android - 在Google Maps Android中显示路线

Question

我在安卓系统中遇到了谷歌地图问题。
我成功地在安卓上显示了地图。但当我想显示路线方向时，它会出错。
奇怪的是。我的代码一周前运行得很好。但当我今天运行它时，它出现了错误。所以我试图找到新的代码，但失败了。这是我的密码。
这是我的公路课

public class Road {
    public String mName;
    public String mDescription;
    public int mColor;
    public int mWidth;
    public double[][] mRoute = new double[][] {};
    public Point[] mPoints = new Point[] {};}

这是我的重点课

public class Point {
    String mName;
    String mDescription;
    String mIconUrl;
    double mLatitude;
    double mLongitude;}

这是我的MapOverlay类

public class MapOverlay extends com.google.android.maps.Overlay {   
 Road mRoad;
 ArrayList<GeoPoint> mPoints;

 public MapOverlay(Road road, MapView mv) {
         mRoad = road;
         if (road.mRoute.length > 0) {
                 mPoints = new ArrayList<GeoPoint>();
                 for (int i = 0; i < road.mRoute.length; i++) {
                         mPoints.add(new GeoPoint((int) (road.mRoute[i][1] * 1000000),
                                         (int) (road.mRoute[i][0] * 1000000)));
                 }
                 int moveToLat = (mPoints.get(0).getLatitudeE6() + (mPoints.get(
                                 mPoints.size() - 1).getLatitudeE6() - mPoints.get(0)
                                 .getLatitudeE6()) / 2);
                 int moveToLong = (mPoints.get(0).getLongitudeE6() + (mPoints.get(
                                 mPoints.size() - 1).getLongitudeE6() - mPoints.get(0)
                                 .getLongitudeE6()) / 2);
                 GeoPoint moveTo = new GeoPoint(moveToLat, moveToLong);

                 MapController mapController = mv.getController();
                 mapController.animateTo(moveTo);
                 mapController.setZoom(7);
         }
 }

 @Override
 public boolean draw(Canvas canvas, MapView mv, boolean shadow, long when) {
         super.draw(canvas, mv, shadow);
         drawPath(mv, canvas);
         return true;
 }

 public void drawPath(MapView mv, Canvas canvas) {
         int x1 = -1, y1 = -1, x2 = -1, y2 = -1;
         Paint paint = new Paint();
         paint.setColor(Color.GREEN);
         paint.setStyle(Paint.Style.STROKE);
         paint.setStrokeWidth(3);
         for (int i = 0; i < mPoints.size(); i++) {
                 Point point = new Point();
                 mv.getProjection().toPixels(mPoints.get(i), point);
                 x2 = point.x;
                 y2 = point.y;
                 if (i > 0) {
                         canvas.drawLine(x1, y1, x2, y2, paint);
                 }
                 x1 = x2;
                 y1 = y2;
         }
 }}

这是我的道路提供商课程

public class RoadProvider {

    public static Road getRoute(InputStream is) {
            KMLHandler handler = new KMLHandler();
            try {
                    SAXParser parser = SAXParserFactory.newInstance().newSAXParser();
                    parser.parse(is, handler);
            } catch (ParserConfigurationException e) {
                    e.printStackTrace();
            } catch (SAXException e) {
                    e.printStackTrace();
            } catch (IOException e) {
                    e.printStackTrace();
            }
            return handler.mRoad;
    }

    public static String getUrl(double fromLat, double fromLon, double toLat,
                    double toLon) {// connect to map web service
            StringBuffer urlString = new StringBuffer();
            urlString.append("http://maps.google.com/maps?f=d&hl=en");
            urlString.append("&saddr=");// from
            urlString.append(Double.toString(fromLat));
            urlString.append(",");
            urlString.append(Double.toString(fromLon));
            urlString.append("&daddr=");// to
            urlString.append(Double.toString(toLat));
            urlString.append(",");
            urlString.append(Double.toString(toLon));
            urlString.append("&ie=UTF8&0&om=0&output=kml");
            return urlString.toString();
    }}
class KMLHandler extends DefaultHandler {
    Road mRoad;
    boolean isPlacemark;
    boolean isRoute;
    boolean isItemIcon;
    private Stack mCurrentElement = new Stack();
    private String mString;

    public KMLHandler() {
            mRoad = new Road();
    }

    public void startElement(String uri, String localName, String name,
                    Attributes attributes) throws SAXException {
            mCurrentElement.push(localName);
            if (localName.equalsIgnoreCase("Placemark")) {
                    isPlacemark = true;
                    mRoad.mPoints = addPoint(mRoad.mPoints);
            } else if (localName.equalsIgnoreCase("ItemIcon")) {
                    if (isPlacemark)
                            isItemIcon = true;
            }
            mString = new String();
    }

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

    public void endElement(String uri, String localName, String name)
                    throws SAXException {
            if (mString.length() > 0) {
                    if (localName.equalsIgnoreCase("name")) {
                            if (isPlacemark) {
                                    isRoute = mString.equalsIgnoreCase("Route");
                                    if (!isRoute) {
                                            mRoad.mPoints[mRoad.mPoints.length - 1].mName = mString;
                                    }
                            } else {
                                    mRoad.mName = mString;
                            }
                    } else if (localName.equalsIgnoreCase("color") && !isPlacemark) {
                            mRoad.mColor = Integer.parseInt(mString, 16);
                    } else if (localName.equalsIgnoreCase("width") && !isPlacemark) {
                            mRoad.mWidth = Integer.parseInt(mString);
                    } else if (localName.equalsIgnoreCase("description")) {
                            if (isPlacemark) {
                                    String description = cleanup(mString);
                                    if (!isRoute)
                                            mRoad.mPoints[mRoad.mPoints.length - 1].mDescription = description;
                                    else
                                            mRoad.mDescription = description;
                            }
                    } else if (localName.equalsIgnoreCase("href")) {
                            if (isItemIcon) {
                                    mRoad.mPoints[mRoad.mPoints.length - 1].mIconUrl = mString;
                            }
                    } else if (localName.equalsIgnoreCase("coordinates")) {
                            if (isPlacemark) {
                                    if (!isRoute) {
                                            String[] xyParsed = split(mString, ",");
                                            double lon = Double.parseDouble(xyParsed[0]);
                                            double lat = Double.parseDouble(xyParsed[1]);
                                            mRoad.mPoints[mRoad.mPoints.length - 1].mLatitude = lat;
                                            mRoad.mPoints[mRoad.mPoints.length - 1].mLongitude = lon;
                                    } else {
                                            String[] coodrinatesParsed = split(mString, " ");
                                            int lenNew = coodrinatesParsed.length;
                                            int lenOld = mRoad.mRoute.length;
                                            double[][] temp = new double[lenOld + lenNew][2];
                                            for (int i = 0; i < lenOld; i++) {
                                                    temp[i] = mRoad.mRoute[i];
                                            }
                                            for (int i = 0; i < lenNew; i++) {
                                                    String[] xyParsed = split(coodrinatesParsed[i], ",");
                                                    for (int j = 0; j < 2 && j < xyParsed.length; j++)
                                                            temp[lenOld + i][j] = Double
                                                                            .parseDouble(xyParsed[j]);
                                            }
                                            mRoad.mRoute = temp;
                                    }
                            }
                    }
            }
            mCurrentElement.pop();
            if (localName.equalsIgnoreCase("Placemark")) {
                    isPlacemark = false;
                    if (isRoute)
                            isRoute = false;
            } else if (localName.equalsIgnoreCase("ItemIcon")) {
                    if (isItemIcon)
                            isItemIcon = false;
            }
    }

    private String cleanup(String value) {
            String remove = "<br/>";
            int index = value.indexOf(remove);
            if (index != -1)
                    value = value.substring(0, index);
            remove = "&#160;";
            index = value.indexOf(remove);
            int len = remove.length();
            while (index != -1) {
                    value = value.substring(0, index).concat(
                                    value.substring(index + len, value.length()));
                    index = value.indexOf(remove);
            }
            return value;
    }

