使用 Google Maps Android API v2 在两点之间绘制路径 [英] Draw path between two points using Google Maps Android API v2
问题描述
Google 更改了其 Android 地图 API 并引入了 API V2.之前绘制路径的代码不适用于 API V2.
Google changed its map API for Android and introduced API V2. The previous codes for drawing path are not working with API V2.
我已经设法用 API V2 绘制了一条路径.我已经搜索了很多解决方案，但没有找到任何答案.所以我正在分享它的答案.
I have managed to draw a path with API V2. I had searched a lot for the solution but did not find any answer. So I am sharing its answer.
推荐答案
首先，我们将获得源点和目标点，我们必须在它们之间绘制路线.然后我们将这些属性传递给下面的函数.
First of all we will get source and destination points between which we have to draw route. Then we will pass these attribute to below function.
public String makeURL (double sourcelat, double sourcelog, double destlat, double destlog ){
StringBuilder urlString = new StringBuilder();
urlString.append("http://maps.googleapis.com/maps/api/directions/json");
urlString.append("?origin=");// from
urlString.append(Double.toString(sourcelat));
urlString.append(",");
urlString.append(Double.toString( sourcelog));
urlString.append("&destination=");// to
urlString.append(Double.toString( destlat));
urlString.append(",");
urlString.append(Double.toString( destlog));
urlString.append("&sensor=false&mode=driving&alternatives=true");
urlString.append("&key=YOUR_API_KEY");
return urlString.toString();
}
此函数将生成我们将发送以获取方向 API 响应的 url.然后我们将解析该响应.解析器类是
This function will make the url that we will send to get Direction API response. Then we will parse that response . The parser class is
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public String getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "
");
}
json = sb.toString();
is.close();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
return json;
}
}
这个解析器将返回我们字符串.我们会这样称呼它.
This parser will return us string. We will call it like that.
JSONParser jParser = new JSONParser();
String json = jParser.getJSONFromUrl(url);
现在我们将此字符串发送到我们的 drawpath 函数.绘制路径函数是
Now we will send this string to our drawpath function. The drawpath function is
public void drawPath(String result) {
try {
//Tranform the string into a json object
final JSONObject json = new JSONObject(result);
JSONArray routeArray = json.getJSONArray("routes");
JSONObject routes = routeArray.getJSONObject(0);
JSONObject overviewPolylines = routes.getJSONObject("overview_polyline");
String encodedString = overviewPolylines.getString("points");
List<LatLng> list = decodePoly(encodedString);
Polyline line = mMap.addPolyline(new PolylineOptions()
.addAll(list)
.width(12)
.color(Color.parseColor("#05b1fb"))//Google maps blue color
.geodesic(true)
);
/*
for(int z = 0; z<list.size()-1;z++){
LatLng src= list.get(z);
LatLng dest= list.get(z+1);
Polyline line = mMap.addPolyline(new PolylineOptions()
.add(new LatLng(src.latitude, src.longitude), new LatLng(dest.latitude, dest.longitude))
.width(2)
.color(Color.BLUE).geodesic(true));
}
*/
}
catch (JSONException e) {
}
}
以上代码将在mMap上绘制路径.decodePoly 的代码是
Above code will draw the path on mMap. The code of decodePoly is
private List<LatLng> decodePoly(String encoded) {
List<LatLng> poly = new ArrayList<LatLng>();
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;
LatLng p = new LatLng( (((double) lat / 1E5)),
(((double) lng / 1E5) ));
poly.add(p);
}
return poly;
}
由于方向调用可能需要时间，所以我们将在异步任务中完成所有这些.我的异步任务是
As direction call may take time so we will do all this in Asynchronous task. My Asynchronous task was
private class connectAsyncTask extends AsyncTask<Void, Void, String>{
private ProgressDialog progressDialog;
String url;
connectAsyncTask(String urlPass){
url = urlPass;
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
progressDialog = new ProgressDialog(MainActivity.this);
progressDialog.setMessage("Fetching route, Please wait...");
progressDialog.setIndeterminate(true);
progressDialog.show();
}
@Override
protected String doInBackground(Void... params) {
JSONParser jParser = new JSONParser();
String json = jParser.getJSONFromUrl(url);
return json;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
progressDialog.hide();
if(result!=null){
drawPath(result);
}
}
}
我希望它会有所帮助.
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