android.os.NetworkOnMainThreadException，同时从 JSON 解析数据

Question

嗨，朋友们，我正在开发一个应用程序，它需要：

• 将所有国家/地区名称放入列表中。
• 国家/地区列表来自 JSON。

我的网络服务是：

https://maps.googleapis.com/maps/api/geocode/json

在从经度和纬度转换国家名称时出现以下错误。

错误是：

Maps Call URL::android.os.NetworkOnMainThreadException
TMP ALBUM CountryAll::Anguilla
Error in Parsig JSON:org.json.JSONException: Index 4 out of range [0..1)
Error in Post Execute:java.lang.NullPointerException

我的 JSON 代码是：

 public class GetLatLngAsyncTask extends AsyncTask<ArrayList<String>, Void, String>
    {
        JSONObject jObject;
        JSONObject places = null;
        String lat;
        ProgressDialog progressDialog;
        protected void onPreExecute() 
        {
            super.onPreExecute();            
            progressDialog = new ProgressDialog(Map_View.this);
            progressDialog.setTitle("Getting Users Location");
            progressDialog.setMessage("Please wait");
            progressDialog.setCancelable(false);
            progressDialog.setIndeterminate(true);
            progressDialog.show();
        }

        @Override
        protected String doInBackground(ArrayList<String>... params) 
        {
            try
            {
                 double lng1 = 0;
                 double lat1 = 0;
                 lng1=lat1=0;

                 StringBuilder stringBuilder = new StringBuilder();

                 JSONObject jsonObject = new JSONObject();

                 try
                 {
                     for(int i=0;i<MapListData.size();i++)
                     {
                         String countryAll=MapListData.get(i).get("country");

                         countryAll = countryAll.replaceAll(" ","%20");

                         HttpPost httppost = new HttpPost("http://maps.google.com/maps/api/geocode/json?address=" + countryAll + "&sensor=false");

                         HttpClient client = new DefaultHttpClient();

                         HttpResponse response;
                         stringBuilder = new StringBuilder();

                         response = client.execute(httppost);
                         HttpEntity entity = response.getEntity();
                         InputStream stream = entity.getContent();
                         int b;

                         while ((b = stream.read()) != -1) 
                         {
                             stringBuilder.append((char) b);
                         }

                         try 
                         {
                             jsonObject = new JSONObject(stringBuilder.toString());

                             Log.v("TMP ALBUM","TMP ALBUM CountryAll::"+countryAll);


                             lng1 = ((JSONArray)jsonObject.get("results")).getJSONObject(i)
                                         .getJSONObject("geometry").getJSONObject("location")
                                         .getDouble("lng");
                             lat1 = ((JSONArray)jsonObject.get("results")).getJSONObject(i)
                                         .getJSONObject("geometry").getJSONObject("location")
                                         .getDouble("lat");

                             Log.v("Langitude is:",""+lng1);
                             Log.v("Latitude is:",""+lat1);

                             tmp_album1 = new HashMap<String, String>();
                             tmp_album1.put("Lng",""+lng1);
                             tmp_album1.put("lat",""+lat1);
                             MapListData1.add(tmp_album1);

                             Log.v("MAP LIST","MAP LIST1::"+MapListData1);


                         }
                         catch (JSONException e) 
                         {
                             Log.v("Error","Error in Parsig JSON:"+e);
                         }
                     }
                 }
                 catch (Exception e) 
                 {
                     Log.v("Error In MAPS","Maps Call URL::"+e);
                 } 
            }   
            catch(Exception e)
            {
                Log.v("Error In MAPS","Maps ASYC::"+e);
            }
            return lat;
        }

        @Override
        protected void onPostExecute(String result) 
        {
            // TODO Auto-generated method stub
            super.onPostExecute(result);
            try
            {
                for(int i=0;i<MapListData1.size();i++)
                {
                    double Lang=Double.valueOf(MapListData1.get(i).get("lng"));
                    double Lat=Double.valueOf(MapListData1.get(i).get("lat"));

                    MarkerOptions marker = new MarkerOptions()
                        .position(new LatLng(Lang,Lat))
                        .title("Your Friend Is in "+country);

                    marker.icon(BitmapDescriptorFactory
                            .defaultMarker(BitmapDescriptorFactory.HUE_RED));

                    googleMap.addMarker(marker);
                    Log.v("Marker","marker Added");

                    CameraPosition cameraPosition = new CameraPosition.Builder()
                        .target(new LatLng(Lang,Lat))
                        .zoom(2).build();
                    googleMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
                }
            }
            catch(Exception e)
            {
                Log.v("ERROR","Error in Post Execute:"+e);
            }
            progressDialog.dismiss();
        }

请帮助我。告诉我哪里出错了。

非常感谢。

Answer 1

启用严格模式以消除此异常。只需将此代码放在您的活动的 super.onCreate() 之后，如下所示：-

super.onCreate(savedInstanceState);
**StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);** 
setContentView(R.layout.main);