org.envirocar.aggregation.AggregatedTracksServlet.java Source code

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Here is the source code for org.envirocar.aggregation.AggregatedTracksServlet.java

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/**
 * Copyright 2014 52North Initiative for Geospatial Open Source
 * Software 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.envirocar.aggregation;

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.nio.charset.Charset;
import java.sql.Date;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.TimeZone;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.envirocar.analyse.postgres.PostgresConnection;
import org.envirocar.analyse.properties.Properties;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.google.inject.Singleton;

@Singleton
public class AggregatedTracksServlet extends HttpServlet {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private static final String AGGREGATION_DATE = "aggregation_date";
    public static final String PATH = "/aggregatedTracks";
    private PostgresConnection connection;
    private String aggregatedTracksTableName;
    private String query;
    private SimpleDateFormat df;
    private ObjectMapper om;
    private String trackQuery;

    @Override
    public void init() throws ServletException {
        super.init();

        this.connection = new PostgresConnection();

        this.aggregatedTracksTableName = (String) Properties.getProperty("aggregatedTracksTableName");
        this.query = "SELECT * FROM " + this.aggregatedTracksTableName + " ORDER BY id DESC LIMIT 100";
        this.trackQuery = "SELECT * FROM " + this.aggregatedTracksTableName + " WHERE id = '%s'";

        TimeZone tz = TimeZone.getTimeZone("UTC");
        df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
        df.setTimeZone(tz);

        om = new ObjectMapper();
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        OutputStreamWriter writer = new OutputStreamWriter(resp.getOutputStream(), Charset.forName("UTF-8"));

        resp.setContentType("application/json");

        String uri = req.getRequestURI();
        String subPath = uri.substring(uri.indexOf(PATH) + PATH.length());

        String trackId = null;
        if (!subPath.isEmpty() && !(subPath.length() == 1 && subPath.equals("/"))) {
            trackId = subPath.startsWith("/") ? subPath.substring(1) : subPath;
        }

        String json;
        try {
            if (trackId != null) {
                json = createTrackExists(trackId);
            } else {
                json = createAggregatedTracksList();
            }
        } catch (SQLException e) {
            throw new IOException(e);
        }

        writer.append(json);

        writer.flush();
        writer.close();

        resp.setStatus(200);
    }

    private String createTrackExists(String trackId) throws SQLException {
        ResultSet rs = this.connection.executeQueryStatement(String.format(trackQuery, trackId));

        ObjectNode result = om.createObjectNode();

        result.put("aggregated", rs.next());

        rs.close();

        return result.toString();
    }

    private String createAggregatedTracksList() throws SQLException {
        ResultSet rs = this.connection.executeQueryStatement(query);

        ArrayNode array = om.createArrayNode();
        ObjectNode object;
        String id;
        Timestamp ts;
        while (rs.next()) {
            object = om.createObjectNode();
            id = rs.getString("id");
            ts = rs.getTimestamp(AGGREGATION_DATE);

            object.put(id, df.format(new Date(ts.getTime())));

            array.add(object);
        }

        rs.close();

        ObjectNode node = om.createObjectNode();

        node.put("tracks", array);
        return node.toString();
    }

}