谷歌地圖上的精確路徑

Question

我有一個複雜的谷歌地圖問題。我使用的是android和我繪製了2個具體點之間的路徑，但問題是路徑不準確，因爲它在可逆的街道上繪製，所以路徑現在是不對的任何人都可以有任何想法如何忽略錯誤的街道？

Answer 1

這是工作示例link。一探究竟。它有助於在地圖上創建路線覆蓋圖。這裏是complete source code。

編輯： 爲亞歷山德羅以下提到：「這種方法，使用KML似乎沒有提供任何更多，這個問題已經在最後的日子＃2討論Google Maps output=kml broken?」

Answer 2

使用下面的類代碼::

import java.io.IOException; 
import java.net.HttpURLConnection; 
import java.net.MalformedURLException; 
import java.net.URL; 
import java.util.ArrayList; 
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.Node; 
import org.w3c.dom.NodeList; 
import org.xml.sax.SAXException; 

import android.graphics.Color; 
import android.graphics.drawable.Drawable; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.util.Log; 

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



public class RoutePath extends MapActivity { 
    /** Called when the activity is first created. */ 

    MapView mapView; 
    private RoutePath _activity; 

    GeoPoint srcGeoPoint,destGeoPoint; 
    private static List<Overlay> mOverlays; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 
     _activity = this; 

     MapView mapView = (MapView) findViewById(R.id.mapview); 


     double src_lat = SRCLAT; 
     double src_long = SRCLNG; 
     double dest_lat = DESTLAT; 
     double dest_long = DESTLNG; 
     srcGeoPoint = new GeoPoint((int) (src_lat * 1E6),(int) (src_long * 1E6)); 
     destGeoPoint = new GeoPoint((int) (dest_lat * 1E6),(int) (dest_long * 1E6)); 

     List<Overlay> mapOverlays = mapView.getOverlays(); 
     Drawable srcdrawable = this.getResources().getDrawable(R.drawable.pin_green); 
     CustomItemizedOverlay srcitemizedOverlay = new CustomItemizedOverlay(srcdrawable, this); 
     OverlayItem srcoverlayitem = new OverlayItem(srcGeoPoint, "Hello!", "This is your Location."); 

     Drawable destdrawable = this.getResources().getDrawable(R.drawable.pin_red); 
     CustomItemizedOverlay destitemizedOverlay = new CustomItemizedOverlay(destdrawable, this); 
     OverlayItem destoverlayitem = new OverlayItem(destGeoPoint, "Hello!", "This is dest Location."); 

     srcitemizedOverlay.addOverlay(srcoverlayitem); 
     destitemizedOverlay.addOverlay(destoverlayitem); 

     mapOverlays.add(srcitemizedOverlay); 
     mapOverlays.add(destitemizedOverlay); 

     connectAsyncTask _connectAsyncTask = new connectAsyncTask(); 
     _connectAsyncTask.execute();   
     mapView.setBuiltInZoomControls(true); 
     mapView.displayZoomControls(true); 
     mOverlays = mapView.getOverlays(); 
     mapView.getController().animateTo(srcGeoPoint); 
     mapView.getController().setZoom(12); 
    } 


    @Override 
    protected boolean isRouteDisplayed() { 
     // TODO Auto-generated method stub 
     return false; 
    } 

    private class connectAsyncTask extends AsyncTask<Void, Void, Void>{ 
     @Override 
     protected void onPreExecute() { 
      // TODO Auto-generated method stub 
      super.onPreExecute(); 
      SHOW YOU PROGRESS BAR HERE 
     } 
     @Override 
     protected Void doInBackground(Void... params) { 
      // TODO Auto-generated method stub 
      fetchData(); 
      return null; 
     } 
     @Override 
     protected void onPostExecute(Void result) { 
      // TODO Auto-generated method stub 
      super.onPostExecute(result);    
      if(doc!=null){ 
       Overlay ol = new MyOverLay(_activity,srcGeoPoint,srcGeoPoint,1); 
       mOverlays.add(ol); 
       NodeList _nodelist = doc.getElementsByTagName("status"); 
       Node node1 = _nodelist.item(0); 
       String _status1 = node1.getChildNodes().item(0).getNodeValue(); 
       if(_status1.equalsIgnoreCase("OK")){ 
        NodeList _nodelist_path = doc.getElementsByTagName("overview_polyline"); 
        Node node_path = _nodelist_path.item(0); 
        Element _status_path = (Element)node_path; 
        NodeList _nodelist_destination_path = _status_path.getElementsByTagName("points"); 
        Node _nodelist_dest = _nodelist_destination_path.item(0); 
        String _path = _nodelist_dest.getChildNodes().item(0).getNodeValue(); 
        List<GeoPoint> _geopoints = decodePoly(_path); 
        GeoPoint gp1; 
        GeoPoint gp2; 
        gp2 = _geopoints.get(0); 
        for(int i=1;i<_geopoints.size();i++) // the last one would be crash 
        { 

