org.hbird.business.celestrack.http.CelestrackReader.java Source code

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Here is the source code for org.hbird.business.celestrack.http.CelestrackReader.java

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/**
 * Licensed to the Hummingbird Foundation (HF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The HF licenses this file to You 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.hbird.business.celestrack.http;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.ProxySelector;

import org.apache.camel.Handler;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.conn.params.ConnRoutePNames;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.ProxySelectorRoutePlanner;
import org.hbird.business.api.ICatalogue;
import org.hbird.business.api.IPublisher;
import org.hbird.business.celestrack.CelestrackComponent;
import org.hbird.exchange.navigation.Satellite;
import org.hbird.exchange.navigation.TleOrbitalParameters;

/**
 * Bean to access the Celestrack website and pull TLE specifications.
 * 
 * @author Gert Villemos
 * 
 */
public class CelestrackReader {

    /** The logger. */
    private static final Log LOG = LogFactory.getLog(CelestrackReader.class);

    /** The HTTP client used to access the remote URL */
    protected DefaultHttpClient client = new DefaultHttpClient();

    /** The Part that this bean is the implementation of. Holds the configuration variables. */
    protected CelestrackComponent part = null;

    private IPublisher publisher;
    private ICatalogue catalogue;

    /**
     * Constructor registering the Part that this bean is implementing.
     * 
     * @param part The part that this bean is the implementation of
     */
    public CelestrackReader(CelestrackComponent part, IPublisher publisher, ICatalogue catalogue) {
        this.part = part;
        this.publisher = publisher;
        this.catalogue = catalogue;
    }

    /**
     * Method to access the Celestrack website, download the TLE file ('elements'), extract the TLEs and
     * publish them to the system.
     * 
     * @return 0 (always)
     * @throws Exception
     */
    @Handler
    public int read() throws Exception {

        if (part.getProxyHost() != null) {
            HttpHost proxy = new HttpHost(part.getProxyHost(), part.getProxyPort());
            client.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy);
        } else {
            ProxySelectorRoutePlanner routePlanner = new ProxySelectorRoutePlanner(
                    client.getConnectionManager().getSchemeRegistry(), ProxySelector.getDefault());
            client.setRoutePlanner(routePlanner);
        }

        long now = System.currentTimeMillis();

        for (String uri : part.getElements().split(":")) {
            HttpResponse response = client
                    .execute(new HttpGet("http://www.celestrak.com/NORAD/elements/" + uri + ".txt"));

            if (response.getStatusLine().getStatusCode() == 200) {
                String text = readFully(response.getEntity().getContent());
                String elements[] = text.split("\n");

                for (int index = 0; index < elements.length; index += 3) {
                    Satellite satellite = null;
                    String name = elements[index].trim();
                    Object object = catalogue.getSatelliteByName(name);
                    if (object == null) {
                        /* Satellite unknown. Create placeholder object. */
                        // TODO - 18.05.2013, kimmell - create proper entity ID here
                        String entityID = name;
                        satellite = new Satellite(entityID, name);
                        publisher.publish(satellite);
                    } else {
                        satellite = (Satellite) object;
                    }

                    TleOrbitalParameters parameters = new TleOrbitalParameters(satellite.getID() + "/TLE",
                            TleOrbitalParameters.class.getSimpleName());
                    parameters.setSatelliteId(satellite.getID());
                    parameters.setTleLine1(elements[index + 1].trim());
                    parameters.setTleLine2(elements[index + 2].trim());
                    publisher.publish(parameters);
                }
            }
        }

        return 0;
    }

    /**
     * Helper method to read a HTML byte stream returned through
     * 
     * @param input The input stream
     * @return A string of the complete data
     * @throws IOException
     */
    protected static String readFully(InputStream input) throws IOException {

        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(input));
        StringBuffer result = new StringBuffer();
        char[] buffer = new char[4 * 1024];
        int charsRead;
        while ((charsRead = bufferedReader.read(buffer)) != -1) {
            result.append(buffer, 0, charsRead);
        }
        input.close();
        bufferedReader.close();

        return result.toString();
    }
}