How to parse and plot gpx file has an android MapView

I'm work开发者_运维问答ing to implement MapView for the given gpx file to show way points and tracks,please any one guide me to implement it with sample code.

Thanks in advance.

It is working correctly

package com.lightcone.mapoverlaydemo;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserFactory;

import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.View;
import android.view.Window;
import android.view.View.OnClickListener;
import android.widget.Button;

import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import com.google.android.maps.OverlayItem;

public class ShowTheMap extends MapActivity {

    private static double lat;
    private static double lon;
    private int latE6;
    private int lonE6;
    private MapController mapControl;
    private GeoPoint gp;
    private MapView mapView;

    private Button overlayButton, accessButton;
    private Button routeButton;
    private List<Overlay> mapOverlays;
    private Drawable drawable1, drawable2;
    private MyItemizedOverlay itemizedOverlay1, itemizedOverlay2;
    private boolean foodIsDisplayed = false;

    // Define an array containing the food overlay items

    private OverlayItem[] foodItem = {
            new OverlayItem(new GeoPoint(35952967, -83929158), "Food Title 1",
                    "Food snippet 1"),
            new OverlayItem(new GeoPoint(35953000, -83928000), "Food Title 2",
                    "Food snippet 2"),
            new OverlayItem(new GeoPoint(35955000, -83929158), "Food Title 3",
                    "Food snippet 3") };

    // Define an array containing the access overlay items

    private OverlayItem[] accessItem = {
            new OverlayItem(new GeoPoint(35953700, -83926158),
                    "Access Title 1", "Access snippet 1"),
            new OverlayItem(new GeoPoint(35954000, -83928200),
                    "Access Title 2", "Access snippet 2"),
            new OverlayItem(new GeoPoint(35955000, -83927558),
                    "Access Title 3", "Access snippet 3"),
            new OverlayItem(new GeoPoint(35954000, -83927158),
                    "Access Title 4", "Access snippet 4") };

    String TAG = "GPStest";
    // Set up the array of GeoPoints defining the route
    int numberRoutePoints;
    GeoPoint routePoints[]; // Dimension will be set in class RouteLoader below
    int routeGrade[]; // Index for slope of route from point i to point i+1
    RouteSegmentOverlay route; // This will hold the route segments
    boolean routeIsDisplayed = false;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE); // Suppress title bar for
                                                        // more space
        setContentView(R.layout.showthemap);

        // Add map controller with zoom controls
        mapView = (MapView) findViewById(R.id.mv);
        mapView.setSatellite(false);
        mapView.setTraffic(false);
        mapView.setBuiltInZoomControls(true); // Set android:clickable=true in
                                                // main.xml
        int maxZoom = mapView.getMaxZoomLevel();
        int initZoom = maxZoom - 2;
        mapControl = mapView.getController();
        mapControl.setZoom(initZoom);
        // Convert lat/long in degrees into integers in microdegrees
        latE6 = (int) (35.955 * 1e6);
        lonE6 = (int) (-83.9265 * 1e6);
        gp = new GeoPoint(latE6, lonE6);
        mapControl.animateTo(gp);

        // // Button to control food overlay
        // overlayButton = (Button)findViewById(R.id.doOverlay);
        // overlayButton.setOnClickListener(new OnClickListener(){
        // public void onClick(View v) {
        // setOverlay1();
        // }
        // });
        //      
        // // Button to control access overlay
        // accessButton = (Button)findViewById(R.id.doAccess);
        // accessButton.setOnClickListener(new OnClickListener(){
        // public void onClick(View v) {
        // setOverlay2();
        // }
        // });

        // Button to control route overlay
        routeButton = (Button) findViewById(R.id.doRoute);
        routeButton.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                if (!routeIsDisplayed) {
                    routeIsDisplayed = true;
                    loadRouteData();
                } else {
                    if (route != null)
                        route.setRouteView(false);
                    route = null; // To prevent multiple route instances if key
                                    // toggled rapidly (see line 235)
                    routeIsDisplayed = false;
                    mapView.postInvalidate();
                }
            }
        });

