lunedì 2 aprile 2012

Leggere file GPX in Android


Un esempio di come usare la classe java scaricabile qui per leggere i file gpx su Android


package com.gpx;


import android.app.Activity;


import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Iterator;


import java.util.List;


import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;


import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;


import android.location.Location;


import android.os.Bundle;
import android.util.Log;


class GpxReader
{
private static final SimpleDateFormat gpxDate = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");


public static List<Location> getPoints(File gpxFile)
{
    List<Location> points = null;
    try
    {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();


        FileInputStream fis = new FileInputStream(gpxFile);
        Document dom = builder.parse(fis);
        Element root = dom.getDocumentElement();
        NodeList items = root.getElementsByTagName("trkpt");


        points = new ArrayList<Location>();


        for(int j = 0; j < items.getLength(); j++)
        {
            Node item = items.item(j);
            NamedNodeMap attrs = item.getAttributes();
            NodeList props = item.getChildNodes();


            Location pt = new Location("test");


            pt.setLatitude(Double.parseDouble(attrs.getNamedItem("lat").getTextContent()));
            pt.setLongitude(Double.parseDouble(attrs.getNamedItem("lon").getTextContent()));


            for(int k = 0; k<props.getLength(); k++)
            {
                Node item2 = props.item(k);
                String name = item2.getNodeName();
                if(!name.equalsIgnoreCase("time")) continue;
                try
                {
                    pt.setTime((getDateFormatter().parse(item2.getFirstChild().getNodeValue())).getTime());
                }


                catch(ParseException ex)
                {
                    ex.printStackTrace();
                }
            }


            for(int y = 0; y<props.getLength(); y++)
            {
                Node item3 = props.item(y);
                String name = item3.getNodeName();
                if(!name.equalsIgnoreCase("ele")) continue;
                pt.setAltitude(Double.parseDouble(item3.getFirstChild().getNodeValue()));
            }


            points.add(pt);


        }


        fis.close();
    }


    catch(FileNotFoundException e)
    {
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }


    catch(ParserConfigurationException ex)
    {


    }


    catch (SAXException ex) {
    }


    return points;
}


public static SimpleDateFormat getDateFormatter()
  {
    return (SimpleDateFormat)gpxDate.clone();
  }


}






public class GpxActivity extends Activity {
    private List<Location> t;
private double lat;
private double lon;
private double alt;


/** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        File gpx = new File("/mnt/sdcard/malandrino.gpx");
        t = GpxReader.getPoints(gpx);
        Iterator<Location> it = t.iterator();
        while (it.hasNext())
        {
        Location value =  it.next();
        lat = value.getLatitude();
        lon = value.getLongitude();
        alt = value.getAltitude();
        Log.d("gpx",Double.toString(lat));
        Log.d("gpx",Double.toString(lon));
        Log.d("gpx",Double.toString(alt));
        }
    }
}

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