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Maps MongoDB objects to POJOs using Jackson

There is a newer version: 5.0.2

/*
 * Copyright 2011 VZ Netzwerke Ltd
 * Copyright 2014 devbliss 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 org.mongojack.internal.stream;

import java.io.IOException;

import org.bson.BSONObject;
import org.bson.io.OutputBuffer;
import org.mongojack.MongoJsonMappingException;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.mongodb.DBEncoder;
import com.mongodb.MongoException;

import de.undercouch.bson4jackson.BsonGenerator;

/**
 * DBEncoder that uses bson4jackson if the object is a JacksonDBObject
 */
public class JacksonDBEncoder implements DBEncoder {
    private final ObjectMapper objectMapper;
    private final DBEncoder defaultDBEncoder;

    public JacksonDBEncoder(ObjectMapper objectMapper,
            DBEncoder defaultDBEncoder) {
        this.objectMapper = objectMapper;
        this.defaultDBEncoder = defaultDBEncoder;
    }

    @Override
    public int writeObject(OutputBuffer buf, BSONObject object) {
        if (object instanceof JacksonDBObject) {
            JacksonDBObject jacksonDbObject = (JacksonDBObject) object;
            OutputBufferOutputStream stream = new OutputBufferOutputStream(buf);
            BsonGenerator generator = new DBEncoderBsonGenerator(
                    JsonGenerator.Feature.collectDefaults(), stream);
            try {
                objectMapper.writerWithView(jacksonDbObject.getView())
                        .writeValue(generator, jacksonDbObject.getObject());
                // The generator buffers everything so that it can write the
                // number of bytes to the stream
                generator.close();
            } catch (JsonMappingException e) {
                throw new MongoJsonMappingException(e);
            } catch (IOException e) {
                throw new MongoException("Error writing object out", e);
            }
            return stream.getCount();
        } else {
            return defaultDBEncoder.writeObject(buf, object);
        }
    }
}