    }

    /*
     * Methods to set map overlays. In this case we will place a small overlay
     * image at a specified location. Place the marker image as a png file in
     * res > drawable-* . For example, the reference to
     * R.drawable.knifefork_small below is to an image file called
     * knifefork_small.png in the project folder res > drawable-hdpi. Can only
     * use lower case letters a-z, numbers 0-9, ., and _ in these image file
     * names. In this example the single overlay item is specified by drawable
     * and the location of the overlay item is specified by overlayitem.
     */

    // Display food location overlay. If not already displayed, clicking button
    // displays all
    // food overlays. If already displayed successive clicks remove items one by
    // one. This
    // illustrates ability to change individual overlay items dynamically at
    // runtime.

    public void setOverlay1() {
        int foodLength = foodItem.length;
        // Create itemizedOverlay2 if it doesn't exist and display all three
        // items
        if (!foodIsDisplayed) {
            mapOverlays = mapView.getOverlays();
            drawable1 = this.getResources().getDrawable(
                    R.drawable.knifefork_small);
            itemizedOverlay1 = new MyItemizedOverlay(drawable1);
            // Display all three items at once
            for (int i = 0; i < foodLength; i++) {
                itemizedOverlay1.addOverlay(foodItem[i]);
            }
            mapOverlays.add(itemizedOverlay1);
            foodIsDisplayed = !foodIsDisplayed;
            // Remove each item successively with button clicks
        } else {
            itemizedOverlay1.removeItem(itemizedOverlay1.size() - 1);
            if ((itemizedOverlay1.size() < 1))
                foodIsDisplayed = false;
        }
        // Added symbols will be displayed when map is redrawn so force redraw
        // now
        mapView.postInvalidate();
    }

    // Display accessibility overlay. If not already displayed, successive
    // button clicks display each of
    // the three icons successively, then the next removes them all. This
    // illustrates the ability to
    // change individual overlay items dynamically at runtime.

    public void setOverlay2() {
        int accessLength = accessItem.length;
        // Create itemizedOverlay2 if it doesn't exist
        if (itemizedOverlay2 == null) {
            mapOverlays = mapView.getOverlays();
            drawable2 = this.getResources().getDrawable(
                    R.drawable.accessibility);
            itemizedOverlay2 = new MyItemizedOverlay(drawable2);
        }
        // Add items with each click
        if (itemizedOverlay2.size() < accessLength) {
            itemizedOverlay2.addOverlay(accessItem[itemizedOverlay2.size()]);
            mapOverlays.add(itemizedOverlay2);
            // Remove all items with one click
        } else {
            for (int i = 0; i < accessLength; i++) {
                itemizedOverlay2.removeItem(accessLength - 1 - i);
            }
        }
        // Added symbols will be displayed when map is redrawn so force redraw
        // now
        mapView.postInvalidate();
    }

    // Method to insert latitude and longitude in degrees
    public static void putLatLong(double latitude, double longitude) {
        lat = latitude;
        lon = longitude;
    }

    // This sets the s key on the phone to toggle between satellite and map view
    // and the t key to toggle between traffic and no traffic view (traffic view
    // relevant only in urban areas where it is reported).

    public boolean onKeyDown(int keyCode, KeyEvent e) {
        if (keyCode == KeyEvent.KEYCODE_S) {
            mapView.setSatellite(!mapView.isSatellite());
            return true;
        } else if (keyCode == KeyEvent.KEYCODE_T) {
            mapView.setTraffic(!mapView.isTraffic());
            mapControl.animateTo(gp); // To ensure change displays immediately
        }
        return (super.onKeyDown(keyCode, e));
    }

    // Required method since class extends MapActivity
    @Override
    protected boolean isRouteDisplayed() {
        return false; // Don't display a route
    }

