java - 添加标记到 Google map - Android (JAVA)

Question

我正在尝试构建一个应用程序，它可以使用 Firebase 从实时数据库中检索经度和纬度。检索数据库中保存的位置后，我想添加一个显示空气质量指数(AQI)的标记。我尝试实现这个，但是 map 上没有标记，代码中也没有错误。 (它显示没有标记的 map )

这是我的数据库中的数据的样子:

my real time database using firebase

这是我的java代码:

 public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, LocationListener,GoogleMap.OnMarkerClickListener  {

private final String TAG = "TAG";
private static final int REQUEST_ACCESS_FINE_LOCATION = 13112;
private static final int REQUEST_CHECK_SETTINGS = 13119;

private boolean mLocationPermissionGranted;
private SupportMapFragment mSupportMapFragment;
private GoogleMap mGoogleMap;
private FusedLocationProviderClient mFusedLocationProviderClient;
private LocationRequest mLocationRequest;
private LocationCallback mLocationCallback;
private boolean mFirstRender = true;

private GoogleMap mMap;
private Marker mMarker;
private ChildEventListener mChildEventListener;
private DatabaseReference mUsers;



@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);
    } else {
        Toast.makeText(getApplicationContext(), "mapFragment != null", Toast.LENGTH_LONG).show();
    }
    ChildEventListener mChildEventListener;
    mUsers= FirebaseDatabase.getInstance().getReference("airvisual-e9c40");
    mUsers.push().setValue(mMarker);

    Window window = getWindow();
    window.setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS,
            WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);


    mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
    mSupportMapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mLocationCallback = new LocationCallback() {
        @Override
        public void onLocationResult(LocationResult locationResult) {

            if (locationResult == null) {
                return;
            }

            if (mMarker != null) {
                mMarker.remove();
            }

            for (final Location location : locationResult.getLocations()) {
                final LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
                mMarker = mGoogleMap.addMarker(new MarkerOptions().position(latLng)
                        .title("Lahore"));

               // mMarker.setIcon(BitmapDescriptorFactory.fromBitmap(mMarkerBitmap));

                CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(latLng, 17.0f);

                if (mFirstRender) {
                    mGoogleMap.animateCamera(cameraUpdate);
                    mFirstRender = false;
                }
            }
        }

        @Override
        public void onLocationAvailability(LocationAvailability locationAvailability) {
            super.onLocationAvailability(locationAvailability);
        }
    };

    getPermissions();

}


/**
 * 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.
 */

@SuppressLint("MissingPermission")
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    final LocationSettingsStates states = LocationSettingsStates.fromIntent(data);
    switch (requestCode) {
        case REQUEST_CHECK_SETTINGS:
            switch (resultCode) {
                case Activity.RESULT_OK:
                    // All required changes were successfully made
                    if (mLocationPermissionGranted) {
                        mFusedLocationProviderClient.requestLocationUpdates(mLocationRequest,
                                mLocationCallback, null);
                    }
                    break;
                case Activity.RESULT_CANCELED:
                    // The user was asked to change settings, but chose not to
                    new AlertDialog.Builder(MapsActivity.this)
                            .setTitle("Need Location")
                            .setMessage("Hi there! We can't show your current location without the" +
                                    " location service, could you please enable it?")
                            .setPositiveButton("Yep", new DialogInterface.OnClickListener() {
                                @RequiresApi(api = Build.VERSION_CODES.M)
                                @Override
                                public void onClick(DialogInterface dialogInterface, int i) {
                                    checkLocationAvailability();
                                }
                            })
                            .setNegativeButton("No thanks", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialogInterface, int i) {
                                    Toast.makeText(getApplicationContext(), ":(", Toast.LENGTH_LONG).show();
                                    finish();
                                }
                            }).show();
                    break;
                default:
                    break;
            }
            break;
    }
}

@Override
public void onRequestPermissionsResult(
        int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
        case REQUEST_ACCESS_FINE_LOCATION: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                // permission was granted, yay! Do what you want . . .
                mLocationPermissionGranted = true;
                mSupportMapFragment.getMapAsync(this);
            } else {
                // permission denied, boo! :(
                // Show an explanation to the user why this permission is required
                displayDialog();
            }

            return;
        }
    }
}

@SuppressLint("MissingPermission")
@Override
public void onMapReady(GoogleMap googleMap) {
    mGoogleMap = googleMap;

    googleMap.setOnMarkerClickListener(this);
    googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);

    messLocation();
}

private void messLocation() {

    DatabaseReference currentDBcordinates = FirebaseDatabase.getInstance().getReference().child("airvisual-e9c40");

    currentDBcordinates.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            //Create an array of markers
            int size = (int) dataSnapshot.getChildrenCount();
            Marker[] allMarkers = new Marker[size];
            mMap.clear();   //Assuming you're using mMap
            for(DataSnapshot s : dataSnapshot.getChildren()) {
                //Specify your model class here
                AQIModel cordinatesModel = new AQIModel();
                //lets create a loop
                for(int i=0;i<=size;i++) {
                    try {
                        Toast.makeText(getApplicationContext(), i, Toast.LENGTH_LONG).show();
                        //assuming you've set your getters and setters in the Model class
                        cordinatesModel.setLatitude(s.getValue(AQIModel.class).getLatitude());
                        cordinatesModel.setLongitude(s.getValue(AQIModel.class).getLongitude());
                        cordinatesModel.setAqi(s.getValue(AQIModel.class).getAqi());
                        //lets retrieve the coordinates and other information
                        Double latitude1 = cordinatesModel.getLatitude();
                        Double longitude1 = cordinatesModel.getLongitude();
                        String brandName=String.valueOf(cordinatesModel.getAqi());
                        //convert the coordinates to LatLng
                        LatLng latLng = new LatLng(latitude1, longitude1);
                        mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
                        //Now lets add updated markers

