JSON解析以在Google Map上将标记传递标记添加到URL

Question

I have an URL where i will parse some information including latitude longitude and show them in map. I have done parsing and added markers in the map too. But the markers are not displaying, only the map is displaying. At first i thought the link is broken but then i got the information that the URL won't give any return until i pass tag. Can anyone explain what does that mean?

Here is the URL and the sending data which includes the tag too. Can anyone make this clear to me,how can i do that? URL: "some url" Sending data: {"tag":"getAvailableDriver","lat":41.022348,"lng":-91.966721} Here is my code:

MainActivity.java

package com.hasibhasan.sampletask;

import java.util.ArrayList;
import java.util.List;

import org.json.JSONArray;
import org.json.JSONObject;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;

import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MainActivity extends ActionBarActivity {
    private GoogleMap googlemap;
    private static String TAG_POSTS = "posts";
    private static String TAG_DRIVER = "driver";
    private static String TAG_ID = "id";
    private static String TAG_LATITUDE = "lat";
    private static String TAG_LONGITUDE = "lon";
    private static String TAG_DATETIME = "recorded_datetime";
    private static String TAG_USERID = "user_id";
    private static String TAG_STATE = "cabby_state";
    private static String TAG_VTYPE = "vehicleType";
    private static String TAG_DRIVERNAME = "driver_name";
    private static String TAG_PICNAME = "pic_name";
    private static String TAG_RATING = "rating";
    private static String TAG_CARMODEL = "car_model";
    private static String TAG_NUMBERSIT = "number_sit";
    private static String TAG_DISTANCE = "distance";
    private static String TAG_OPERATOR = "operator";
    private static String TAG_NEARESTDISTANCE = "nearest_distance";
    private static String TAG_NDISTANCE = "distance";
    private static String TAG_TIME = "time";
    private static String TAG_CARMODELS = "car_models";
    ArrayList<Taxi> taxi;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        taxi = new ArrayList<Taxi>();
        new ParseJSONTask().execute();
        googlemap = ((MapFragment) getFragmentManager().findFragmentById(
                R.id.map)).getMap();

    }

    private class ParseJSONTask extends
            AsyncTask<Void, Void, List<MarkerOptions>> {
        @Override
        protected void onPreExecute() {

            super.onPreExecute();
        }

        @Override
        protected List<MarkerOptions> doInBackground(Void... params) {
            WebServiceHandler webServiceHandler = new WebServiceHandler();
            String jsonstr = webServiceHandler
                    .getJSONData("http://54.186.247.213/unicabi/mobileservice/CurrentLocationService.php");
            try {
                JSONObject jsonObject = new JSONObject(jsonstr);
                JSONArray postJson = jsonObject.getJSONArray(TAG_POSTS);
                List<MarkerOptions> markers = new ArrayList<MarkerOptions>();
                for (int i = 0; i < postJson.length(); i++) {
                    Taxi aTaxi = new Taxi();
                    JSONObject postObject = postJson.getJSONObject(i);
                    aTaxi.lat = postObject.getString(TAG_LATITUDE);
                    aTaxi.lon = postObject.getString(TAG_LONGITUDE);
                    aTaxi.driver_name = postObject.getString(TAG_DRIVERNAME);
                    // taxi.add(aTaxi);
                    double lati = Double.parseDouble(aTaxi.lat);
                    double lon = Double.parseDouble(aTaxi.lon);
                    markers.add(new MarkerOptions().title(aTaxi.driver_name)
                            .position(new LatLng(lati, lon)));

                    return markers;

                }

            } catch (Exception e) {
                e.printStackTrace();
            }
            return new ArrayList<MarkerOptions>();
        }

        @Override
        protected void onPostExecute(List<MarkerOptions> markers) {

            //super.onPostExecute(result);
            for (MarkerOptions marker : markers) {
                googlemap.addMarker(marker);
            }
        }
    }
}

WebHandlerService.java

package com.hasibhasan.sampletask;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

public class WebServiceHandler {
    public WebServiceHandler() {

    }

    public String getJSONData(String url) {
        String response = null;
        DefaultHttpClient httpclient = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet(url);
        HttpEntity httpEntity = null;
        HttpResponse httpResponse = null;
        try {
            httpResponse = httpclient.execute(httpGet);
            httpEntity = httpResponse.getEntity();
            response = EntityUtils.toString(httpEntity);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return response;

    }

}

Taxi.java

package com.hasibhasan.sampletask;

public class Taxi {
    public String posts = "";
    public String success = "";
    public String driver = "";
    public String id = "";
    public String lat = "";
    public String lon = "";
    public String recorded_datetime = "";
    public String vehicleType = "";
    public String driver_name = "";
    public String pic_name = "";
    public String rating = "";
    public String car_model = "";
    public String number_sit = "";
    public String distance = "";
    public String operator = "";
    public String nearest_distance = "";
    public String car_models = "";

}

I think the doInBackground is returning empty list as the url does not return anything to parse thus the PostExecute does not add any markers. can anybody figure this out? how to pass tag form the app to url when requesting so that the markers are being displayed. I am so lost.

Answer 1

http://54.186.247.213/unicabi/mobileservice/CurrentLocationService.php网址未返回jsonString ...请检查您是否从该网址获取json。

Answer 2

Yep the link has a problem

54.186.247.213/unicabi/mobileservice/CurrentLocationService.php

your php file should return basically json maybe you forget to encode your data to be in json.

example in php you should have something calling the method json_encode(your_data)