Hier wird beschrieben, wie Sie den aktuellen Standort eines Android-Geräts ermitteln und zu diesem Ort (einem Unternehmen oder POI) Details aufrufen können. In diesem Tutorial erfahren Sie, wie Sie mit dem Maps SDK for Android, dem Places SDK for Android und dem Anbieter für kombinierte Standortbestimmung aus den Standort-APIs der Google Play-Dienste eine Android-App erstellen.
Code abrufen
So sieht die Java-Version der Aktivität aus:
// Copyright 2020 Google LLC // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package com.example.currentplacedetailsonmap; import android.content.DialogInterface; import android.content.pm.PackageManager; import android.location.Location; import android.os.Bundle; import android.util.Log; import android.util.TypedValue; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.FrameLayout; import android.widget.TextView; import android.widget.Toast; import androidx.annotation.NonNull; import androidx.appcompat.app.AlertDialog; import androidx.appcompat.app.AppCompatActivity; import androidx.core.app.ActivityCompat; import androidx.core.content.ContextCompat; import androidx.core.graphics.Insets; import androidx.core.view.ViewCompat; import androidx.core.view.WindowInsetsCompat; import com.google.android.gms.location.FusedLocationProviderClient; 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.CameraPosition; import com.google.android.gms.maps.model.LatLng; import com.google.android.gms.maps.model.Marker; import com.google.android.gms.maps.model.MarkerOptions; import com.google.android.gms.tasks.OnCompleteListener; import com.google.android.gms.tasks.Task; import com.google.android.libraries.places.api.Places; import com.google.android.libraries.places.api.model.CircularBounds; import com.google.android.libraries.places.api.model.Place; import com.google.android.libraries.places.api.net.PlacesClient; import com.google.android.libraries.places.api.net.SearchNearbyRequest; import com.google.android.libraries.places.api.net.SearchNearbyResponse; import java.util.ArrayList; import java.util.Arrays; import java.util.List; /** An activity that displays a map showing the place at the device's current location. */ public class MapsActivityCurrentPlace extends AppCompatActivity implements OnMapReadyCallback { private static final String TAG = MapsActivityCurrentPlace.class.getSimpleName(); private GoogleMap map; private CameraPosition cameraPosition; // The entry point to the Places API. private PlacesClient placesClient; // The entry point to the Fused Location Provider. private FusedLocationProviderClient fusedLocationProviderClient; // A default location (Sydney, Australia) and default zoom to use when location permission is // not granted. private final LatLng defaultLocation = new LatLng(-33.8523341, 151.2106085); private static final int DEFAULT_ZOOM = 15; private static final int PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION = 1; private boolean locationPermissionGranted; // The geographical location where the device is currently located. That is, the last-known // location retrieved by the Fused Location Provider or set via long press. Location lastKnownLocation; // Keys for storing activity state. private static final String KEY_CAMERA_POSITION = "camera_position"; private static final String KEY_LOCATION = "location"; // Used for selecting the current place. private static final int M_MAX_ENTRIES = 5; private static final double SEARCH_RADIUS_METERS = 100.0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Retrieve location and camera position from saved instance state. if (savedInstanceState != null) { lastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION); cameraPosition = savedInstanceState.getParcelable(KEY_CAMERA_POSITION); } // Retrieve the content view that renders the map. setContentView(R.layout.activity_maps); ViewCompat.setOnApplyWindowInsetsListener( getWindow().getDecorView(), (v, insets) -> { Insets systemBars = insets.getInsets( WindowInsetsCompat.Type.systemBars() | WindowInsetsCompat.Type.displayCutout()); View actionBarContainer = getWindow() .getDecorView() .findViewById(androidx.appcompat.R.id.action_bar_container); if (actionBarContainer != null) { actionBarContainer.setPadding( actionBarContainer.getPaddingLeft(), systemBars.top, actionBarContainer.getPaddingRight(), actionBarContainer.getPaddingBottom()); } TypedValue typedValue = new TypedValue(); int actionBarHeight = getTheme() .resolveAttribute( android.R.attr.actionBarSize, typedValue, true) ? TypedValue.complexToDimensionPixelSize( typedValue.data, getResources().getDisplayMetrics()) : 0; if (map != null) { map.setPadding(0, systemBars.top + actionBarHeight, 0, systemBars.bottom); } return insets; }); // Construct a PlacesClient Places.initializeWithNewPlacesApiEnabled(getApplicationContext(), BuildConfig.MAPS_API_KEY); placesClient = Places.createClient(this); // Construct a FusedLocationProviderClient. fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this); // Build the map. SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map); mapFragment.getMapAsync(this); } /** Saves the state of the map when the activity is paused. */ @Override protected void onSaveInstanceState(Bundle outState) { if (map != null) { outState.putParcelable(KEY_CAMERA_POSITION, map.getCameraPosition()); outState.putParcelable(KEY_LOCATION, lastKnownLocation); } super.onSaveInstanceState(outState); } /** * Sets up the options menu. * * @param menu The options menu. * @return Boolean. */ @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.current_place_menu, menu); return true; } /** * Handles a click on the menu option to get a place. * * @param item The menu item to handle. * @return Boolean. */ @Override public boolean onOptionsItemSelected(MenuItem item) { if (item.getItemId() == R.id.option_get_place) { showCurrentPlace(); } return true; } /** * Manipulates the map when it's available. This callback is triggered when the map is ready to * be used. */ @Override public void onMapReady(GoogleMap map) { this.map = map; // Use a custom info window adapter to handle multiple lines of text in the // info window contents. this.map.setInfoWindowAdapter( new GoogleMap.InfoWindowAdapter() { @Override // Return null here, so that getInfoContents() is called next. public View getInfoWindow(Marker arg0) { return null; } @Override public View getInfoContents(Marker marker) { // Inflate the layouts for the info window, title and snippet. View infoWindow = getLayoutInflater() .inflate( R.layout.custom_info_contents, (FrameLayout) findViewById(R.id.map), false); TextView title = infoWindow.findViewById(R.id.title); title.setText(marker.getTitle()); TextView snippet = infoWindow.findViewById(R.id.snippet); snippet.setText(marker.getSnippet()); return infoWindow; } }); // Allow moving the current location with a long press on the map to easily // demo and discover nearby places anywhere in the world. this.map.setOnMapLongClickListener(this::setCustomLocation); // Prompt the user for permission. getLocationPermission(); WindowInsetsCompat rootInsets = ViewCompat.getRootWindowInsets(getWindow().getDecorView()); if (rootInsets != null) { Insets systemBars = rootInsets.getInsets( WindowInsetsCompat.Type.systemBars() | WindowInsetsCompat.Type.displayCutout()); TypedValue typedValue = new TypedValue(); int actionBarHeight = getTheme().resolveAttribute(android.R.attr.actionBarSize, typedValue, true) ? TypedValue.complexToDimensionPixelSize( typedValue.data, getResources().getDisplayMetrics()) : 0; this.map.setPadding(0, systemBars.top + actionBarHeight, 0, systemBars.bottom); } // Turn on the My Location layer and the related control on the map. updateLocationUI(); // Get the current location of the device and set the position of the map. getDeviceLocation(); } /** Gets the current location of the device, and positions the map's camera. */ private void getDeviceLocation() { /* * Get the best and most recent location of the device, which may be null in rare * cases when a location is not available. */ try { if (locationPermissionGranted) { Task<Location> locationResult = fusedLocationProviderClient.getLastLocation(); locationResult.addOnCompleteListener( this, new OnCompleteListener<Location>() { @Override public void onComplete(@NonNull Task<Location> task) { if (task.isSuccessful()) { // Set the map's camera position to the current location of the // device. lastKnownLocation = task.getResult(); if (lastKnownLocation != null) { map.moveCamera( CameraUpdateFactory.newLatLngZoom( new LatLng( lastKnownLocation.getLatitude(), lastKnownLocation.getLongitude()), DEFAULT_ZOOM)); } } else { Log.d(TAG, "Current location is null. Using defaults."); Log.e(TAG, "Exception: %s", task.getException()); map.moveCamera( CameraUpdateFactory.newLatLngZoom( defaultLocation, DEFAULT_ZOOM)); map.getUiSettings().setMyLocationButtonEnabled(false); } } }); } } catch (SecurityException e) { Log.e("Exception: %s", e.getMessage(), e); } } /** Prompts the user for permission to use the device location. */ private void getLocationPermission() { /* * Request location permission, so that we can get the location of the * device. The result of the permission request is handled by a callback, * onRequestPermissionsResult. */ if (ContextCompat.checkSelfPermission( this.getApplicationContext(), android.Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) { locationPermissionGranted = true; } else { ActivityCompat.requestPermissions( this, new String[] {android.Manifest.permission.ACCESS_FINE_LOCATION}, PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION); } } /** Handles the result of the request for location permissions. */ @Override public void onRequestPermissionsResult( int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) { locationPermissionGranted = false; if (requestCode == PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION) { // If request is cancelled, the // result arrays are empty. if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { locationPermissionGranted = true; } } else { super.onRequestPermissionsResult(requestCode, permissions, grantResults); } updateLocationUI(); } /** * UI representation of a place item to display in the selection dialog and map marker. * * <p>It is good practice to decouple the external data/backend model ({@link Place}) from the * UI layer. The UI should be as free of logic as possible: it receives presentation-ready data * (non-null coordinates, ready-to-display title and snippet strings) so that dialogs and map * overlays remain simple, predictable, and testable. */ static class PlaceItemUiModel { final String