正在下載折線信息

Question

我在嘗試下載並顯示折線。

我有這樣的任務異步設置：

private class taskGetPolyline extends AsyncTask<Void, Void, Void> { 

    ProgressDialog dialog; 
    StringBuilder urlString; 
    String response; 
    int i; 

    private taskGetPolyline(int i) { 
     this.i = i; //passes in id of closest marker 
    } 

    @Override protected void onPreExecute() { 
     super.onPreExecute(); 

     dialog = new ProgressDialog(ContentActivity.this); 
     dialog.setTitle(getResources().getText(
       R.string.progress_download_route)); 
     dialog.setMessage(getResources().getText(
       R.string.progress_please_wait)); dialog.setCancelable(false); 
       dialog.setCanceledOnTouchOutside(false); dialog.show(); 

     urlString = new StringBuilder(); urlString 
       .append("http://maps.googleapis.com/maps/api/directions/json"); 
     urlString.append("?origin="); 
     urlString.append(LOCATION_CURRENT.getLatitude()); urlString.append(","); 
     urlString.append(LOCATION_CURRENT.getLongitude()); 
     urlString.append("&destination="); 

     urlString.append(arrayLocation[i].latitude); 
     urlString.append(","); 
     urlString.append(arrayLocation[i].longitude); 
     urlString.append("&sensor=false"); 

     Log.i("DEBUG","link: " + urlString.toString()); 

    } 

    @Override 
    protected Void doInBackground(Void... params) { 

     try { 
      HttpClient Client = new DefaultHttpClient(); 
      HttpGet httpGet = new HttpGet(urlString.toString()); 
      ResponseHandler<String> responseHandler = new BasicResponseHandler(); 
      response = Client.execute(httpGet, responseHandler); 

      Log.i("DEBUG", "response = " + response); 
     } catch (Exception e) { 
      Log.i("Exception", e.getMessage()); 
     } 

     return null; 
    } 

    @Override 
    protected void onPostExecute(Void result) { 

     JSONObject jsonResponse; 
     try { 
      jsonResponse = new JSONObject(response); 
      JSONObject jsonOverviewPolylines = jsonResponse 
        .getJSONObject("overview_polyline"); 

      PolylineOptions polylineOptions = new PolylineOptions() 
        .addAll(decodePolyLine(jsonOverviewPolylines.toString())); 
      currentPolyline = map.addPolyline(polylineOptions); 



     } catch (JSONException e) { 

      e.printStackTrace(); 
     } 
     dialog.dismiss(); 
    } 

} 

但是當我運行這段代碼我得到logcat的警告：

10-31 14:48:43.744: W/System.err(10724): org.json.JSONException: No value for overview_polyline 

日誌裏顯示整個鏈接，這很好。這裏的例子：不顯示，直到在日誌中結束 http://maps.googleapis.com/maps/api/directions/json?origin=46.14928015,16.00907806&destination=45.831534,16.02944&sensor=false

響應：

10-31 14:55:35.744: I/DEBUG(11671): response = { 
10-31 14:55:35.744: I/DEBUG(11671): "routes" : [ 
10-31 14:55:35.744: I/DEBUG(11671):  { 
10-31 14:55:35.744: I/DEBUG(11671):   "bounds" : { 
10-31 14:55:35.744: I/DEBUG(11671):    "northeast" : { 
10-31 14:55:35.744: I/DEBUG(11671):    "lat" : 46.1724292, 
10-31 14:55:35.744: I/DEBUG(11671):    "lng" : 16.0385437 
10-31 14:55:35.744: I/DEBUG(11671):    }, 
10-31 14:55:35.744: I/DEBUG(11671):    "southwest" : { 
10-31 14:55:35.744: I/DEBUG(11671):    "lat" : 45.7876853, 
10-31 14:55:35.744: I/DEBUG(11671):    "lng" : 15.8190462 
10-31 14:55:35.744: I/DEBUG(11671):    } 
10-31 14:55:35.744: I/DEBUG(11671):   }, 
... 
10-31 14:55:35.744: I/DEBUG(11671):      "html_instructions" : "Slight \u003cb\u003eright\u003c/b\u003e toward \u003cb\u003eVelika Petrovagorska\u003c/b\u003e", 
10-31 14:55:35.744: I/DEBUG(11671):      "maneuver" : "turn-slight-right", 
10-31 14:55:35.744: I/DEBUG(11671):      "polyline" : { 
10-31 14:55:35.744: I/DEBUG(11671):       "points" : "yxtxGixu`BSMQGy@QWKWQOOMKKOGMCO?QFOJUL[FQ@OB_@Bs@@k@?e@E_AI{@IiAEYEWCQCY?Y?]@m@" 
10-31 14:55:35.744: I/DEBUG(11671):      }, 
10-31 14:55:35.744: I/DEBUG(11671):      "start_location" : { 
10-31 14:55:35.744: I/DEBUG(11671):       "lat" : 46.1506939, 
10-31 14:55:35.744: I/DEBUG(11671):       "lng" : 16.0091667 
10-31 14:55:35.744: I/DEBUG(11671):      }, 
10-31 14:55:35.744: I/DEBUG(11671):      "travel_mode" : "DRIVING" 
10-31 14:55:35.744: I/DEBUG(11671):     }, 
10-31 14:55:35.744: I/DEBUG(11671):     { 
10-31 14:55:35.744: I/DEBUG(11671):      "distance" : { 
10-31 14:55:35.744: I/DEBUG(11671):       "text" : 

