Question

我有一个异步任务，我试图将地图标记添加到Android中的谷歌地图。我设置了我的地图并使用以下方法调用异步任务：

public class BreweryMap extends ActionbarMenu {

    BeerData e;
    String beerID;
    GoogleMap map;

    //get beer details from bundle
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_brewerymap);


        //get beer data
        Intent intent = getIntent();
        Bundle extras = intent.getExtras();
        String breweryID = extras.getString("breweryID");

        map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map))
                .getMap();



        //todo: get brewery latt and long and add marker
        //construct url
        String url = "http://api.brewerydb.com/v2/brewery/"+ breweryID +"?key=myKeyformat=json&withLocations=y";

        Log.d("map", url);
        //async task to get beer taste tag percents
        new AddBreweryMapMarkerJSON(this,map).execute(url);

当调用asycn任务时，我解析了返回的json，并解析并尝试将标记添加到我的地图中。我从json中检索了一个long和latt值，我从日志中知道。标记只是没有放在地图上。

public class AddBreweryMapMarkerJSON extends AsyncTask<String, Void, String> {

    Context c;
    private ProgressDialog Dialog;
    GoogleMap mapIn;

    public AddBreweryMapMarkerJSON(Context context, GoogleMap map)
    {
        c = context;
        mapIn = map;
        Dialog = new ProgressDialog(c);
    }

    @Override
    protected String doInBackground(String... arg0) {
        // TODO Auto-generated method stub
        return readJSONFeed(arg0[0]);
    }

    protected void onPreExecute() {
        Dialog.setMessage("Getting brewery information");

        Dialog.setTitle("Loading");
        Dialog.setCancelable(false);
        Dialog.show();
    }

    @Override
    protected void onPostExecute(String result){

        try{

            Log.d("map", "in try");
            JSONObject o = new JSONObject(result);

            Log.d("brewery", result);


            String longitude = getLong(o);
            String latt = getLatt(o);



            double longDouble = Double.parseDouble(longitude);
            double lattDouble = Double.parseDouble(latt);

            //add marker
            mapIn.addMarker(new MarkerOptions()
                    .position(new LatLng(longDouble, lattDouble))
                    .title("Hello world"));



        }
        catch(Exception e){

        }

        Dialog.dismiss();

    }

    public String getName(JSONObject json){
        String holder;



        try{
            holder = json.getJSONObject("data").getString("name");

        } catch (JSONException e) {
            holder = "N/A";
        }



        return holder;

    }



    public String getIcon(JSONObject json){
        String holder;



        try{
            holder = json.getJSONObject("data").getJSONObject("images").getString("large");

        } catch (JSONException e) {
            holder = "N/A";
        }



        return holder;

    }

    public String getDescription(JSONObject json){
        String holder;



        try{
            holder = json.getJSONObject("data").getString("description");

        } catch (JSONException e) {
            holder = "N/A";
        }



        return holder;

    }


    public String getYear(JSONObject json){
        String holder;



        try{
            holder = json.getJSONObject("data").getString("established");

        } catch (JSONException e) {
            holder = "N/A";
        }



        return holder;

    }

    public String getLatt(JSONObject json){
        String holder;



        try{
            holder = json.getJSONObject("data").getJSONArray("locations").getJSONObject(0).getString("latitude");

        } catch (JSONException e) {
            holder = "null";
        }



        return holder;

    }

    public String getLong(JSONObject json){
        String holder;



        try{
            holder = json.getJSONObject("data").getJSONArray("locations").getJSONObject(0).getString("longitude");

        } catch (JSONException e) {
            holder = "null";
        }



        return holder;

    }

    public String readJSONFeed(String URL) {
        StringBuilder stringBuilder = new StringBuilder();
        HttpClient httpClient = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet(URL);
        try {
            HttpResponse response = httpClient.execute(httpGet);
            StatusLine statusLine = response.getStatusLine();
            int statusCode = statusLine.getStatusCode();
            if (statusCode == 200) {
                HttpEntity entity = response.getEntity();
                InputStream inputStream = entity.getContent();
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(inputStream));
                String line;
                while ((line = reader.readLine()) != null) {
                    stringBuilder.append(line);
                }
                inputStream.close();
            } else {
                Log.d("JSON", "Failed to download file");
            }
        } catch (Exception e) {
            Log.d("readJSONFeed", e.getLocalizedMessage());
        }
        return stringBuilder.toString();
    }

}

Answer 1

尝试将处理映射的代码放在处理程序中，然后从AsyncTask向处理程序发送消息。通常，必须在主线程中进行接口修改，而AsyncTask显然在侧线程中运行。

Answer 2

请尝试将Google地图的相机位置设置为特定位置（如

）

CameraPosition cameraPosition = new CameraPosition.Builder（）。target（latLng） .zoom（12）//设置缩放 .tilt（30）//将相机的倾斜度设置为30度。建立（）; //从构建器创建CameraPosition // .bearing（90）//将摄像机的方向设置为向东 gMap.animateCamera（CameraUpdateFactory.newCameraPosition（cameraPosition））;

Answer 3

从你的JSON字符串中获取Lat / Lng点然后从你的JSON数组创建一个'LatLng点列表

ArrayList<LatLng> points = new ArrayList<LatLng>();

循环遍历字符串并添加到列表

points.add(new LatLng(lat,lng));

返回doInBackground

中的列表

return points;

然后在onPostExecute循环列表中并绘制每个

public void onPostExecute(ArrayList points){
    for(LatLng point : points){
        //plot the point to the map
    }
}

当然，您在申报课程时也必须更改退货类型

AsyncTask<String, Void, ArrayList<LatLng>>

Answer 4

这里的问题似乎是它不喜欢在添加标记的内部创建LatLng。通过改变这个：

//add marker
            mapIn.addMarker(new MarkerOptions()
                    .position(new LatLng(longDouble, lattDouble))
                    .title("Hello world"));

，修复了未添加的标记：

double longDouble = Double.parseDouble(longitude);
            double lattDouble = Double.parseDouble(latt);

            LatLng positionOne = new LatLng(lattDouble, longDouble);

            //add marker
            mapIn.addMarker(new MarkerOptions()
                    .position(positionOne)
                    .title(name));

使用异步任务将标记添加到Android谷歌地图

4 个答案: