Question

我正在尝试下载并显示折线。

我有这个异步任务设置：

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();
    }

}

但是当我运行这段代码时，我会在logcat中收到警告：

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

日志显示整个链接，没关系。这是一个例子： http://maps.googleapis.com/maps/api/directions/json?origin=46.14928015,16.00907806&destination=45.831534,16.02944&sensor=false

响应不会显示到日志结尾：

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" :

我在回复中遗漏了这一部分：

     "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"
}

任何人都知道为什么我无法得到完整的回复，然后只解析“overview_polyline”标签？

Answer 1

您没有从jsonResponse对象中正确读取它。你试着从基础Json读取，但它实际上是在＃34;路由＆＃34;中的一个Jsons中。标签。从响应中选择第一条路线的代码如下：

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");
    }
}

下载折线信息

1 个答案: