如何在基于Google Map的应用中延迟onMapready调用 [英] How to delay onMapready call in Google map based app

问题描述

在我的Android应用程序中，我必须获取当前的GPS/网络位置，然后获取该位置的google地图.但是在获取位置之前，该地图已经加载并且每次获取(0,0)位置.我该如何延迟On mapready通话直到我获得位置.

In my android app i have to get the current GPS/network position and then get the google map of that position.But before getting the position, the map has been loaded and every time it gets (0,0) position.How can i delay the On mapready call till i get position.

代码

    package com.example.partha.map;

import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.util.Log;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private GoogleMap mMap;
    private  Position position;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);

        mapFragment.getMapAsync(this);
    }


    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
    @Override
    public void onMapReady(GoogleMap googleMap) {
        try {
            mMap = googleMap;

            // Add a marker in Sydney and move the camera

            position = new Position(this);
            position.getLocation(Position.NETWORK);
            LatLng sydney = new LatLng(position.getLatitude(),position.getLongitude());

            Log.d("position",position.getLatitude()+"   "+position.getLatitude());
            mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in your position"));
            Log.d("Added marker", " at position");
            mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
            Log.d("moved marker", " at position");
        }catch (Exception e)
        {
            Log.d("from on map",e.getMessage());
        }
    }
}

position.class

position.class

 public class Position {
        private boolean GPSPosition;
        private boolean networkPosition;
        private boolean SavedPosition;
        private Context context;
        private LatLng latLng;
        private double latitude;
        private double longitude;
        private LocationManager locationManager;
        private LocationListener listener;
        static public final int GPS = 2;
        static public final int NETWORK = 1;
        private float minDistance=5000;
        private long updateTime=0;


        public Position(Context context) {
            this.context = context;
            locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
            setListener();

        }

        public Position(Context context, float minDistance, long updateTime) {
            this.context = context;
            this.minDistance = minDistance;
            this.updateTime = updateTime;
        }

        public void setUpdateTime(long updateTime) {
            this.updateTime = updateTime;
        }

        public void setMinDistance(float minDistance) {
            this.minDistance = minDistance;
        }

        @TargetApi(Build.VERSION_CODES.M)
        public void getLocation(int source) {
            if (source == GPS) {
                if (ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                    // TODO: Consider calling
                    //    ActivityCompat#requestPermissions
                    // here to request the missing permissions, and then overriding

                    return;
                }
                else
                {
                    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, updateTime, minDistance, listener);
                }
            }
            else if(source==NETWORK)
            {

                locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,updateTime,minDistance,listener);
            }
        }

        public double getLongitude() {
            return longitude;
        }

        public double getLatitude() {
            return latitude;
        }

        public LatLng getLatLng() {
            return latLng;
        }

        private void setListener()
        {
            listener=new LocationListener() {
                @Override
                public void onLocationChanged(Location location) {

                    latitude=location.getLatitude();
                    longitude=location.getLongitude();
                    latLng=new LatLng(latitude,longitude);
                    Log.d("Your position",latitude+"    "+longitude);

                }

                @Override
                public void onStatusChanged(String provider, int status, Bundle extras) {

                }

                @Override
                public void onProviderEnabled(String provider) {

                }

                @Override
                public void onProviderDisabled(String provider) {
                    Intent settingsActivity = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                    context.startActivity(settingsActivity);

                }
            };
        }
    }

推荐答案

尝试以下操作:在调用getMapAsync之前获取latlng.删除在onMapReady方法中遇到的问题.

Try this : get latlng before calling getMapAsync. Remove getting latlng in onMapReady method.

 LatLng sydney;
protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);


  position = new Position(this);
            position.setListener();
            position.getLocation(Position.NETWORK);
             sydney = new LatLng(position.getLatitude(),position.getLongitude());

        mapFragment.getMapAsync(this);
    }

另一种方法是在Position类中创建一个接口，例如

Another way, create an interface in Position class like

public interface LocationListener{
void onSuccessLocation(Position position);
void onFailLocation();
}

并在您的活动中实施它.获取位置成功或失败时调用这些方法.然后onSuccessLocation()调用getMapAsync.

And implement it in your activity. call these method when get location successfully or failed. And onSuccessLocation() call getMapAsync.

在Position类的onLocationChanged方法中调用onSuccessLocation

In Position class onLocationChanged method call onSuccessLocation

public void onLocationChanged(Location location) {

                    latitude=location.getLatitude();
                    longitude=location.getLongitude();
                    latLng=new LatLng(latitude,longitude);
                    Log.d("Your position",latitude+"    "+longitude);
                    if(context != null){
                     ((LocationListener)context).onSuccessLocation(Position.this);
}
                }

这篇关于如何在基于Google Map的应用中延迟onMapready调用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！