    // Method to read route data from server as XML

    public void loadRouteData() {
        try {
            String url = "http://eagle.phys.utk.edu/reubendb/UTRoute.php";
            String data = "?lat1=35952967&lon1=-83929158&lat2=35956567&lon2=-83925450";
            // RouteLoader RL = new RouteLoader();
            // RL.execute(new URL(url+data));
            new RouteLoader().execute(new URL(url + data));
        } catch (MalformedURLException e) {
            Log.i("NETWORK", "Failed to generate valid URL");
        }
    }

    // Overlay a route. This method is only executed after loadRouteData()
    // completes
    // on background thread.

    public void overlayRoute() {
        if (route != null)
            return; // To prevent multiple route instances if key toggled
                    // rapidly (see also line 116)
        // Set up the overlay controller
        route = new RouteSegmentOverlay(routePoints, routeGrade); // My class
                                                                    // defining
                                                                    // route
                                                                    // overlay
        mapOverlays = mapView.getOverlays();
        mapOverlays.add(route);

        // Added symbols will be displayed when map is redrawn so force redraw
        // now
        mapView.postInvalidate();
    }

    /*
     * Class to implement single task on background thread without having to
     * manage the threads directly. Launch with
     * "new RouteLoader().execute(new URL(urlString)". Must be launched from the
     * UI thread and may only be invoked once. Adapted from example in Ch. 10 of
     * Android Wireless Application Development. Use this to do data load from
     * network on separate thread from main user interface to prevent locking
     * main UI if there is network delay.
     */

    private class RouteLoader extends AsyncTask<URL, String, String> {

        @Override
        protected String doInBackground(URL... params) {
            // This pattern takes more than one param but we'll just use the
            // first
            try {
                URL text = params[0];

                XmlPullParserFactory parserCreator;

                parserCreator = XmlPullParserFactory.newInstance();

                XmlPullParser parser = parserCreator.newPullParser();

                // parser.setInput(text.openStream(), null);
                parser.setInput(getResources()
                        .openRawResource(R.raw.fells_loop), null);

                publishProgress("Parsing XML...");

                int parserEvent = parser.getEventType();
                int pointCounter = -1;
                int wptCounter = -1;
                int totalWaypoints = -1;
                int lat = -1;
                int lon = -1;
                String wptDescription = "";
                int grade = -1;

                // Parse the XML returned on the network
                while (parserEvent != XmlPullParser.END_DOCUMENT) {
                    switch (parserEvent) {
                    case XmlPullParser.START_TAG:
                        String tag = parser.getName();
                        if (tag.compareTo("number") == 0) {
                            numberRoutePoints = Integer.parseInt(parser
                                    .getAttributeValue(null, "numpoints"));
                            totalWaypoints = Integer.parseInt(parser
                                    .getAttributeValue(null, "numwpts"));
                            routePoints = new GeoPoint[numberRoutePoints];
                            routeGrade = new int[numberRoutePoints];
                            Log.i(TAG, "   Total points = " + numberRoutePoints
                                    + " Total waypoints = " + totalWaypoints);
                        }
                        if (tag.compareTo("trkpt") == 0) {
                            pointCounter++;
                            lat = Integer.parseInt(parser.getAttributeValue(
                                    null, "lat"));
                            lon = Integer.parseInt(parser.getAttributeValue(
                                    null, "lon"));
                            grade = Integer.parseInt(parser.getAttributeValue(
                                    null, "grade"));
                            routePoints[pointCounter] = new GeoPoint(lat, lon);
                            routeGrade[pointCounter] = grade;
                            Log.i(TAG, "   trackpoint=" + pointCounter
                                    + " latitude=" + lat + " longitude=" + lon
                                    + " grade=" + grade);
                        } else if (tag.compareTo("wpt") == 0) {
                            wptCounter++;
                            lat = Integer.parseInt(parser.getAttributeValue(
                                    null, "lat"));
                            lon = Integer.parseInt(parser.getAttributeValue(
                                    null, "lon"));
                            wptDescription = parser.getAttributeValue(null,
                                    "description");
                            Log.i(TAG, "   waypoint=" + wptCounter
                                    + " latitude=" + lat + " longitude=" + lon
                                    + " " + wptDescription);
                        }
                        break;
                    }

