org.agorava.twitter.jackson.LocalTrendsDeserializer.java Source code

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Here is the source code for org.agorava.twitter.jackson.LocalTrendsDeserializer.java

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/*
 * Copyright 2013 Agorava
 *
 * 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.agorava.twitter.jackson;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonNode;
import org.agorava.twitter.model.Trend;
import org.agorava.twitter.model.Trends;

import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.Iterator;
import java.util.List;

/**
 * Deserializer to read local trends data into a LocalTrendsHolder object.
 *
 * @author Craig Walls
 * @author Antoine Sabot-Durand
 */
class LocalTrendsDeserializer extends JsonDeserializer<LocalTrendsHolder> {

    @Override
    public LocalTrendsHolder deserialize(JsonParser jp, DeserializationContext ctxt)
            throws IOException, JsonProcessingException {
        JsonNode tree = jp.readValueAsTree();
        Iterator<JsonNode> dayIt = tree.iterator();
        if (dayIt.hasNext()) {
            JsonNode day = dayIt.next();
            Date createdAt = toDate(day.get("created_at").asText());
            JsonNode trendNodes = day.get("trends");
            List<Trend> trends = new ArrayList<Trend>();
            for (Iterator<JsonNode> trendsIt = trendNodes.iterator(); trendsIt.hasNext();) {
                JsonNode trendNode = trendsIt.next();
                trends.add(new Trend(trendNode.get("name").asText(), trendNode.get("query").textValue()));
            }
            jp.skipChildren();
            return new LocalTrendsHolder(new Trends(createdAt, trends));
        }

        throw ctxt.mappingException(LocalTrendsHolder.class);
    }

    private static final String LOCAL_TREND_DATE_FORMAT = "yyyy-mm-dd'T'HH:mm:ss'Z'";

    private static Date toDate(String dateString) {
        try {
            return new SimpleDateFormat(LOCAL_TREND_DATE_FORMAT).parse(dateString);
        } catch (ParseException e) {
            return null;
        }
    }
}