GeoNamesPOIProvider.java

package org.osmdroid.location;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Locale;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.oscim.core.BoundingBox;
import org.oscim.core.GeoPoint;
import org.osmdroid.utils.BonusPackHelper;
import org.osmdroid.utils.HttpConnection;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import android.util.Log;

/**
 * POI Provider using GeoNames services. Currently, "find Nearby Wikipedia" and
 * "Wikipedia Articles in Bounding Box" services.
 * @see "http://www.geonames.org"
 * @author M.Kergall
 */
public class GeoNamesPOIProvider {

	protected String mUserName;

	/**
	 * @param account
	 *            the registered "username" to give to GeoNames service.
	 * @see "http://www.geonames.org/login"
	 */
	public GeoNamesPOIProvider(String account) {
		mUserName = account;
	}

	private String getUrlCloseTo(GeoPoint p, int maxResults, double maxDistance) {
		StringBuffer url = new StringBuffer("http://api.geonames.org/findNearbyWikipediaJSON?");
		url.append("lat=" + p.getLatitude());
		url.append("&lng=" + p.getLongitude());
		url.append("&maxRows=" + maxResults);
		url.append("&radius=" + maxDistance); //km
		url.append("&lang=" + Locale.getDefault().getLanguage());
		url.append("&username=" + mUserName);
		return url.toString();
	}

	private String getUrlInside(BoundingBox boundingBox, int maxResults) {
		StringBuffer url = new StringBuffer("http://api.geonames.org/wikipediaBoundingBoxJSON?");
		url.append("south=" + boundingBox.getMinLatitude());
		url.append("&north=" + boundingBox.getMaxLatitude());
		url.append("&west=" + boundingBox.getMinLongitude());
		url.append("&east=" + boundingBox.getMaxLongitude());
		url.append("&maxRows=" + maxResults);
		url.append("&lang=" + Locale.getDefault().getLanguage());
		url.append("&username=" + mUserName);
		return url.toString();
	}

	/**
	 * @param fullUrl
	 *            ...
	 * @return the list of POI
	 */
	public ArrayList<POI> getThem(String fullUrl) {
		Log.d(BonusPackHelper.LOG_TAG, "GeoNamesPOIProvider:get:" + fullUrl);
		String jString = BonusPackHelper.requestStringFromUrl(fullUrl);
		if (jString == null) {
			Log.e(BonusPackHelper.LOG_TAG, "GeoNamesPOIProvider: request failed.");
			return null;
		}
		try {
			JSONObject jRoot = new JSONObject(jString);
			JSONArray jPlaceIds = jRoot.getJSONArray("geonames");
			int n = jPlaceIds.length();
			ArrayList<POI> pois = new ArrayList<POI>(n);
			for (int i = 0; i < n; i++) {
				JSONObject jPlace = jPlaceIds.getJSONObject(i);
				POI poi = new POI(POI.POI_SERVICE_GEONAMES_WIKIPEDIA);
				poi.location = new GeoPoint(jPlace.getDouble("lat"),
						jPlace.getDouble("lng"));
				poi.category = jPlace.optString("feature");
				poi.type = jPlace.getString("title");
				poi.description = jPlace.optString("summary");
				poi.thumbnailPath = jPlace.optString("thumbnailImg", null);
				/* This makes loading too long. Thumbnail loading will be done
				 * only when needed, with POI.getThumbnail() if
				 * (poi.mThumbnailPath != null){ poi.mThumbnail =
				 * BonusPackHelper.loadBitmap(poi.mThumbnailPath); } */
				poi.url = jPlace.optString("wikipediaUrl", null);
				if (poi.url != null)
					poi.url = "http://" + poi.url;
				poi.rank = jPlace.optInt("rank", 0);
				//other attributes: distance?
				pois.add(poi);
			}
			Log.d(BonusPackHelper.LOG_TAG, "done");
			return pois;
		} catch (JSONException e) {
			e.printStackTrace();
			return null;
		}
	}

	//XML parsing seems 2 times slower than JSON parsing
	public ArrayList<POI> getThemXML(String fullUrl) {
		Log.d(BonusPackHelper.LOG_TAG, "GeoNamesPOIProvider:get:" + fullUrl);
		HttpConnection connection = new HttpConnection();
		connection.doGet(fullUrl);
		InputStream stream = connection.getStream();
		if (stream == null) {
			return null;
		}
		GeoNamesXMLHandler handler = new GeoNamesXMLHandler();
		try {
			SAXParser parser = SAXParserFactory.newInstance().newSAXParser();
			parser.parse(stream, handler);
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		connection.close();
		Log.d(BonusPackHelper.LOG_TAG, "done");
		return handler.mPOIs;
	}

	/**
	 * @param position
	 *            ...
	 * @param maxResults
	 *            ...
	 * @param maxDistance
	 *            ... in km. 20 km max for the free service.
	 * @return list of POI, Wikipedia entries close to the position. Null if
	 *         technical issue.
	 */
	public ArrayList<POI> getPOICloseTo(GeoPoint position,
			int maxResults, double maxDistance) {
		String url = getUrlCloseTo(position, maxResults, maxDistance);
		return getThem(url);
	}

	/**
	 * @param boundingBox
	 *            ...
	 * @param maxResults
	 *            ...
	 * @return list of POI, Wikipedia entries inside the bounding box. Null if
	 *         technical issue.
	 */
	public ArrayList<POI> getPOIInside(BoundingBox boundingBox, int maxResults) {
		String url = getUrlInside(boundingBox, maxResults);
		return getThem(url);
	}
}

class GeoNamesXMLHandler extends DefaultHandler {

	private String mString;
	double mLat, mLng;
	POI mPOI;
	ArrayList<POI> mPOIs;

	public GeoNamesXMLHandler() {
		mPOIs = new ArrayList<POI>();
	}

	@Override
	public void startElement(String uri, String localName, String name,
			Attributes attributes) {
		if (localName.equals("entry")) {
			mPOI = new POI(POI.POI_SERVICE_GEONAMES_WIKIPEDIA);
		}
		mString = new String();
	}

	@Override
	public void characters(char[] ch, int start, int length) {
		String chars = new String(ch, start, length);
		mString = mString.concat(chars);
	}

	@Override
	public void endElement(String uri, String localName, String name) {
		if (localName.equals("lat")) {
			mLat = Double.parseDouble(mString);
		} else if (localName.equals("lng")) {
			mLng = Double.parseDouble(mString);
		} else if (localName.equals("feature")) {
			mPOI.category = mString;
		} else if (localName.equals("title")) {
			mPOI.type = mString;
		} else if (localName.equals("summary")) {
			mPOI.description = mString;
		} else if (localName.equals("thumbnailImg")) {
			if (mString != null && !mString.equals(""))
				mPOI.thumbnailPath = mString;
		} else if (localName.equals("wikipediaUrl")) {
			if (mString != null && !mString.equals(""))
				mPOI.url = "http://" + mString;
		} else if (localName.equals("rank")) {
			mPOI.rank = Integer.parseInt(mString);
		} else if (localName.equals("entry")) {
			mPOI.location = new GeoPoint(mLat, mLng);
			mPOIs.add(mPOI);
		}
	}

}