                    parserEvent = parser.next();
                }

            } catch (Exception e) {
                Log.i("RouteLoader", "Failed in parsing XML", e);
                return "Finished with failure.";
            }

            return "Done...";
        }

        protected void onCancelled() {
            Log.i("RouteLoader", "GetRoute task Cancelled");
        }

        // Now that route data are loaded, execute the method to overlay the
        // route on the map
        protected void onPostExecute(String result) {
            Log.i(TAG, "Route data transfer complete");
            overlayRoute();
        }

        protected void onPreExecute() {
            Log.i(TAG, "Ready to load URL");
        }

        protected void onProgressUpdate(String... values) {
            super.onProgressUpdate(values);
        }

    }

}

feel_loop.xml file content from raw folder

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<gpx
 version="1.0"
 creator="ExpertGPS 1.1.1 - http://www.topografix.com"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns="http://www.topografix.com/GPX/1/0"
 xmlns:topografix="http://www.topografix.com/GPX/Private/TopoGrafix/0/1"
 xsi:schemaLocation="http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd http://www.topografix.com/GPX/Private/TopoGrafix/0/1 http://www.topografix.com/GPX/Private/TopoGrafix/0/1/topografix.xsd">
  <number numpoints="23" numwpts="2"></number>
  <wpt lat="35952967" lon="-83929158" description="Construction"></wpt>
  <wpt lat="35955038" lon="-83929126" description="Heavy traffic"></wpt>
  <trk>
    <trkseg>
        <trkpt lat="35952967" lon="-83929158" grade="1"></trkpt>
        <trkpt lat="35954021" lon="-83930341" grade="1"></trkpt>
        <trkpt lat="35954951" lon="-83929075" grade="1"></trkpt>

        <trkpt lat="35955038" lon="-83929126" grade="4"></trkpt>
        <trkpt lat="35955203" lon="-83928973" grade="1"></trkpt>
        <trkpt lat="35955212" lon="-83928855" grade="1"></trkpt>
        <trkpt lat="35955603" lon="-83928273" grade="2"></trkpt>
        <trkpt lat="35955807" lon="-83928369" grade="1"></trkpt>
        <trkpt lat="35955974" lon="-83927943" grade="1"></trkpt>
        <trkpt lat="35956063" lon="-83927720" grade="1"></trkpt>
        <trkpt lat="35956291" lon="-83927358" grade="1"></trkpt>
        <trkpt lat="35956471" lon="-83927229" grade="1"></trkpt>

        <trkpt lat="35956541" lon="-83927176" grade="2"></trkpt>
        <trkpt lat="35956397" lon="-83927044" grade="3"></trkpt>
        <trkpt lat="35956274" lon="-83926685" grade="1"></trkpt>
        <trkpt lat="35956213" lon="-83926642" grade="1"></trkpt>
        <trkpt lat="35956239" lon="-83926261" grade="1"></trkpt>
        <trkpt lat="35956202" lon="-83925722" grade="1"></trkpt>
        <trkpt lat="35956226" lon="-83925467" grade="1"></trkpt>
        <trkpt lat="35956343" lon="-83925502" grade="1"></trkpt>
        <trkpt lat="35956324" lon="-83925617" grade="1"></trkpt>

        <trkpt lat="35956445" lon="-83925379" grade="1"></trkpt>
        <trkpt lat="35956567" lon="-83925450" grade="1"></trkpt>
    </trkseg>
  </trk>
</gpx>

Building on Kandha's answer, for the actual GPX parsing you can easily use one of the existing libraries to do it. See this other StackOverflow question.