org.dswarm.graph.json.deserializer.StatementDeserializer.java Source code

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Here is the source code for org.dswarm.graph.json.deserializer.StatementDeserializer.java

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/**
 * Copyright (C) 2013  2015 SLUB Dresden & Avantgarde Labs GmbH (<code@dswarm.org>)
 *
 * 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.dswarm.graph.json.deserializer;

import java.io.IOException;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.ObjectCodec;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.JsonNodeType;

import org.dswarm.graph.json.LiteralNode;
import org.dswarm.graph.json.Node;
import org.dswarm.graph.json.Predicate;
import org.dswarm.graph.json.ResourceNode;
import org.dswarm.graph.json.Statement;

/**
 * @author tgaengler
 */
public class StatementDeserializer extends JsonDeserializer<Statement> {

    @Override
    public Statement deserialize(final JsonParser jp, final DeserializationContext ctxt) throws IOException {

        final ObjectCodec oc = jp.getCodec();

        if (oc == null) {

            return null;
        }

        final JsonNode node = oc.readTree(jp);

        if (node == null) {

            return null;
        }

        final JsonNode idNode = node.get("id");

        Long id = null;

        if (idNode != null) {

            try {

                id = idNode.asLong();
            } catch (final Exception e) {

                id = null;
            }
        }

        final JsonNode uuidNode = node.get("uuid");

        String uuid = null;

        if (uuidNode != null && JsonNodeType.NULL != uuidNode.getNodeType()) {

            uuid = uuidNode.asText();
        }

        final JsonNode subjectNode = node.get("s");

        if (subjectNode == null) {

            throw new JsonParseException("expected JSON node that represents the subject of a statement",
                    jp.getCurrentLocation());
        }

        final Node subject;

        if (subjectNode.get("uri") != null) {

            // resource node
            subject = subjectNode.traverse(oc).readValueAs(ResourceNode.class);
        } else {

            // bnode
            subject = subjectNode.traverse(oc).readValueAs(Node.class);
        }

        final JsonNode predicateNode = node.get("p");

        if (predicateNode == null) {

            throw new JsonParseException("expected JSON node that represents the predicate of a statement",
                    jp.getCurrentLocation());
        }

        final Predicate predicate = predicateNode.traverse(oc).readValueAs(Predicate.class);

        final JsonNode objectNode = node.get("o");

        if (objectNode == null) {

            throw new JsonParseException("expected JSON node that represents the object of a statement",
                    jp.getCurrentLocation());
        }

        final Node object;

        if (objectNode.get("uri") != null) {

            // resource node
            object = objectNode.traverse(oc).readValueAs(ResourceNode.class);
        } else if (objectNode.get("v") != null) {

            // literal node
            object = objectNode.traverse(oc).readValueAs(LiteralNode.class);
        } else {

            // bnode
            object = objectNode.traverse(oc).readValueAs(Node.class);
        }

        final JsonNode orderNode = node.get("order");

        Long order = null;

        if (orderNode != null) {

            try {

                order = orderNode.asLong();
            } catch (final Exception e) {

                order = null;
            }
        }

        final JsonNode evidenceNode = node.get("evidence");

        String evidence = null;

        if (evidenceNode != null) {

            evidence = evidenceNode.asText();
        }

        final JsonNode confidenceNode = node.get("confidence");

        String confidence = null;

        if (confidenceNode != null) {

            confidence = confidenceNode.asText();
        }

        final Statement statement = new Statement(subject, predicate, object);

        if (id != null) {

            statement.setId(id);
        }

        if (uuid != null) {

            statement.setUUID(uuid);
        }

        if (order != null) {

            statement.setOrder(order);
        }

        if (evidence != null) {

            statement.setEvidence(evidence);
        }

        if (confidence != null) {

            statement.setConfidence(confidence);
        }

        return statement;
    }
}