         gp1 = gp2; 
         gp2 = _geopoints.get(i); 
         Overlay ol1 = new MyOverLay(gp1,gp2,2,Color.BLUE); 
         mOverlays.add(ol1); 
        } 
        Overlay ol2 = new MyOverLay(_activity,destGeoPoint,destGeoPoint,3); 
        mOverlays.add(ol2); 

        DISMISS PROGRESS BAR HERE 

       }else{ 
        showAlert AS "Unable to find the route" 
       } 

       Overlay ol2 = new MyOverLay(_activity,destGeoPoint,destGeoPoint,3); 
       mOverlays.add(ol2); 
       DISMISS PROGRESS BAR HERE 
      }else{ 
       showAlert AS "Unable to find the route" 
      } 

     } 

    } 
    Document doc = null; 
    private void fetchData() 
    { 
     StringBuilder urlString = new StringBuilder(); 
     urlString.append("http://maps.google.com/maps/api/directions/xml?origin="); 
     urlString.append(Double.toString((double)srcGeoPoint.getLatitudeE6()/1.0E6)); 
     urlString.append(","); 
     urlString.append(Double.toString((double)srcGeoPoint.getLongitudeE6()/1.0E6)); 
     urlString.append("&destination=");//to 
     urlString.append(Double.toString((double)destGeoPoint.getLatitudeE6()/1.0E6)); 
     urlString.append(","); 
     urlString.append(Double.toString((double)destGeoPoint.getLongitudeE6()/1.0E6)); 
     urlString.append("&sensor=true&mode=driving"); 
     if(Constants.LOG)Log.d("xxx","URL="+urlString.toString());   
     HttpURLConnection urlConnection= null; 
     URL url = null; 
     try 
     { 
      url = new URL(urlString.toString()); 
      urlConnection=(HttpURLConnection)url.openConnection(); 
      urlConnection.setRequestMethod("GET"); 
      urlConnection.setDoOutput(true); 
      urlConnection.setDoInput(true); 
      urlConnection.connect(); 
      DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); 
      DocumentBuilder db = dbf.newDocumentBuilder(); 
      doc = (Document) db.parse(urlConnection.getInputStream());//Util.XMLfromString(response); 
     }catch (MalformedURLException e){ 
      e.printStackTrace(); 
     }catch (IOException e){ 
      e.printStackTrace(); 
     }catch (ParserConfigurationException e){ 
      e.printStackTrace(); 
     } 
     catch (SAXException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
    } 
    private List<GeoPoint> decodePoly(String encoded) { 

     List<GeoPoint> poly = new ArrayList<GeoPoint>(); 
     int index = 0, len = encoded.length(); 
     int lat = 0, lng = 0; 

     while (index < len) { 
      int b, shift = 0, result = 0; 
      do { 
       b = encoded.charAt(index++) - 63; 
       result |= (b & 0x1f) << shift; 
       shift += 5; 
      } while (b >= 0x20); 
      int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1)); 
      lat += dlat; 

      shift = 0; 
      result = 0; 
      do { 
       b = encoded.charAt(index++) - 63; 
       result |= (b & 0x1f) << shift; 
       shift += 5; 
      } while (b >= 0x20); 
      int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1)); 
      lng += dlng; 