我失去了這部分從響應：

 "overview_polyline" : { 
     "points" : "iptxGcxu`Bu@r@wAe@uCa@mDqBj@eD_@}JGcBMu@}@_@mCc@m@B}GpBkFvBuOxDkE~AgGtDgFb@qFe@}EUkC^qA~AeAb@aBi@aC~AeFrAsDzBo@u@uCWuFfAmEfB}AtB?tAnKbPdIbOEh@a@h@}An@g@`C~@bDUrEAhAdEbCtCvBb@xA?nIv@bAzFbAdCjCrEdMt@jNmAlDoBbFO`Gf@vFrBpIXtBbBjCxEzJ|@xC|B|IjBdBjAbEjBxAxAW`BOvB|BvDhEpHlC|AnCxAhEr@v@?j@sExBcApANr@f@hAFlAzApFCpFiBv@_AzAbApEhAlC`AiB`AoAvC^nBvDxAv@jE}Cx@WnA~BfB]d@PQfCsA~Hw@fJ\\vLdCzEv@~GdBxBxBdGdAhEjA~Ab@xF\\`Bm@hAaAjAg@lGAzMtA`IlGdHzJtFlF`B|Mw@dGvExMbMnATx@c@lEmFrBFtBbAxBJ~BaApEkCjMz@lI|@hCQbF`B~IAdHzBpFlDrIhBvBrErEvj@nBb[hAfGHpGWjO@pHbBnChCtIhBdKdFdObCxBrCjDhAzFbBnAtHDlSyAlFl@`HnBzG~@bDMfDm@tC?tCGvA^rFeAlFv@|DTbCxB?NRPNWAOp@wBnD{Kl@NhBGbNuJlEc@nBlApBxDrBtFbBd@nAcCDyDfAoEpNgLfNmJbX}M~JuD~VwGtQ{Cda@oCb_@v@nQbAnK[fKkCns@e`@~NaF~MqAjNb@vLrClK~FxHjHxj@l~@rRb`@lMzZbw@rtBdSph@~In\\rFjP|GfMzHvJzIjH|GdDzzAdf@niAr^|I`EzFxCrMhJjSnSbHhIvSvTtGxG|MzLjQlLzUzK`KfD`XlFnh@nFvVjBrSbCzYdHta@pNxT|IbPfExVdDdXFfXgChTaFpr@cXzMaEp`@_HvPw@pPiBlIaCnSgF|Q_B|LHvMjAjLjCdS~Hvb@pTpZnObSpIdTnFxIxApVfBbZK~[oD|WmHjWuL|[wUhW_Xrj@cm@n_@{_@fO{JlSaIdFwCvDcDbCwB|B~@DlEw@fAoABuAwAmAiCeJ}SyJwUaJiWuFwVwC}SeBcUs@u_@Zwk@b@y}@`Bc_ApGkdB~DodAtA}_Aw@}b@c@y^b@al@Fmi@uA_t@_D_cBcByy@BwGt@U|@zCeB|Ck@`@kOfL}Y`QkPlHwBv@{I{h@sCwLkCiRoWmyA_Jey@eK_y@WqCaAPuGhBqVnFyDh@cBj@R|Ax@vFhB~M{@JkLh@oLp@}K~CuF~ByAh@NdA" 
    }, 
    "summary" : "E59", 
    "warnings" : [], 
    "waypoint_order" : [] 
    } 
    ], 
"status" : "OK" 
} 

任何人有任何想法，爲什麼我可以不會得到全部答覆，然後只解析「overview_polyline」標籤？

Answer 1

您無法從jsonResponse對象正確讀取它。您嘗試從基本Json讀取，但它實際上是從「路由」標記中的一個Jsons中讀取的。你從響應採摘第一路徑代碼將是這樣的：

JsonArray routes = jsonResponse.optJsonArray("routes"); 
if (routes != null && route.length() > 0) { 
    JsonObject firstRoute = route.optJsonObject(1); 
    if (firstRoute != null) { 
     JsonArray waypoints = firstRoute.optJsonArray("waypoint_order"); 
     JsonObject overviewPolilyne = firstRoute.optJsonObject("overview_polyline"); 
    } 
}