                        //lets add updated marker
                        allMarkers[i] = mMap.addMarker(new MarkerOptions()
                                .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED)).position(latLng).title(brandName));
                    }catch (Exception ex){}
                }


            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

private void checkLocationAvailability() {
    LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder();
    builder.addLocationRequest(mLocationRequest);

    SettingsClient settingsClient = LocationServices.getSettingsClient(this);
    Task<LocationSettingsResponse> task = settingsClient.checkLocationSettings(builder.build());
    task.addOnCompleteListener(new OnCompleteListener<LocationSettingsResponse>() {

        @SuppressLint("MissingPermission")
        @Override
        public void onComplete(@NonNull Task<LocationSettingsResponse> task) {
            try {
                LocationSettingsResponse response = task.getResult(ApiException.class);
                // All location settings are satisfied.
                if (mLocationPermissionGranted) {
                    mFusedLocationProviderClient.requestLocationUpdates(mLocationRequest,
                            mLocationCallback, null);
                }

            } catch (ApiException exception) {
                switch (exception.getStatusCode()) {
                    case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
                        // Location settings are not satisfied. But could be fixed by showing the
                        // user a dialog.
                        try {
                            // Cast to a resolvable exception.
                            ResolvableApiException resolvable = (ResolvableApiException) exception;
                            // Show the dialog by calling startResolutionForResult(),
                            // and check the result in onActivityResult().
                            resolvable.startResolutionForResult(
                                    MapsActivity.this,
                                    REQUEST_CHECK_SETTINGS);
                        } catch (IntentSender.SendIntentException e) {
                            // Ignore the error.
                        } catch (ClassCastException e) {
                            // Ignore, should be an impossible error.
                        }
                        break;
                    case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
                        // Location settings are not satisfied. However, we have no way to fix the
                        // settings so we won't show the dialog.
                        break;
                }
            }
        }
    });
}

private void getPermissions() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {

        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED) {

            // Permission is not granted
            if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                    Manifest.permission.ACCESS_FINE_LOCATION)) {

                // Show an explanation to the user why this permission is required
                displayDialog();
            } else {
                // No explanation needed; request the permission
                ActivityCompat.requestPermissions(this,
                        new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                        REQUEST_ACCESS_FINE_LOCATION);
            }
        } else {
            // Permission has already been granted
            mLocationPermissionGranted = true;
            mSupportMapFragment.getMapAsync(this);
        }
    } else {
        // Android SDK Version is below Marshmallow.
        // You don't need runtime permission, Do what you want . . .
        mLocationPermissionGranted = true;
        mSupportMapFragment.getMapAsync(this);
    }
}


private void displayDialog() {
    new AlertDialog.Builder(MapsActivity.this)
            .setTitle("Location Permission")
            .setMessage("Hi there! We can't show your current location without the" +
                    " location permission, could you please grant it?")
            .setPositiveButton("Yep", new DialogInterface.OnClickListener() {
                @RequiresApi(api = Build.VERSION_CODES.M)
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    requestPermissions(new String[]{
                                    Manifest.permission.ACCESS_FINE_LOCATION},
                            REQUEST_ACCESS_FINE_LOCATION);
                }
            })
            .setNegativeButton("No thanks", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    Toast.makeText(getApplicationContext(), ":(", Toast.LENGTH_LONG).show();
                    finish();
                }
            }).show();
}

@Override
public void onLocationChanged(Location location) {

}

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

}

@Override
public void onProviderEnabled(String provider) {

}

@Override
public void onProviderDisabled(String provider) {

}

@Override
public boolean onMarkerClick(Marker marker) {
    return false;
}
 }

我正在寻找这样的东西:

Expectations

Answer 1

将以下代码放入 OnMapReady 方法中。

ChildEventListener mChildEventListener;
    mUsers= FirebaseDatabase.getInstance().getReference("airvisual-e9c40");
    mUsers.push().setValue(mMarker);

    Window window = getWindow();
    window.setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS,
            WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);


    mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
    mSupportMapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mLocationCallback = new LocationCallback() {
        @Override
        public void onLocationResult(LocationResult locationResult) {

            if (locationResult == null) {
                return;
            }

            if (mMarker != null) {
                mMarker.remove();
            }

            for (final Location location : locationResult.getLocations()) {
                final LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
                mMarker = mGoogleMap.addMarker(new MarkerOptions().position(latLng)
                        .title("Lahore"));

               // mMarker.setIcon(BitmapDescriptorFactory.fromBitmap(mMarkerBitmap));

                CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(latLng, 17.0f);

                if (mFirstRender) {
                    mGoogleMap.animateCamera(cameraUpdate);
                    mFirstRender = false;
                }
            }
        }

        @Override
        public void onLocationAvailability(LocationAvailability locationAvailability) {
            super.onLocationAvailability(locationAvailability);
        }
    };

    getPermissions();

将所有逻辑写入onMapReady方法中。