我的应用程序可以使用 JSON 提供路径/方向。如何在 JSON 给出的路径中更改不同的颜色？
例如，从 A 点到 B 点为红色，B 到 C 为黄色，C 到 D 为绿色，以此类推。
代码是：
在 JSON 中获取积分。
private void parsing(GeoPoint start, GeoPoint end) throws ClientProtocolException, IOException, JSONException, URISyntaxException{
HttpClient httpclient = new DefaultHttpClient();
StringBuilder urlstring = new StringBuilder();
urlstring.append("https://maps.googleapis.com/maps/api/directions/json?origin=")
.append(Double.toString((double)start.getLatitudeE6()/1E6)).append(",").append(Double.toString((double)start.getLongitudeE6()/1E6)).append("&destination=")
.append(Double.toString((double)end.getLatitudeE6()/1E6)).append(",").append(Double.toString((double)end.getLongitudeE6()/1E6))
.append("&sensor=false");
//urlstring.append("http://maps.googleapis.com/maps/api/directions/json?origin=Toronto&destination=Montreal&sensor=true");
url = new URI(urlstring.toString());
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
InputStream is = null;
is = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
sb.append(reader.readLine() + "\n");
String line = "0";
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
reader.close();
String result = sb.toString();
JSONObject jsonObject = new JSONObject(result);
JSONArray routeArray = jsonObject.getJSONArray("routes");
JSONObject routes = routeArray.getJSONObject(0);
JSONObject overviewPolylines = routes.getJSONObject("overview_polyline");
String encodedString = overviewPolylines.getString("points");
List<GeoPoint> pointToDraw = decodePoly(encodedString);
//Added line:
mv_mapview.getOverlays().add(new RoutePathOverlay(pointToDraw));
}
JSON 给出的地理点列表。
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));
//n = new Node(p,);
poly.add(p);
}
return poly;
}
和覆盖类
public class RoutePathOverlay extends Overlay {
private int _pathColor;
private final List<GeoPoint> _points;
private boolean _drawStartEnd;
public RoutePathOverlay(List<GeoPoint> points) {
this(points, Color.GREEN, true);
}
public RoutePathOverlay(List<GeoPoint> points, int pathColor, boolean drawStartEnd) {
_points = points;
_pathColor = pathColor;
_drawStartEnd = drawStartEnd;
}
private void drawOval(Canvas canvas, Paint paint, Point point) {
Paint ovalPaint = new Paint(paint);
ovalPaint.setStyle(Paint.Style.FILL_AND_STROKE);
ovalPaint.setStrokeWidth(2);
int _radius = 6;
RectF oval = new RectF(point.x - _radius, point.y - _radius, point.x + _radius, point.y + _radius);
canvas.drawOval(oval, ovalPaint);
}
public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when) {
Projection projection = mapView.getProjection();
if (shadow == false && _points != null) {
Point startPoint = null, endPoint = null;
Path path = new Path();
//We are creating the path
for (int i = 0; i < _points.size(); i++) {
GeoPoint gPointA = _points.get(i);
Point pointA = new Point();
projection.toPixels(gPointA, pointA);
//if()
if (i == 0) { //This is the start point
startPoint = pointA;
path.moveTo(pointA.x, pointA.y);
} else {
if (i == _points.size() - 1)//This is the end point
endPoint = pointA;
path.lineTo(pointA.x, pointA.y);
}
}
Paint paint = new Paint();
paint.setAntiAlias(true);
// if(){
paint.setColor(_pathColor);
//}
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(5);
paint.setAlpha(90);
if (getDrawStartEnd()) {
if (startPoint != null) {
drawOval(canvas, paint, startPoint);
}
if (endPoint != null) {
drawOval(canvas, paint, endPoint);
}
}
if (!path.isEmpty())
canvas.drawPath(path, paint);
}
return super.draw(canvas, mapView, shadow, when);
}
public boolean getDrawStartEnd() {
return _drawStartEnd;
}
public void setDrawStartEnd(boolean markStartEnd) {
_drawStartEnd = markStartEnd;
}
}