title; final String snippet; final LatLng position; PlaceItemUiModel(String title, String snippet, LatLng position) { this.title = title; this.snippet = snippet; this.position = position; } } /** * Maps an external {@link Place} domain model into a display-ready {@link PlaceItemUiModel}. * * <p>The mapper encapsulates all data normalization, default value fallbacks (such as fallback * titles), and string formatting (such as appending third-party attributions to the address). * Keeping this transformation logic in the mapper prevents business and formatting logic from * leaking into the UI components. Returns {@code null} if essential coordinates are missing. */ private PlaceItemUiModel toUiModel(Place place) { return toUiModel(place, getString(R.string.default_info_title)); } static PlaceItemUiModel toUiModel(Place place, String defaultTitle) { if (place.getLocation() == null) { return null; } String title = place.getDisplayName() != null ? place.getDisplayName() : defaultTitle; StringBuilder snippet = new StringBuilder(); if (place.getFormattedAddress() != null) { snippet.append(place.getFormattedAddress()); } if (place.getAttributions() != null && !place.getAttributions().isEmpty()) { if (snippet.length() > 0) { snippet.append("\n"); } snippet.append(String.join("\n", place.getAttributions())); } return new PlaceItemUiModel(title, snippet.toString(), place.getLocation()); } /** * Prompts the user to select the current place from a list of likely places, and shows the * current place on the map - provided the user has granted location permission. */ private void showCurrentPlace() { if (map == null) { return; } if (lastKnownLocation != null && "manual".equals(lastKnownLocation.getProvider())) { locationPermissionGranted = true; } if (locationPermissionGranted) { // Use fields to define the data types to return. List<Place.Field> placeFields = Arrays.asList( Place.Field.DISPLAY_NAME, Place.Field.FORMATTED_ADDRESS, Place.Field.LOCATION); // Search around the device's last-known location, falling back to the center of the // map if the location is not available yet. LatLng center = lastKnownLocation != null ? new LatLng( lastKnownLocation.getLatitude(), lastKnownLocation.getLongitude()) : map.getCameraPosition().target; CircularBounds searchArea = CircularBounds.newInstance(center, SEARCH_RADIUS_METERS); // Use the builder to create a SearchNearbyRequest that returns the closest places // first. SearchNearbyRequest request = SearchNearbyRequest.builder(searchArea, placeFields) .setMaxResultCount(M_MAX_ENTRIES) .setRankPreference(SearchNearbyRequest.RankPreference.DISTANCE) .build(); // Get the likely places - that is, the businesses and other points of interest that // are closest to the device's current location. final Task<SearchNearbyResponse> placeResult = placesClient.searchNearby(request); placeResult.addOnCompleteListener( new OnCompleteListener<SearchNearbyResponse>() { @Override public void onComplete(@NonNull Task<SearchNearbyResponse> task) { if (task.isSuccessful() && task.getResult() != null) { List<Place> responsePlaces = task.getResult().getPlaces(); int count = Math.min(responsePlaces.size(), M_MAX_ENTRIES); List<PlaceItemUiModel> likelyPlaces = new ArrayList<>(); for (int i = 0; i < count; i++) { PlaceItemUiModel model = toUiModel(responsePlaces.get(i)); if (model != null) { likelyPlaces.add(model); } } // Show a dialog offering the user the list of likely places, and // add a marker at the selected place. MapsActivityCurrentPlace.this.openPlacesDialog(likelyPlaces); } else { Log.e(TAG, "Exception: %s", task.getException()); } } }); } else { // The user has not granted permission. Log.i(TAG, "The user did not grant location permission."); // Add a default marker, because the user hasn't selected a place. map.addMarker( new MarkerOptions() .title(getString(R.string.default_info_title)) .position(defaultLocation) .snippet(getString(R.string.default_info_snippet))); // Prompt the user for permission. getLocationPermission(); } } /** Displays a form allowing the user to select a place from a list of likely places. */ void openPlacesDialog(List<PlaceItemUiModel> likelyPlaces) { if (likelyPlaces.isEmpty()) { Toast.makeText( this, "No places found nearby. Long-press on the map to choose another location.", Toast.LENGTH_LONG) .show(); return; } // Ask the user to choose the place where they are now. DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { // The "which" argument contains the position of the selected item. PlaceItemUiModel selectedPlace = likelyPlaces.get(which); // Add a marker for the selected place, with an info window // showing information about that place. map.addMarker( new MarkerOptions() .title(selectedPlace.title) .position(selectedPlace.position) .snippet(selectedPlace.snippet)); // Position the map's camera at the location of the marker. map.moveCamera( CameraUpdateFactory.newLatLngZoom( selectedPlace.position, DEFAULT_ZOOM)); } }; // Display the dialog. String[] titles = new String[likelyPlaces.size()]; for (int i = 0; i < likelyPlaces.size(); i++) { titles[i] = likelyPlaces.get(i).title; } new AlertDialog.Builder(this) .setTitle(R.string.pick_place) .setItems(titles, listener) .show(); } /** Updates the map's UI settings based on whether the user has granted location permission. */ private void updateLocationUI() { if (map == null) { return; } try { if (locationPermissionGranted) { map.setMyLocationEnabled(true); map.getUiSettings().setMyLocationButtonEnabled(true); } else { map.setMyLocationEnabled(false); map.getUiSettings().setMyLocationButtonEnabled(false); lastKnownLocation = null; } } catch (SecurityException e) { Log.e("Exception: %s", e.getMessage()); } } /** Updates the current location and searches for places around the specified coordinate. */ void setCustomLocation(LatLng latLng) { Location location = new Location("manual"); location.setLatitude(latLng.latitude); location.setLongitude(latLng.longitude); lastKnownLocation = location; if (map != null) { map.animateCamera(CameraUpdateFactory.newLatLng(latLng)); } showCurrentPlace(); } }
Die Kotlin-Version der Aktivität sieht so aus:
// Copyright 2020 Google LLC // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package com.example.currentplacedetailsonmap import android.Manifest import android.annotation.SuppressLint import android.content.DialogInterface import android.content.pm.PackageManager import android.location.Location import android.os.Bundle import android.util.Log import android.util.TypedValue import android.view.Menu import android.view.MenuItem import android.view.View import android.widget.FrameLayout import android.widget.TextView import android.widget.Toast import androidx.appcompat.app.AlertDialog import androidx.appcompat.app.AppCompatActivity import androidx.core.app.ActivityCompat import androidx.core.content.ContextCompat import androidx.core.view.ViewCompat import androidx.core.view.WindowInsetsCompat import com.google.android.gms.location.FusedLocationProviderClient 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.GoogleMap.InfoWindowAdapter import com.google.android.gms.maps.OnMapReadyCallback import com.google.android.gms.maps.SupportMapFragment import com.google.android.gms.maps.model.CameraPosition import com.google.android.gms.maps.model.LatLng import com.google.android.gms.maps.model.Marker import com.google.android.gms.maps.model.MarkerOptions import com.google.android.libraries.places.api.Places import com.google.android.libraries.places.api.model.CircularBounds import com.google.android.libraries.places.api.model.Place import com.google.android.libraries.places.api.net.PlacesClient import com.google.android.libraries.places.api.net.SearchNearbyRequest /** * An activity that displays a map showing the place at the device's current location. */ class MapsActivityCurrentPlace : AppCompatActivity(), OnMapReadyCallback { private var map: GoogleMap? = null private var cameraPosition: CameraPosition? = null internal var selectedMarker: Marker? = null // The entry point to the Places API. private lateinit var placesClient: PlacesClient // The entry point to the Fused Location Provider. private lateinit var fusedLocationProviderClient: FusedLocationProviderClient // A default location (Sydney, Australia) and default zoom to use when location permission is // not granted. private val defaultLocation = LatLng(-33.8523341, 151.2106085) private var locationPermissionGranted = false // The geographical location where the device is currently located. That is, the last-known // location retrieved by the Fused Location Provider or set via long press. internal var lastKnownLocation: Location? = null override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) // Retrieve location and camera position from saved instance state. if (savedInstanceState != null) { lastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION) cameraPosition = savedInstanceState.getParcelable(KEY_CAMERA_POSITION) } // Retrieve the content view that renders the map. setContentView(R.layout.activity_maps) ViewCompat.setOnApplyWindowInsetsListener(window.decorView) { _, insets -> val systemBars = insets.getInsets( WindowInsetsCompat.Type.systemBars() or WindowInsetsCompat.Type.displayCutout(), ) val actionBarContainer = window.decorView.findViewById<View>(androidx.appcompat.R.id.action_bar_container) actionBarContainer?.setPadding( actionBarContainer.paddingLeft, systemBars.top, actionBarContainer.paddingRight, actionBarContainer.paddingBottom, ) val typedValue = TypedValue() val actionBarHeight = if (theme.resolveAttribute(android.R.attr.actionBarSize, typedValue, true)) { TypedValue.complexToDimensionPixelSize(typedValue.data, resources.displayMetrics) } else { 0 } map?.setPadding(0, systemBars.top + actionBarHeight, 0, systemBars.bottom) insets } // Construct a PlacesClient Places.initializeWithNewPlacesApiEnabled(applicationContext, BuildConfig.MAPS_API_KEY) placesClient = Places.createClient(this) // Construct a FusedLocationProviderClient. fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this) // Build the map. val mapFragment = supportFragmentManager .findFragmentById(R.id.map) as SupportMapFragment? mapFragment?.getMapAsync(this) } /** * Saves the state of the map when the activity is paused. */ override fun onSaveInstanceState(outState: Bundle) { map?.let { map -> outState.putParcelable(KEY_CAMERA_POSITION, map.cameraPosition) outState.putParcelable(KEY_LOCATION, lastKnownLocation) } super.onSaveInstanceState(outState) } /** * Sets up the options menu. * @param menu The options menu. * @return Boolean. */ override fun onCreateOptionsMenu(menu: Menu): Boolean { menuInflater.inflate(R.menu.current_place_menu, menu) return true } /** * Handles a click on the menu option to get a place. * @param item The menu item to handle. * @return Boolean. */ override fun onOptionsItemSelected(item: MenuItem): Boolean { if (item.itemId == R.id.option_get_place) { showCurrentPlace() } return true } /** * Manipulates the map when it's available. * This callback is triggered when the map is ready to be used. */ override fun onMapReady(map: GoogleMap) { this.map = map // Use a custom info window adapter to handle multiple lines of text in the // info window contents. this.map?.setInfoWindowAdapter(object : InfoWindowAdapter { // Return null here, so that getInfoContents() is called next. override fun getInfoWindow(arg0: Marker): View? = null override fun getInfoContents(marker: Marker): View { // Inflate the layouts for the info window, title and snippet. val infoWindow = layoutInflater.inflate( R.layout.custom_info_contents, findViewById<FrameLayout>(R.id.map), false, ) val title = infoWindow.findViewById<TextView>(R.id.title) title.text = marker.title val snippet = infoWindow.findViewById<TextView>(R.id.snippet) snippet.text = marker.snippet return infoWindow } }) // Allow moving the current location with a long press on the map to easily // demo and discover nearby places anywhere in the world. this.map?.setOnMapLongClickListener { latLng -> setCustomLocation(latLng) } // Prompt the user for permission. getLocationPermission() val insets = ViewCompat.getRootWindowInsets(window.decorView) ?.getInsets(WindowInsetsCompat.Type.systemBars() or WindowInsetsCompat.Type.displayCutout()) val topInset = insets?.top ?: 0 val bottomInset = insets?.bottom ?: 0 val typedValue = TypedValue() val actionBarHeight = if (theme.resolveAttribute(android.R.attr.actionBarSize, typedValue, true)) { TypedValue.complexToDimensionPixelSize(typedValue.data, resources.displayMetrics) } else { 0 } this.map?.setPadding(0, topInset + actionBarHeight, 0, bottomInset) // Turn on the My Location layer and the related control on the map. updateLocationUI() // Get the current location of the device and set the position of the map. getDeviceLocation() } /** * Gets the current location of the device, and positions the map's camera. */ @SuppressLint("MissingPermission") private fun getDeviceLocation() { /* * Get the best and most recent location of the device, which may be null in rare * cases when a location is not available. */ try { if (locationPermissionGranted) { val locationResult = fusedLocationProviderClient.lastLocation locationResult.addOnCompleteListener(this) { task -> if (task.isSuccessful) { // Set the map's camera position to the current location of the device. lastKnownLocation = task.result if (lastKnownLocation != null) { map?.moveCamera( CameraUpdateFactory.newLatLngZoom( LatLng( lastKnownLocation!!.latitude, lastKnownLocation!!.longitude, ), DEFAULT_ZOOM.toFloat(), ), ) } } else { Log.d(TAG, "Current location is null. Using defaults.") Log.e(TAG, "Exception: %s", task.exception) map?.moveCamera( CameraUpdateFactory .newLatLngZoom(defaultLocation, DEFAULT_ZOOM.toFloat()), ) map?.uiSettings?.isMyLocationButtonEnabled = false } } } } catch (e: SecurityException) { Log.e("Exception: %s", e.message, e) } } /** * Prompts the user for permission to use the device location. */ private fun getLocationPermission() { /* * Request location permission, so that we can get the location of the * device. The result of the permission request is handled by a callback, * onRequestPermissionsResult. */ if (ContextCompat.checkSelfPermission( this.applicationContext, Manifest.permission.ACCESS_FINE_LOCATION, ) == PackageManager.PERMISSION_GRANTED ) { locationPermissionGranted = true } else { ActivityCompat.requestPermissions( this, arrayOf(Manifest.permission.ACCESS_FINE_LOCATION), PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION, ) } } /** * Handles the result of the request for location permissions. */ override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) { locationPermissionGranted = false when (requestCode) { PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION -> { // If request is cancelled, the result arrays are empty. if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED ) { locationPermissionGranted = true } } else -> super.onRequestPermissionsResult(requestCode, permissions, grantResults) } updateLocationUI() } private fun Place.toUiModel(): PlaceItemUiModel? = toPlaceItemUiModel(this, getString(R.string.default_info_title)) /** * Prompts the user to select the current place from a list of likely places, and shows the * current place on the map - provided the user has granted location permission. */ private fun showCurrentPlace() { val map = map ?: return if (lastKnownLocation?.provider == "manual") { locationPermissionGranted = true } if (locationPermissionGranted) { // Use fields to define the data types to return. val placeFields = listOf( Place.Field.DISPLAY_NAME, Place.Field.FORMATTED_ADDRESS, Place.Field.LOCATION, ) // Search around the device's last-known location, falling back to the center of // the map if the location is not available yet. val center = lastKnownLocation?.let { LatLng(it.latitude, it.longitude) } ?: map.cameraPosition.target val searchArea = CircularBounds.newInstance(center, SEARCH_RADIUS_METERS) // Use the builder to create a SearchNearbyRequest that returns the closest places // first. val request = SearchNearbyRequest.builder(searchArea, placeFields) .setMaxResultCount(M_MAX_ENTRIES) .setRankPreference(SearchNearbyRequest.RankPreference.DISTANCE) .build() // Get the likely places - that is, the businesses and other points of interest that // are closest to the device's current location. val placeResult = placesClient.searchNearby(request) placeResult.addOnCompleteListener { task -> if (task.isSuccessful && task.result != null) { val likelyPlaces = task.result.places .take(M_MAX_ENTRIES) .mapNotNull { it.toUiModel() } // Show a dialog offering the user the list of likely places, and add a // marker at the selected place. openPlacesDialog(likelyPlaces) } else { Log.e(TAG, "Exception: %s", task.exception) } } } else { // The user has not granted permission. Log.i(TAG, "The user did not grant location permission.") // Add a default marker, because the user hasn't selected a place. map.addMarker( MarkerOptions() .title(getString(R.string.default_info_title)) .position(defaultLocation) .snippet(getString(R.string.default_info_snippet)), ) // Prompt the user for permission. getLocationPermission() } } /** * Displays a form allowing the user to select a place from a list of likely places. */ internal fun openPlacesDialog(likelyPlaces: List<PlaceItemUiModel>) { if (likelyPlaces.isEmpty()) { Toast.makeText( this, "No places found nearby. Long-press on the map to choose another location.", Toast.LENGTH_LONG, ).show() return } // Ask the user to choose the place where they are now. val listener = DialogInterface.OnClickListener { _, which -> // The "which" argument contains the position of the selected item. val selectedPlace = likelyPlaces[which] // Add a marker for the selected place, with an info window // showing information about that place. selectedMarker = map?.addMarker( MarkerOptions() .title(selectedPlace.title) .position(selectedPlace.position) .snippet(selectedPlace.snippet), ) // Position the map's camera at the location of the marker. map?.moveCamera( CameraUpdateFactory.newLatLngZoom( selectedPlace.position, DEFAULT_ZOOM.toFloat(), ), ) } // Display the dialog. val titles = likelyPlaces.map { it.title }.toTypedArray() AlertDialog.Builder(this) .setTitle(R.string.pick_place) .setItems(titles, listener) .show() } /** * Updates the map's UI settings based on whether the user has granted location permission. */ @SuppressLint("MissingPermission") private fun updateLocationUI() { if (map == null) { return } try { if (locationPermissionGranted) { map?.isMyLocationEnabled = true map?.uiSettings?.isMyLocationButtonEnabled = true } else { map?.isMyLocationEnabled = false map?.uiSettings?.isMyLocationButtonEnabled = false lastKnownLocation = null getLocationPermission() } } catch (e: SecurityException) { Log.e("Exception: %s", e.message, e) } } /** * Updates the current location and searches for places around the specified coordinate. */ internal fun setCustomLocation(latLng: LatLng) { val location = Location("manual").apply { latitude = latLng.latitude longitude = latLng.longitude } lastKnownLocation = location map?.animateCamera(CameraUpdateFactory.newLatLng(latLng)) showCurrentPlace() } companion object { private val TAG = MapsActivityCurrentPlace::class.java.simpleName private const val DEFAULT_ZOOM = 15 private const val PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION = 1 // Keys for storing activity state. private const val KEY_CAMERA_POSITION = "camera_position" private const val KEY_LOCATION = "location" // Used for selecting the current place. private const val M_MAX_ENTRIES = 5 private const val SEARCH_RADIUS_METERS = 100.0 } } /** * UI representation of a place item to display in the selection dialog and map marker. * * It is good practice to decouple the external data/backend model ([Place]) from the UI layer. * The UI should be as free of logic as possible: it receives presentation-ready data (non-null * coordinates, ready-to-display title and snippet strings) so that dialogs and map overlays * remain simple, predictable, and testable. */ internal data class PlaceItemUiModel(val title: String, val snippet: String, val position: LatLng) /** * Maps an external [Place] domain model into a display-ready [PlaceItemUiModel]. * * The mapper encapsulates all data normalization, default value fallbacks (such as fallback * titles), and string formatting (such as appending third-party attributions to the address). * Keeping this transformation logic in the mapper prevents business and formatting logic * from leaking into the UI components. Returns `null` if essential coordinates are missing. */ internal fun toPlaceItemUiModel(place: Place, defaultTitle: String): PlaceItemUiModel? { val position = place.location ?: return null val title = place.displayName ?: defaultTitle val snippet = buildString { place.formattedAddress?.let { append(it) } place.attributions?.takeIf { it.isNotEmpty() }?.let { if (isNotEmpty()) append("\n") append(it.joinToString("\n")) } } return PlaceItemUiModel(title = title, snippet = snippet, position = position) }
Entwicklungsprojekt einrichten
Führen Sie die folgenden Schritte aus, um das Tutorial-Projekt in Android Studio zu erstellen.
