Google Maps API v2 HeatMap无法可靠地展示

Question

好的，我正在努力实现从服务器提取的数据的热图。我将它基于官方的Google热图api，并且我的代码基于他们的代码演示。但是，我的代码不起作用。有时它会显示热图，但通常不会显示任何内容。我已经仔细检查以确保数据进入，因此缺少数据不是问题。我可以很好地在地图上玩制造商，它似乎只是热图，或者可能是叠加，不能正常工作。 mOverlay和mProvider声明为私有变量，并在下面的方法中实例化。我不知道为什么它没有出现。下面是我获取和显示热图的完整方法。

 private class sendBox extends AsyncTask<String, Void, HttpResponse> {

    @Override
    protected HttpResponse doInBackground(String... urls) {
        try {
            DefaultHttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost(urls[0]);
            for(String s : Constants.COOKIES){
                httppost.addHeader("Cookie", s);
            }

            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(4);


            //top_lat bot_lat left_long right_long
            nameValuePairs.add(new BasicNameValuePair("top_lat", Constants.TOP_LAT+""));
            nameValuePairs.add(new BasicNameValuePair("bot_lat", Constants.BOT_LAT+""));
            nameValuePairs.add(new BasicNameValuePair("left_long", Constants.LEFT_LONG+""));
            nameValuePairs.add(new BasicNameValuePair("right_long", Constants.RIGHT_LONG+""));
            //possibly change that to latlng variable on top

            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            // Execute HTTP Post Request
            httpclient = new DefaultHttpClient();
            return httpclient.execute(httppost);
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("HTTP error ");

        }
        return null;
    }
    protected void onPostExecute(HttpResponse result) {
        InputStream is = null;
        JSONObject jObj = null;
        String json = "";

        if(result !=null){ //checks if there actually is a response
            HttpEntity httpEntity = result.getEntity();

            System.out.println(result.getStatusLine().getStatusCode());
            try {
                is = httpEntity.getContent();
            }catch (Exception e) {
                Log.e("IS", "Error converting result " + e.toString());
            }
        }
        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 + "\n");
            }
            is.close(); //reads the json object as string
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        // try to parse the string to a JSON object
        try {
            jObj = new JSONObject(json); //converts string to a json object, mad errors if it isn't json object
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }
        try {
            JSONArray data =(JSONArray) jObj.get("data");
            ArrayList<WeightedLatLng> list = new ArrayList<WeightedLatLng>();
            for(int i = 0; i < data.length(); i++) {
                JSONObject temp = (JSONObject) data.get(i);
                Log.d("data", temp.get("latitude") + ","+temp.get("longitude")+" " + temp.get("weight").toString());
                WeightedLatLng lat = new WeightedLatLng(new LatLng(Double.parseDouble(temp.get("latitude").toString()),
                        Double.parseDouble(temp.get("longitude").toString())), Double.parseDouble(temp.get("weight").toString()));
                list.add(lat);
            }

            // Gradient whatnot
            int[] colors = {
                    Color.rgb(102, 0, 255), // green
                    Color.rgb(255, 0, 0)    // red
            };
            float[] startPoints = {
                    0.2f, 1f
            };
            Gradient gradient = new Gradient(colors, startPoints);
            // Create the tile provider.
            if(list.size()>0) {
                if (mProvider != null) {
                    mProvider.setWeightedData(list);
                    mOverlay.clearTileCache();
                    Log.d("Is Null", "False");
                } else {
                    mProvider = new HeatmapTileProvider.Builder()
                            .weightedData(list)
                            .gradient(gradient)
                            .build();
                    mProvider.setRadius(50);
                    mOverlay = map.addTileOverlay(new TileOverlayOptions().tileProvider(mProvider));
                    Log.d("Is Null", "True");
                }
            }
            canRefresh=true;
        } catch (Exception e) {

            e.printStackTrace();
        }
    }