    public Point[] addPoint(Point[] points) {
            Point[] result = new Point[points.length + 1];
            for (int i = 0; i < points.length; i++)
                    result[i] = points[i];
            result[points.length] = new Point();
            return result;
    }

    private static String[] split(String strString, String strDelimiter) {
            String[] strArray;
            int iOccurrences = 0;
            int iIndexOfInnerString = 0;
            int iIndexOfDelimiter = 0;
            int iCounter = 0;
            if (strString == null) {
                    throw new IllegalArgumentException("Input string cannot be null.");
            }
            if (strDelimiter.length() <= 0 || strDelimiter == null) {
                    throw new IllegalArgumentException(
                                    "Delimeter cannot be null or empty.");
            }
            if (strString.startsWith(strDelimiter)) {
                    strString = strString.substring(strDelimiter.length());
            }
            if (!strString.endsWith(strDelimiter)) {
                    strString += strDelimiter;
            }
            while ((iIndexOfDelimiter = strString.indexOf(strDelimiter,
                            iIndexOfInnerString)) != -1) {
                    iOccurrences += 1;
                    iIndexOfInnerString = iIndexOfDelimiter + strDelimiter.length();
            }
            strArray = new String[iOccurrences];
            iIndexOfInnerString = 0;
            iIndexOfDelimiter = 0;
            while ((iIndexOfDelimiter = strString.indexOf(strDelimiter,
                            iIndexOfInnerString)) != -1) {
                    strArray[iCounter] = strString.substring(iIndexOfInnerString,
                                    iIndexOfDelimiter);
                    iIndexOfInnerString = iIndexOfDelimiter + strDelimiter.length();
                    iCounter += 1;
            }

            return strArray;
    }}

这是主要活动

public class GoogleMap233Activity extends MapActivity {
     LinearLayout linearLayout;
     MapView mapView;
     private Road mRoad;    
     @Override
     public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      mapView = (MapView) findViewById(R.id.mapview);
      mapView.setBuiltInZoomControls(true);    
      new Thread() {
       @Override
       public void run() {
        double fromLat = 49.85, fromLon = 24.016667; 
        double toLat = 50.45, toLon = 30.523333;
        String url = RoadProvider
          .getUrl(fromLat, fromLon, toLat, toLon);
        InputStream is = getConnection(url);

        mRoad = RoadProvider.getRoute(is);
        Log.i("Road", mRoad.mRoute.length+"");
        mHandler.sendEmptyMessage(0);
       }
      }.start();
     }

     Handler mHandler = new Handler() {
      public void handleMessage(android.os.Message msg) {
       TextView textView = (TextView) findViewById(R.id.description);
       textView.setText(mRoad.mName + " " + mRoad.mDescription);
       MapOverlay mapOverlay = new MapOverlay(mRoad, mapView);
       List<Overlay> listOfOverlays = mapView.getOverlays();
       listOfOverlays.clear();
       listOfOverlays.add(mapOverlay);
       mapView.invalidate();
      };
     };

     private InputStream getConnection(String url) {
      InputStream is = null;
      try {
       URLConnection conn = new URL(url).openConnection();
       is = conn.getInputStream();
      } catch (MalformedURLException e) {
       e.printStackTrace();
      } catch (IOException e) {
       e.printStackTrace();
      }
      return is;
     }    
     @Override
     protected boolean isRouteDisplayed() {
      return false;
     }
    }

此代码在mpoints.size（）中的drawPath（）方法中的mapOverlay（）类中显示错误。这是因为mpoints为空。基于mapOverlay（）的构造函数，mpoints为空，因为road.mroute.length==0。当我查看Roadprovider的日志时，上面写着

SAXParser parser = SAXParserFactory.newInstance().newSAXParser();
                parser.parse(is, handler);

有人能帮我查一下吗？非常感谢。

Answer 1

我想出来了。这个链接对我有很大帮助。
Google Maps API Version difference
希望这对你有帮助。