- Laden Sie Android Studio herunter und installieren Sie es.
- Fügen Sie das Paket Google Play-Dienste in Android Studio ein.
- Klonen Sie das Repository „Google Maps Android API v2 Samples“ oder laden Sie es herunter, sofern Sie das nicht schon zu Beginn dieses Tutorials getan haben.
Importieren Sie das Tutorial-Projekt:
- Wählen Sie in Android Studio File > New > Import Project aus.
- Gehen Sie zu dem Speicherort, an dem Sie das Repository „Google Maps Android API v2 Samples“ nach dem Download gespeichert haben.
- Suchen Sie nach dem Projekt CurrentPlaceDetailsOnMap unter:
PATH-TO-SAVED-REPO/android-samples/tutorials/java/CurrentPlaceDetailsOnMap(Java) oder
PATH-TO-SAVED-REPO/android-samples/tutorials/kotlin/CurrentPlaceDetailsOnMap(Kotlin). - Wählen Sie das Projektverzeichnis aus und klicken Sie auf Open. Ihr Projekt wird jetzt mit dem Build-Tool Gradle in Android Studio erstellt.
Erforderliche APIs aktivieren und API-Schlüssel anfordern
Als letzten Schritt benötigen Sie noch ein Google Cloud-Projekt mit den erforderlichen, aktivierten APIs und einen API-Schlüssel, der zum Verwenden des Maps SDK for Android berechtigt. Weitere Informationen finden Sie hier:
Wenn Sie die aktivierten APIs sehen möchten, rufen Sie in der Cloud Console die Seite „Google Maps Platform“ auf und wählen Sie Ihr Projekt aus:
Zur Seite „Google Maps Platform“Wenn die Places API in Ihrem Projekt nicht aktiviert ist, holen Sie diesen Schritt nach:
Places API aktivierenFalls Sie Einschränkungen für Ihren API-Schlüssel festlegen, müssen Sie ihm die Places API hinzufügen. Weitere Informationen finden Sie unter API-Schlüssel verwenden.
API-Schlüssel in die App einfügen
- Öffnen Sie die
local.properties-Datei Ihres Projekts. Fügen Sie den folgenden String ein und ersetzen Sie dabei
YOUR_API_KEYdurch den Wert Ihres API-Schlüssels:MAPS_API_KEY=YOUR_API_KEY
Wenn Sie Ihre App erstellen, wird der API-Schlüssel über das Secrets Gradle-Plug-in für Android kopiert und dann als Build-Variable im Android-Manifest zur Verfügung gestellt. Dies wird weiter unten genauer beschrieben.
App erstellen und ausführen
Verbinden Sie ein Android-Gerät mit Ihrem Computer. Folgen Sie dieser Anleitung, um Entwickleroptionen auf Ihrem Android-Gerät zu aktivieren und Ihr System so zu konfigurieren, dass das Gerät erkannt wird.
Alternativ können Sie mit Android Virtual Device (AVD) Manager ein virtuelles Gerät konfigurieren. Beim Auswählen eines Emulators sollten Sie ein Image angeben, das die Google-APIs enthält. Weitere Informationen finden Sie unter Android Studio-Projekt einrichten.
- Klicken Sie in Android Studio auf die Menüoption Run (oder das Wiedergabesymbol). Wählen Sie ein Gerät aus, wenn Sie dazu aufgefordert werden.
In Android Studio wird Gradle aufgerufen, um die App zu erstellen. Dann wird die App auf dem Gerät oder im Emulator ausgeführt. Nun sollte eine Karte mit einer Reihe von Markierungen zu sehen sein, die um Ihren aktuellen Standort herum angeordnet sind – ähnlich wie auf dem Bild auf dieser Seite.
