de.taimos.gpsd4java.backend.AbstractResultParser.java Source code

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Here is the source code for de.taimos.gpsd4java.backend.AbstractResultParser.java

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package de.taimos.gpsd4java.backend;

/*
 * #%L
 * GPSd4Java
 * %%
 * Copyright (C) 2011 - 2012 Taimos 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.
 * #L%
 */

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.TimeZone;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import de.taimos.gpsd4java.types.IGPSObject;
import de.taimos.gpsd4java.types.ParseException;

/**
 * 
 * @author irakli, thoeger
 */
public abstract class AbstractResultParser {

    protected static final Logger LOG = LoggerFactory.getLogger(ResultParser.class);

    protected final DateFormat dateFormat; // Don't make this static!

    /**
     * Create new ResultParser
     */
    public AbstractResultParser() {
        this.dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
        this.dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
    }

    /**
     * Parse a received line into a {@link IGPSObject}
     * 
     * @param line
     *            the line read from GPSd
     * @return the parsed object
     * @throws ParseException
     *             if parsing fails
     */
    public IGPSObject parse(final String line) throws ParseException {
        try {
            final JSONObject json = new JSONObject(line);
            return this.parse(json);
        } catch (final JSONException e) {
            throw new ParseException("Parsing failed", e);
        }
    }

    /**
     * @param json
     * @return the parsed {@link IGPSObject}
     * @throws ParseException
     */
    public abstract IGPSObject parse(final JSONObject json) throws ParseException;

    /**
     * parse a whole JSONArray into a list of IGPSObjects
     */
    @SuppressWarnings({ "unchecked", "unused" })
    protected <T extends IGPSObject> List<T> parseObjectArray(final JSONArray array, final Class<T> type)
            throws ParseException {
        try {
            if (array == null) {
                return new ArrayList<T>(10);
            }
            final List<T> objects = new ArrayList<T>(10);
            for (int i = 0; i < array.length(); i++) {
                objects.add((T) this.parse(array.getJSONObject(i)));
            }
            return objects;
        } catch (final JSONException e) {
            throw new ParseException("Parsing failed", e);
        }
    }

    protected double parseTimestamp(final JSONObject json, final String fieldName) {
        try {
            final String text = json.optString(fieldName, null);
            AbstractResultParser.LOG.debug(fieldName + ": {}", text);

            if (text != null) {
                final Date date = this.dateFormat.parse(text);
                if (AbstractResultParser.LOG.isDebugEnabled()) {
                    final String ds = DateFormat.getDateTimeInstance(DateFormat.FULL, DateFormat.FULL).format(date);
                    AbstractResultParser.LOG.debug("Date: {}", ds);
                }
                return date.getTime() / 1000.0;
            }
        } catch (final Exception ex) {
            AbstractResultParser.LOG.info("Failed to parse time", ex);
        }
        return Double.NaN;
    }
}