GoogleMapsAPI.java

package uni.projecte.maps;

import java.io.IOException;
import java.io.InputStream;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;

public class GoogleMapsAPI {
	
	
	public double getElevationFromGoogleMaps(double longitude, double latitude) {
        double result = Double.NaN;
        HttpClient httpClient = new DefaultHttpClient();
        HttpContext localContext = new BasicHttpContext();
        String url = "http://maps.googleapis.com/maps/api/elevation/"
                + "xml?locations=" + String.valueOf(longitude)
                + "," + String.valueOf(latitude)
                + "&sensor=true";
        HttpGet httpGet = new HttpGet(url);
        try {
            HttpResponse response = httpClient.execute(httpGet, localContext);
            HttpEntity entity = response.getEntity();
            if (entity != null) {
                InputStream instream = entity.getContent();
                int r = -1;
                StringBuffer respStr = new StringBuffer();
                while ((r = instream.read()) != -1)
                    respStr.append((char) r);
                String tagOpen = "<elevation>";
                String tagClose = "</elevation>";
                if (respStr.indexOf(tagOpen) != -1) {
                    int start = respStr.indexOf(tagOpen) + tagOpen.length();
                    int end = respStr.indexOf(tagClose);
                    String value = respStr.substring(start, end);
                   // result = (double)(Double.parseDouble(value)*3.2808399); // convert from meters to feet
                    result = Double.parseDouble(value); // convert from meters to feet

                    
                }
                instream.close();
            }
        } catch (ClientProtocolException e) {} 
        catch (IOException e) {}

        return result;
    }
	
	public double getAltitudeFromGISData(Double longitude, Double latitude) {
	    double result = Double.NaN;
	    HttpClient httpClient = new DefaultHttpClient();
	    HttpContext localContext = new BasicHttpContext();
	    String url = "http://gisdata.usgs.gov/"
	            + "xmlwebservices2/elevation_service.asmx/"
	            + "getElevation?X_Value=" + String.valueOf(longitude)
	            + "&Y_Value=" + String.valueOf(latitude)
	            + "&Elevation_Units=METERS&Source_Layer=-1&Elevation_Only=true";
	    HttpGet httpGet = new HttpGet(url);
	    try {
	        HttpResponse response = httpClient.execute(httpGet, localContext);
	        HttpEntity entity = response.getEntity();
	        if (entity != null) {
	            InputStream instream = entity.getContent();
	            int r = -1;
	            StringBuffer respStr = new StringBuffer();
	            while ((r = instream.read()) != -1)
	                respStr.append((char) r);
	            String tagOpen = "<double>";
	            String tagClose = "</double>";
	            if (respStr.indexOf(tagOpen) != -1) {
	                int start = respStr.indexOf(tagOpen) + tagOpen.length();
	                int end = respStr.indexOf(tagClose);
	                String value = respStr.substring(start, end);
	                result = Double.parseDouble(value);
	            }
	            instream.close();
	        }
	    } catch (ClientProtocolException e) {} 
	    catch (IOException e) {}
	    return result;
	}



}