Distance Matrix API AsyncTask Java

Question

我一直在尝试使用距离矩阵API来获取两个位置之间的步行时间和距离。我想将此结果（距离和持续时间）存储在可以从其他类/活动访问的变量中。

我设法使用AsyncTask获得时间和持续时间，但是当我尝试将它们存储在PostExecute方法中的变量中时，从PostExecute方法之外的方法或类进行访问时，它们始终是未分配的。我现在了解AsyncTask的工作原理，并且它是异步的。我尝试实现接口，然后尝试访问数据，但仍然无法。

GeoTask是我的Map类中的一个内部类。

public class GeoTask extends AsyncTask<String, Void, String> {
    ProgressDialog pd;
    Context mContext;

    SelectTime selectTime;



    //constructor is used to get the context.
    public GeoTask(Context mContext) {
        this.mContext = mContext;

    }

    public GeoTask() {
    }

    //This function is executed before before "doInBackground(String...params)" is executed to dispaly the progress dialog
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        selectTime=new SelectTime();
        pd=new ProgressDialog(mContext);
        pd.setMessage("Loading");
        pd.setCancelable(false);
        pd.show();
    }
    //This function is executed after the execution of "doInBackground(String...params)" to dismiss the dispalyed progress dialog and call "setDouble(Double)" defined in "MainActivity.java"
    @Override
    protected void onPostExecute(String aDouble) {
        super.onPostExecute(aDouble);
        if(aDouble!=null)
        {
            setDouble(aDouble);
        }
        else
            Toast.makeText(mContext, "Error4!Please Try Again with proper values", Toast.LENGTH_SHORT).show();
    }

    @Override
    protected String doInBackground(String... params) {
        try {
            URL url=new URL(params[0]);
            HttpURLConnection con= (HttpURLConnection) url.openConnection();
            con.setRequestMethod("GET");
            con.connect();
            int statuscode=con.getResponseCode();
            if(statuscode==HttpURLConnection.HTTP_OK)
            {
                BufferedReader br=new BufferedReader(new InputStreamReader(con.getInputStream()));
                StringBuilder sb=new StringBuilder();
                String line=br.readLine();
                while(line!=null)
                {
                    sb.append(line);
                    line=br.readLine();
                }
                String json=sb.toString();
                Log.d("JSON",json);
                JSONObject root=new JSONObject(json);
                JSONArray array_rows=root.getJSONArray("rows");
                Log.d("JSON","array_rows:"+array_rows);
                JSONObject object_rows=array_rows.getJSONObject(0);
                Log.d("JSON","object_rows:"+object_rows);
                JSONArray array_elements=object_rows.getJSONArray("elements");
                Log.d("JSON","array_elements:"+array_elements);
                JSONObject  object_elements=array_elements.getJSONObject(0);
                Log.d("JSON","object_elements:"+object_elements);
                JSONObject object_duration=object_elements.getJSONObject("duration");
                JSONObject object_distance=object_elements.getJSONObject("distance");

                Log.d("JSON","object_duration:"+object_duration);
                return object_duration.getString("value")+","+object_distance.getString("value");

            }
        } catch (MalformedURLException e) {
            Log.d("error", "error1");
        } catch (IOException e) {
            Log.d("error", "error2");
        } catch (JSONException e) {
            Log.d("error","error3");
        }


        return null;
    }


}

在Map类中，使用setDouble方法：

   public void setDouble(String result) {
    String res[] = result.split(",");
    Double m = Double.parseDouble(res[0]) / 60;
    Double d = Double.parseDouble(res[1])/1000;


    minutes=m
    distance=d


}

分钟和距离变量的初始化

private double minutes;

public double getMinutes() {
    return minutes;
}

private double distance;

public double getDistance() {
    return distance;
}

和执行：

 LatLng destinationLatLng = getLatLngFromAddress(destinationPassed);

    currentOrigin = getAddressFromLatLng(currentLat,currentLong);


    String url = "https://maps.googleapis.com/maps/api/distancematrix/json?origins=" + currentOrigin + "&destinations=" + destinationPassed + "&mode=walking&language=fr-FR&avoid=tolls&key=API_KEY";
    Log.d("url string",url);
    geoTask.execute(url);

此外，即使在PostExecution完成后，我也始终使用返回的值0.0来获取分钟和距离变量，即使在PostExecution完成后，我也始终获得值0.0（我使用Logs测试了它是否完成）

1）如何实现我想要的？访问API在不同类中返回的距离和持续时间？这对于我正在实现的应用程序至关重要。

2）如果使用AsyncTask和此方法无法实现所需的功能，是否可以不使用AsyncTask来使用Distance Matrix API？

Answer 1

可能您应该替换为您的>]

String url = "https://maps.googleapis.com/maps/api/distancematrix/json?origins=" + currentOrigin + "&destinations=" + destinationPassed + "&mode=walking&language=fr-FR&avoid=tolls&key=API_KEY";