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The AWS SDK for Java with support for OSGi. The AWS SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).

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/*
 * Copyright 2011-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * 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://aws.amazon.com/apache2.0
 *
 * This file 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 com.amazonaws.services.dynamodbv2.datamodeling;

import static com.amazonaws.util.Throwables.failure;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectWriter;

/**
 * A simple JSON marshaller that uses the Jackson JSON processor. It shares all limitations of that
 * library. For more information about Jackson, see: http://wiki.fasterxml.com/JacksonHome
 */
public class JsonMarshaller implements DynamoDBMarshaller {

    private static final ObjectMapper mapper = new ObjectMapper();
    private static final ObjectWriter writer = mapper.writer();

    /**
     * The value type.
     */
    private final Class valueType;

    /**
     * Constructs the JSON marshaller instance.
     * @param valueType The value type (for generic type erasure).
     */
    public JsonMarshaller(final Class valueType) {
        this.valueType = valueType;
    }

    /**
     * Constructs the JSON marshaller instance.
     */
    public JsonMarshaller() {
        this(null);
    }

    /**
     * Gets the value type.
     * @return The value type.
     */
    protected final Class getValueType() {
        return this.valueType;
    }

    @Override
    public String marshall(T obj) {

        try {
            return writer.writeValueAsString(obj);
        } catch (JsonProcessingException e) {
            throw failure(e,
                    "Unable to marshall the instance of " + obj.getClass()
                            + "into a string");
        }
    }

    @Override
    public T unmarshall(Class clazz, String json) {
        try {
            return mapper.readValue(json, (getValueType() == null ? clazz : getValueType()));
        } catch (Exception e) {
            throw failure(e, "Unable to unmarshall the string " + json
                    + "into " + clazz);
        }
    }
}