernateCollectionConverter(ConverterLookup converterLookup) {
        listSetConverter = converterLookup.lookupConverterForType(ArrayList.class);
        mapConverter = converterLookup.lookupConverterForType(HashMap.class);
        treeMapConverter = converterLookup.lookupConverterForType(TreeMap.class);
        treeSetConverter = converterLookup.lookupConverterForType(TreeSet.class);
        defaultConverter = converterLookup.lookupConverterForType(Object.class);
    }

    /**
     * @see com.thoughtworks.xstream.converters.Converter#canConvert(java.lang.Class)
     */
    @Override
    public boolean canConvert(Class type) {
        return PersistentCollection.class.isAssignableFrom(type);
    }

    /**
     * @see com.thoughtworks.xstream.converters.Converter#marshal(java.lang.Object,
     *      com.thoughtworks.xstream.io.HierarchicalStreamWriter, com.thoughtworks.xstream.converters.MarshallingContext)
     */
    @Override
    public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {
        Object collection = source;

        if (source instanceof PersistentCollection) {
            PersistentCollection col = (PersistentCollection) source;
            col.forceInitialization();
            // ToDo ES: collection = col.getCollectionSnapshot().getSnapshot();
            collection = col.getStoredSnapshot();
        }

        // the set is returned as a map by Hibernate (unclear why exactly)
        if (source instanceof PersistentSortedSet) {
            collection = new TreeSet(((HashMap) collection).values());
        } else if (source instanceof PersistentSet) {
            // collection = new HashSet(((HashMap)collection).entrySet());
            collection = new HashSet(((HashMap) collection).values());
        }

        // delegate the collection to the approapriate converter
        if (listSetConverter.canConvert(collection.getClass())) {
            listSetConverter.marshal(collection, writer, context);
            return;
        }
        if (mapConverter.canConvert(collection.getClass())) {
            mapConverter.marshal(collection, writer, context);
            return;
        }
        if (treeMapConverter.canConvert(collection.getClass())) {
            treeMapConverter.marshal(collection, writer, context);
            return;
        }
        if (treeSetConverter.canConvert(collection.getClass())) {
            treeSetConverter.marshal(collection, writer, context);
            return;
        }

        defaultConverter.marshal(collection, writer, context);
    }

    /**
     * @see com.thoughtworks.xstream.converters.Converter#unmarshal(com.thoughtworks.xstream.io.HierarchicalStreamReader,
     *      com.thoughtworks.xstream.converters.UnmarshallingContext)
     */
    @Override
    public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
        return null;
    }
}