使用谷歌API在地图上获取当前位置的问题 [英] problem to get current location on map using google APIs

问题描述

下面的代码我写的是显示我当前的位置，但是当我运行我的应用程序时它显示白屏并暂时消失







它在线显示错误

调用需要用户可能拒绝的权限：代码应明确检查权限是否可用（使用checkPermission）或处理潜力SecurityException

below code i write to show my current location in but when run my application it show white screen for a while and disappear



it show error on line
Call requires permission which may be rejected by user: code should explicitly check to see if permission is available (with checkPermission) or handle a potential SecurityException

<pre lang="C#">Location myLocation = locationManager.getLastKnownLocation(provider);</pre>

also try the blow code but problem is same using API 21

<pre lang="java">

  if (ContextCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
                || ContextCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED)
        {


        }

package mapp2.ahmad.com.mapp2;

import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.support.v4.content.ContextCompat;

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.MarkerOptions;

public class MapsActivity extends FragmentActivity {

    private GoogleMap mMap; // Might be null if Google Play services APK is not available.

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

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

    /**
     * Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
     * installed) and the map has not already been instantiated.. This will ensure that we only ever
     * call {@link #setUpMap()} once when {@link #mMap} is not null.
     * <p/>
     * If it isn't installed {@link SupportMapFragment} (and
     * {@link com.google.android.gms.maps.MapView MapView}) will show a prompt for the user to
     * install/update the Google Play services APK on their device.
     * <p/>
     * A user can return to this FragmentActivity after following the prompt and correctly
     * installing/updating/enabling the Google Play services. Since the FragmentActivity may not
     * have been completely destroyed during this process (it is likely that it would only be
     * stopped or paused), {@link #onCreate(Bundle)} may not be called again so we should call this
     * method in {@link #onResume()} to guarantee that it will be called.
     */
    private void setUpMapIfNeeded() {
        // Do a null check to confirm that we have not already instantiated the map.
        if (mMap == null) {
            // Try to obtain the map from the SupportMapFragment.
            mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                    .getMap();
            // Check if we were successful in obtaining the map.
            if (mMap != null) {
                setUpMap();
            }
        }
    }

    /**
     * This is where we can add markers or lines, add listeners or move the camera. In this case, we
     * just add a marker near Africa.
     * <p/>
     * This should only be called once and when we are sure that {@link #mMap} is not null.
     */
    private void setUpMap() {
        mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker").snippet("Snippet"));

        // Enable MyLocation Layer of Google Map
        mMap.setMyLocationEnabled(true);

        // Get LocationManager object from System Service LOCATION_SERVICE
        LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

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

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

        // Get Current Location
      
        Location myLocation = locationManager.getLastKnownLocation(provider);

        // set map type
        mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);

        // Get latitude of the current location
        double latitude = myLocation.getLatitude();

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

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

        // Show the current location in Google Map
        mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

        // Zoom in the Google Map
        mMap.animateCamera(CameraUpdateFactory.zoomTo(14));
         mMap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).title("You are here!").snippet("Consider yourself located"));






    }
}

推荐答案

请遵循以下事项：

Android check LocationManager 的权限[ ^ ]

位置管理器删除更新权限 [< a href =http://stackoverflow.com/questions/32715189/location-manager-remove-updates-permissiontarget =_ blanktitle =New Window> ^ ]

Follow these things:
Android check permission for LocationManager[^]
Location Manager remove updates permission[^]

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