Android GoogleMaps myLocation Permission

Question

使用更新版本的Android ...您应该在使用其位置信息之前检查用户是否已经授予您许可.我已经浏览了android文档,这是我提出的代码.

我正在检查用户是否已经给予了许可,如果他们还没有...那么我们会问,然后结果上有一个回调函数,依此类推.

我已经多次遍历代码并且一切似乎都工作正常除了:当我最终尝试以编程方式使用fusedLocationApi.getLastLocation获取用户的位置时......它返回NULL!

我重新上传了我的代码.

任何能够解决这个问题但实际上对我有用的人,你可以得到我所有的代表得分......

package com.example.greg.rightnow;


import android.content.pm.PackageManager;
import android.location.Location;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.support.v4.content.ContextCompat;
import android.Manifest;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.Api;
import com.google.android.gms.common.api.GoogleApiClient.ConnectionCallbacks;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.api.PendingResult;
import com.google.android.gms.common.api.Status;
import com.google.android.gms.drive.Drive;
import com.google.android.gms.location.LocationServices;
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.gms.plus.Plus;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.util.concurrent.TimeUnit;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, ConnectionCallbacks {

    private GoogleApiClient mGoogleApiClient;
    private GoogleMap mMap;
    private Location mLastLocation;


    @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);

        // Create an instance of GoogleAPIClient.
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(Drive.API)
                .addApi(Plus.API)
                .addScope(Drive.SCOPE_FILE)
                .addConnectionCallbacks(this)
        //        .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();


    }


    @Override
    public void onConnected(@Nullable Bundle bundle) {

        }





    protected void onStart() {
        mGoogleApiClient.connect();
        super.onStart();
    }

    protected void onStop() {
        mGoogleApiClient.disconnect();
        super.onStop();
    }




    /**
     * 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.
     * Manifest.permission.ACCESS_FINE_LOCATION
     */

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String permissions[], int[] grantResults) {


        if(ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == grantResults[0]) {
            mMap.setMyLocationEnabled(true);
        }


        mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);

        LatLng myLat = new LatLng(mLastLocation.getLatitude(), mLastLocation.getLongitude());
        // Add a marker in Sydney and move the camera
        LatLng sydney = new LatLng(-34, 151);
        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(myLat));


    }





    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;

        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                == 0) {

            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1);

        }

        else if(ContextCompat.checkSelfPermission(this,Manifest.permission.ACCESS_FINE_LOCATION) ==-1) {
            mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);

            LatLng myLat = new LatLng(mLastLocation.getLatitude(), mLastLocation.getLongitude());
            // Add a marker in Sydney and move the camera
            LatLng sydney = new LatLng(-34, 151);
            mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
            mMap.moveCamera(CameraUpdateFactory.newLatLng(myLat));


        }

    }

    @Override
    public void onConnectionSuspended(int i) {

    }
}

你会注意到我必须注释掉这一行:

 //   .addOnConnectionFailedListener(this)

如果我取消注释这个......'this'用红色加下划线,我得到一个错误,说"......在Builder中不能应用于com.example.greg.MapsActivity等"

Answer 1

检查权限后ContextCompat.checkSelfPermission,如果未授予权限,您可以请求它.从文档:

此外,您需要在使用GoogleApiClient(文档)时处理连接失败.在您的代码中,连接失败并且您没有对其进行管理onConnectionFailed.

最后,我从您的代码中删除了以下内容(这导致连接失败,无需使用LocationServices并获取最后一个位置):

.addApi(Drive.API)
.addApi(Plus.API)
.addScope(Drive.SCOPE_FILE)

这是一个工作示例:

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {
    private static final int FINE_LOCATION_PERMISSION_REQUEST = 1;
    private static final int CONNECTION_RESOLUTION_REQUEST = 2;
    private GoogleApiClient mGoogleApiClient;
    private GoogleMap mMap;
    private Location mLastLocation;

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

        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);

        buildGoogleAPIClient();
    }

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

        buildGoogleAPIClient();
    }

    private void buildGoogleAPIClient() {
        if (mGoogleApiClient == null) {
            mGoogleApiClient = new GoogleApiClient.Builder(this)
                    .addConnectionCallbacks(this)
                    .addOnConnectionFailedListener(this)
                    .addApi(LocationServices.API)
                    .build();
        }
    }

    @Override
    public void onConnected(@Nullable Bundle bundle) {
        findLocation();
    }

    protected void onStart() {
        mGoogleApiClient.connect();
        super.onStart();
    }

    protected void onStop() {
        mGoogleApiClient.disconnect();
        super.onStop();
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
    }

    @Override
    public void onConnectionSuspended(int i) {
        Toast.makeText(this, "Connection suspended", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onConnectionFailed(@NonNull final ConnectionResult connectionResult) {
        if (connectionResult.hasResolution()) {
            try {
                connectionResult.startResolutionForResult(this, CONNECTION_RESOLUTION_REQUEST);
            } catch (IntentSender.SendIntentException e) {
                // There was an error with the resolution intent. Try again.
                mGoogleApiClient.connect();
            }
        } else {
            Dialog dialog = GooglePlayServicesUtil.getErrorDialog(connectionResult.getErrorCode(), this, 1);
            dialog.show();
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode,
                                    Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == CONNECTION_RESOLUTION_REQUEST && resultCode == RESULT_OK) {
            mGoogleApiClient.connect();
        }
    }

    private void findLocation() {
        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                    FINE_LOCATION_PERMISSION_REQUEST);
        } else {
            mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);

            LatLng myLat = new LatLng(mLastLocation.getLatitude(), mLastLocation.getLongitude());
            // Add a marker in Sydney and move the camera
            LatLng sydney = new LatLng(-34, 151);
            mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
            mMap.moveCamera(CameraUpdateFactory.newLatLng(myLat));
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String permissions[], int[] grantResults) {
        switch (requestCode) {
            case FINE_LOCATION_PERMISSION_REQUEST: {
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    findLocation();
                }
            }
        }
    }
}