      GeoPoint p = new GeoPoint((int) (((double) lat/1E5) * 1E6), 
        (int) (((double) lng/1E5) * 1E6)); 
      poly.add(p); 
     } 

     return poly; 
    } 
} 

CustomItemizedOverlay.java

import java.util.ArrayList; 

import android.content.Context; 
import android.graphics.drawable.Drawable; 

import com.google.android.maps.ItemizedOverlay; 
import com.google.android.maps.OverlayItem; 

public class CustomItemizedOverlay extends ItemizedOverlay<OverlayItem> { 

    private final ArrayList<OverlayItem> mapOverlays = new ArrayList<OverlayItem>(); 

    private Context context; 

    public CustomItemizedOverlay(Drawable defaultMarker) { 
     super(boundCenterBottom(defaultMarker)); 
    } 

    public CustomItemizedOverlay(Drawable defaultMarker, Context context) { 
     this(defaultMarker); 
     this.context = context; 
    } 

    @Override 
    protected OverlayItem createItem(int i) { 
     return mapOverlays.get(i); 
    } 

    @Override 
    public int size() { 
     return mapOverlays.size(); 
    } 

    public void addOverlay(OverlayItem overlay) { 
     mapOverlays.add(overlay); 
     this.populate(); 
    } 

} 

MyOverLay.java

import android.content.Context; 
import android.graphics.Bitmap; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.graphics.Point; 
import android.graphics.RectF; 
import android.graphics.drawable.BitmapDrawable; 
import android.graphics.drawable.Drawable; 

import com.google.android.maps.GeoPoint; 
import com.google.android.maps.MapView; 
import com.google.android.maps.Overlay; 
import com.google.android.maps.Projection; 

public class MyOverLay extends Overlay 
{ 
    private GeoPoint gp1; 
    private GeoPoint gp2; 
    //private int mRadius=6; 
    private int mode=0; 
    private int defaultColor; 
    private String text=""; 
    private Bitmap img = null; 
    Context mContext; 

    public MyOverLay(Context context,GeoPoint gp1,GeoPoint gp2,int mode) // GeoPoint is a int. (6E) 
    { 
     this.gp1 = gp1; 
     this.gp2 = gp2; 
     this.mode = mode; 
     this.mContext = context; 
     defaultColor = 999; // no defaultColor 

    } 

    public MyOverLay(GeoPoint gp1,GeoPoint gp2,int mode, int defaultColor) 
    { 
     this.gp1 = gp1; 
     this.gp2 = gp2; 
     this.mode = mode; 
     this.defaultColor = defaultColor; 
    } 
    public void setText(String t) 
    { 
     this.text = t; 
    } 
    public void setBitmap(Bitmap bitmap) 
    { 
     this.img = bitmap; 
    } 
    public int getMode() 
    { 
     return mode; 
    } 

    @Override 
    public boolean draw 
    (Canvas canvas, MapView mapView, boolean shadow, long when) 
    { 
     Projection projection = mapView.getProjection(); 
     if (shadow == false) 
     { 
      Paint paint = new Paint(); 
      paint.setAntiAlias(true); 
      Point point = new Point(); 
      projection.toPixels(gp1, point); 
      // mode=1：start 
      if(mode==1) 
      { 
       if(defaultColor==999) 
        paint.setColor(Color.BLUE); 
       else 
        paint.setColor(defaultColor);     
       // start point 
      } 
      // mode=2：path 
      else if(mode==2) 
      { 
       if(defaultColor==999) 
        paint.setColor(Color.RED); 
       else 
        paint.setColor(defaultColor); 
       Point point2 = new Point(); 
       projection.toPixels(gp2, point2); 
       paint.setStrokeWidth(5); 
       paint.setAlpha(120); 
       canvas.drawLine(point.x, point.y, point2.x,point2.y, paint); 

      } 
      /* mode=3：end */ 
      else if(mode==3) 
      { 
       /* the last path */ 

       if(defaultColor==999) 
        paint.setColor(Color.GREEN); 
       else 
        paint.setColor(defaultColor); 
       Point point2 = new Point(); 
       projection.toPixels(gp2, point2); 
       paint.setStrokeWidth(5); 
       paint.setAlpha(120); 
       canvas.drawLine(point.x, point.y, point2.x,point2.y, paint); 
       /* end point */ 

      } 
     } 
     return super.draw(canvas, mapView, shadow, when); 
    } 

}