Create markers from JSON array php mySQL Google Ma

2019-03-21 19:34发布

站内文章 / Android
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问题:

I'm trying to create markers on Google Maps v2 from my mySQL database and it is not working. The map does come up but there are no markers. Can any one tell me what is wrong and what I need to change? I've also tried having the getDouble be getDouble(0) and getDouble(1) but I read somewhere to try 0 and 2. It also has a bunch of imports from multiple tutorials I've tried. I'll remove later.

My Activity

import com.google.android.gms.common.ConnectionResult;

import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Dialog;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.widget.TextView;

import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;


public class ReadComments extends FragmentActivity {
    private static final String LOG_TAG = "JsOn ErRoR";

    private static final String SERVICE_URL = "my url";

    protected GoogleMap mapB;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.get_local);
        setUpMapIfNeeded();
    }

    @Override
    protected void onResume() {
        super.onResume();
        setUpMapIfNeeded();
    }

    private void setUpMapIfNeeded() {
        if (mapB == null) {
            mapB = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.mapB))
                    .getMap();
            if (mapB != null) {
                setUpMap();
            }
        }
    }

    private void setUpMap() {

        new Thread(new Runnable() {
            public void run() {
                try {
                    retrieveAndAddCities();
                } catch (IOException e) {
                    Log.e(LOG_TAG, "Cannot retrive cities", e);
                    return;
                }
            }
        }).start();
    }

    protected void retrieveAndAddCities() throws IOException {
        HttpURLConnection conn = null;
        final StringBuilder json = new StringBuilder();
        try {
            // Connect to the web service
            URL url = new URL(SERVICE_URL);
            conn = (HttpURLConnection) url.openConnection();
            InputStreamReader in = new InputStreamReader(conn.getInputStream());

            // Read the JSON data into the StringBuilder
            int read;
            char[] buff = new char[1024];
            while ((read = in.read(buff)) != -1) {
                json.append(buff, 0, read);
            }
        } catch (IOException e) {
            Log.e(LOG_TAG, "Error connecting to service", e);
            throw new IOException("Error connecting to service", e);
        } finally {
            if (conn != null) {
                conn.disconnect();
            }
        }

        // Must run this on the UI thread since it's a UI operation.
        runOnUiThread(new Runnable() {
            public void run() {
                try {
                    createMarkersFromJson(json.toString());
                } catch (JSONException e) {
                    Log.e(LOG_TAG, "Error processing JSON", e);
                }
            }
        });
    }

    void createMarkersFromJson(String json) throws JSONException {

        JSONArray jsonArray = new JSONArray(json);

        List<Marker> markers = new ArrayList<Marker>();

        for (int i = 0; i < jsonArray.length(); i++) {

            JSONObject jsonObj = jsonArray.getJSONObject(i);
            Marker marker = mapB.addMarker(new MarkerOptions()
                .title(jsonObj.getString("business_name"))
                .position(new LatLng(
                        jsonObj.getJSONArray("latlng").getDouble(0),
                        jsonObj.getJSONArray("latlng").getDouble(2)
                 ))
            );
            markers.add(marker);
        }
    }
}

my JSON output from my url

    [{"business_name":"Wine Bar","latlng":["43.6894658949280400","-116.3533687591552700"],
"business_id":"2","distance":"23.0298400562551"},
{"business_name":"Apple Headquarters","latlng":["37.3324083200000000","-122.0304781500000000"],
"business_id":"3","distance":"23.0298400562551"}]

my Logcat (I do not know how to pull the whole log cat but these are the errors)

08-21 00:00:27.371: E/JsOn ErRoR(357):  at com..ReadComments.createMarkersFromJson(ReadComments.java:127)
08-21 00:00:27.371: E/JsOn ErRoR(357):  at com..ReadComments$2.run(ReadComments.java:107)

Partial Screenshot

回答1:

I've Got the right code here its working perfect. it has been updated to go to the current location as well because I've been messing with it since the fix.

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

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

import android.app.Dialog;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;


public class GetLocalBus extends FragmentActivity implements LocationListener {
    private static final String LOG_TAG = "JsOn ErRoR";

    private static final String SERVICE_URL = "";

    protected GoogleMap mapB;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.get_local);
        setUpMapIfNeeded();

     // Getting Google Play availability status
        int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(getBaseContext());

        // Showing status
        if(status!=ConnectionResult.SUCCESS){ // Google Play Services are not available

            int requestCode = 10;
            Dialog dialog = GooglePlayServicesUtil.getErrorDialog(status, this, requestCode);
            dialog.show();

        }else { // Google Play Services are available   

            // Getting reference to the SupportMapFragment of activity_main.xml
            SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.mapB);

            // Getting GoogleMap object from the fragment
            mapB = fm.getMap();

            // Enabling MyLocation Layer of Google Map
            mapB.setMyLocationEnabled(true); 



             // Getting LocationManager object from System Service LOCATION_SERVICE
            LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

            // Creating a criteria object to retrieve provider
            Criteria criteria = new Criteria();

            // Getting the name of the best provider
            String provider = locationManager.getBestProvider(criteria, true);

