具有当前位置的 Android 谷歌地图

Question

我正在编写一个应用程序，除其他事项外，它应该使用当前设备位置和远程点绘制地图。 我从 Android Studio 创建的示例开始（Google->Google Map Activity）。 我只是添加代码以获取当前位置：

package it.tux.mapper.activities;

import android.Manifest;
import android.annotation.SuppressLint;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

import androidx.annotation.NonNull;
import androidx.core.app.ActivityCompat;
import androidx.fragment.app.FragmentActivity;

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;
import com.google.android.material.snackbar.Snackbar;

import java.util.Objects;

import it.tux.mapper.R;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, ActivityCompat.OnRequestPermissionsResultCallback, LocationListener {
    private static final int PERMISSION_REQUEST_LOCATION = 11;
    private static final int LOCATION_UPDATE_DELAY = 1000;

    private final String gps_provider = LocationManager.GPS_PROVIDER;

    private GoogleMap map;
    private Location location;
    private LocationManager location_manager;
    private View layout;

    @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);

        if (mapFragment != null)
            mapFragment.getMapAsync(this);

        //USER CODE

        layout = findViewById(R.id.map);
        assert layout != null;

        location = new Location(getString(R.string.location_provider));
        location.isFromMockProvider();

        initLocalization();
        //
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        if (requestCode == PERMISSION_REQUEST_LOCATION) {
            if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                Snackbar.make(layout, R.string.fine_location_access_granted, Snackbar.LENGTH_SHORT).show();
                startLocalization();
            } else {
                Snackbar.make(layout, R.string.denied_fine_location_access_rationale, Snackbar.LENGTH_SHORT).show();
            }
        }
    }

    /**
     * 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) {
        map = googleMap;
    }

    @Override
    public void onLocationChanged(Location location) {
        this.location.set(location);

        if (map != null) {
            LatLng base = new LatLng(location.getLatitude(), location.getLongitude());
            map.addMarker(new MarkerOptions().position(base).title(getString(R.string.destination_base_label)));
            map.moveCamera(CameraUpdateFactory.newLatLng(base));
        }
    }

    @Override
    public void onStatusChanged(String s, int i, Bundle bundle) {
        return;
    }

    @Override
    public void onProviderEnabled(String s) {
        return;
    }

    @Override
    public void onProviderDisabled(String s) {
        return;
    }

    private void requestLocationPermission() {
        if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                Manifest.permission.ACCESS_FINE_LOCATION)) {
            Snackbar.make(layout, R.string.denied_fine_location_access_rationale,
                    Snackbar.LENGTH_INDEFINITE).setAction(R.string.ok, new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    ActivityCompat.requestPermissions(MapsActivity.this,
                            new String[]{Manifest.permission.CAMERA},
                            PERMISSION_REQUEST_LOCATION);
                }
            }).show();

        } else {
            Snackbar.make(layout, R.string.denied_fine_location_access_warning, Snackbar.LENGTH_SHORT).show();
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.CAMERA}, PERMISSION_REQUEST_LOCATION);
        }
    }

    private void initLocalization() {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            Snackbar.make(layout,
                    R.string.fine_location_access_granted,
                    Snackbar.LENGTH_SHORT).show();
            startLocalization();
        } else {
            requestLocationPermission();
        }
    }
    
    @SuppressLint("MissingPermission")
    private void startLocalization() {
        try {
            location_manager = (LocationManager) getSystemService(LOCATION_SERVICE);

            if (!location_manager.isProviderEnabled(gps_provider)) {
                Intent gpsOptionsIntent = new Intent(
                        android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                startActivity(gpsOptionsIntent);
            } else {
                location_manager.requestLocationUpdates(gps_provider, LOCATION_UPDATE_DELAY, 2, this);
            }
        } catch (Throwable e) {
            Log.e(getClass().getName(), "Exception: " + e.getMessage());
        }
    }
}

代码似乎工作，即没有触发异常，onMapReady、onLocationChanged 和onRequestPermissionsResult 事件被正确触发。 地图只是空的。 Api key的使用次数为0。

清单具有正确的权限条目：

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />

而且 GoogleApi 密钥设置正确（我有一个开发者帐户）：

    <meta-data
        android:name="com.google.android.geo.API_KEY"
        android:value="@string/google_maps_key" />

我的错误在哪里？

Answer 1

该问题似乎与用于首次连接到 google api 服务的 Internet 连接有关。在某些防火墙下，连接可能被阻止，无法成功授权。更改连接解决了这个问题，但我可能需要深入研究 API 身份验证机制。