            // Getting Current Location
            Location location = locationManager.getLastKnownLocation(provider);

            if(location!=null){
                    onLocationChanged(location);
            }

            locationManager.requestLocationUpdates(provider, 20000, 0, this);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        setUpMapIfNeeded();
    }

    private void setUpMapIfNeeded() {
        if (mapB == null) {
            mapB = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.mapB))
                    .getMap();
            if (mapB != null) {
                setUpMap();
            }
        }
    }

    private void setUpMap() {

        new Thread(new Runnable() {
            public void run() {
                try {
                    retrieveAndAddCities();
                } catch (IOException e) {
                    Log.e(LOG_TAG, "Cannot retrive cities", e);
                    return;
                }
            }
        }).start();
    }

    protected void retrieveAndAddCities() throws IOException {
        HttpURLConnection conn = null;
        final StringBuilder json = new StringBuilder();
        try {
            // Connect to the web service
            URL url = new URL(SERVICE_URL);
            conn = (HttpURLConnection) url.openConnection();
            InputStreamReader in = new InputStreamReader(conn.getInputStream());

            // Read the JSON data into the StringBuilder
            int read;
            char[] buff = new char[1024];
            while ((read = in.read(buff)) != -1) {
                json.append(buff, 0, read);
            }
        } catch (IOException e) {
            Log.e(LOG_TAG, "Error connecting to service", e);
            throw new IOException("Error connecting to service", e);
        } finally {
            if (conn != null) {
                conn.disconnect();
            }
        }

        // Must run this on the UI thread since it's a UI operation.
        runOnUiThread(new Runnable() {
            public void run() {
                try {
                    createMarkersFromJson(json.toString());
                } catch (JSONException e) {
                    Log.e(LOG_TAG, "Error processing JSON", e);
                }
            }
        });
    }

    void createMarkersFromJson(String json) throws JSONException {

        JSONArray jsonArray = new JSONArray(json);
        System.out.print(json);
        List<Marker> markers = new ArrayList<Marker>();

        for (int i = 0; i < jsonArray.length(); i++) {

            JSONObject jsonObj = jsonArray.getJSONObject(i);
            System.out.print(jsonObj.getJSONArray("latlng"));
            Marker marker = mapB.addMarker(new MarkerOptions()
                .title(jsonObj.getString("business_name"))
                .position(new LatLng(
                        jsonObj.getJSONArray("latlng").getDouble(0),
                        jsonObj.getJSONArray("latlng").getDouble(1)))
                .icon(BitmapDescriptorFactory.fromResource(R.drawable.graphic_map_icon))
            );
            markers.add(marker);
        }
    }

    @Override
    public void onLocationChanged(Location location) {
        // Getting latitude of the current location
        double latitude = location.getLatitude();

        // Getting longitude of the current location
        double longitude = location.getLongitude();     

        // Creating a LatLng object for the current location
        LatLng latLng = new LatLng(latitude, longitude);

        // Showing the current location in Google Map
        mapB.moveCamera(CameraUpdateFactory.newLatLng(latLng));

        // Zoom in the Google Map
        mapB.animateCamera(CameraUpdateFactory.zoomTo(15));

    }

    @Override
    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }
}

Also here is the PHP

<?php




    if
    (isset($_GET['lat']) && isset($_GET['lon'])&& isset($_GET['dist'])){



    //make a simple database connection
        $db = new mysqli();



     $lat = $_GET['lat'];

         $lon = $_GET['lon'];

         $dist = $_GET['dist'];




        $search_sql = "SELECT business_id, business_name, CONCAT_WS(\",\",business_lat, business_lon) AS latlng, ( 3959 * acos( cos( radians(37) ) * cos( radians( " . $lat . " ) ) * cos( radians( " . $lon . " ) - radians(-122) ) + sin( radians(37) ) * sin( radians( " . $lat . " ) ) ) ) AS distance

                        FROM somewhere HAVING distance < " . $dist . " ORDER BY distance LIMIT 0 , 20";






        $search_results = $db->query($search_sql);



        if($search_results->num_rows){



     while ($row = $search_results->fetch_assoc())
{
    $return_data[] = array(
                            'business_name' => $row['business_name'],
                            'latlng'        => explode(',', $row['latlng']),
                            'business_id'   => $row['business_id'],
                            'distance'      => $row['distance']
                            );
}//end while


        }

        else{

            $return_data[] = array();

        }//end if




        }else{


        $return_data[] = array();

    }



    $bd_json = json_encode($return_data);



    $db->close();



    echo $bd_json;





?>

xml layout

    <fragment android:id="@+id/mapB" 
        android:layout_width="fill_parent" 
        android:layout_height="250.0dip" 
        android:layout_alignParentTop="true" 
        android:layout_centerInParent="true" 
        class="com.google.android.gms.maps.SupportMapFragment"
        xmlns:android="http://schemas.android.com/apk/res/android" />

    <TextView 
        android:id="@+id/TextView1" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" 
        android:layout_below="@+id/mapB" />
</RelativeLayout>


标签： android json google-maps mysqli google-maps-markers
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