- Wählen Sie Get Place aus, um eine Liste mit Orten (Unternehmen oder anderen POIs) in der Nähe Ihres aktuellen Standorts zu öffnen. Damit Sie die Liste der Orte sehen können, müssen Sie die Berechtigung zur Standortermittlung erteilen, wenn Sie dazu aufgefordert werden.
- Wählen Sie in der Liste einen Ort aus. In der Karte wird für den ausgewählten Ort eine Markierung eingefügt.
Fehlerbehebung:
- Wenn Sie keine Karte sehen, prüfen Sie, ob Sie einen API-Schlüssel erhalten und ihn wie oben beschrieben in die App eingefügt haben. Kontrollieren Sie, ob es im Log im Android Monitor von Android Studio Fehlermeldungen zum API-Schlüssel gibt.
- Wenn auf der Karte nur eine einzelne Markierung auf der Sydney Harbour Bridge (dem in der App angegebenen standardmäßigen Standort) angezeigt wird, prüfen Sie, ob Sie der App eine Berechtigung zur Standortermittlung zugewiesen haben. Die App fordert diese Berechtigung zur Laufzeit an. Dabei wird das im Leitfaden zu Android-Berechtigungen beschriebene Muster befolgt. Sie können Berechtigungen auch direkt auf dem Gerät festlegen, indem Sie Einstellungen > Apps > App-Name > Berechtigungen > Standort auswählen. Ausführliche Informationen zum Umgang mit Berechtigungen in Ihrem Code finden Sie unten im Abschnitt Berechtigung zur Standortermittlung anfordern.
- Wenn Sie Logs aufrufen und Fehler in der App beheben möchten, können Sie dazu die Debugging-Tools in Android Studio verwenden.
Code verstehen
In diesem Teil des Tutorials werden die wichtigsten Teile der App CurrentPlaceDetailsOnMap erläutert, damit Sie besser verstehen, wie Sie eine ähnliche App erstellen können.
Places API-Client instanziieren
Die folgenden Objekte sind die primären Einstiegspunkte für das Places SDK for Android:
- Mit der Klasse
Placeswerden Clients für das Places SDK for Android erstellt und verwaltet. - Über die Schnittstelle
PlacesClientwerden der aktuelle Standort des Geräts sowie die Orte in der Nähe des Standorts abgerufen.
Die Schnittstelle LocationServices ist der Haupteinstiegspunkt für Android-Standortdienste.
Wenn Sie die APIs nutzen möchten, führen Sie in der onCreate()-Methode des Fragments oder der Aktivität folgende Schritte aus:
- Initialisieren Sie ein
Places-Objekt. - Erstellen Sie ein
PlacesClient-Objekt. - Erstellen Sie ein
FusedLocationProviderClient-Objekt.
Beispiel:
Java
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // ... // Retrieve the content view that renders the map. setContentView(R.layout.activity_maps); // Construct a PlacesClient Places.initialize(getApplicationContext(), getString(R.string.maps_api_key)); placesClient = Places.createClient(this); // Construct a FusedLocationProviderClient. fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this); }
Kotlin
override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) // ... // Retrieve the content view that renders the map. setContentView(R.layout.activity_maps) // Construct a PlacesClient Places.initialize(applicationContext, getString(R.string.maps_api_key)) placesClient = Places.createClient(this) // Construct a FusedLocationProviderClient. fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this) }
Berechtigung zur Standortermittlung anfordern
Um den Gerätestandort bestimmen und die Funktion zum Antippen des Buttons Mein Standort auf der Karte für Nutzer freigeben zu können, muss über Ihre App eine Berechtigung zur Standortermittlung angefordert werden.
Dieses Tutorial enthält den Code, den Sie zum Anfordern einer detaillierten Berechtigung zur Standortermittlung benötigen. Weitere Informationen finden Sie im Leitfaden zu Android-Berechtigungen.
Fügen Sie die Berechtigung als untergeordnetes Element des Elements
<manifest>in Ihrem Android-Manifest hinzu:<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.currentplacedetailsonmap"> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> </manifest>
Fordern Sie in Ihrer App Laufzeitberechtigungen an und geben Sie dem Nutzer die Möglichkeit, die Berechtigung zur Standortermittlung zu erteilen oder abzulehnen. Mit dem folgenden Code wird überprüft, ob der Nutzer eine gültige Berechtigung zur Standortermittlung erteilt hat. Falls nicht, wird die Berechtigung angefordert:
Java
private void getLocationPermission() { /* * Request location permission, so that we can get the location of the * device. The result of the permission request is handled by a callback, * onRequestPermissionsResult. */ if (ContextCompat.checkSelfPermission( this.getApplicationContext(), android.Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) { locationPermissionGranted = true; } else { ActivityCompat.requestPermissions( this, new String[] {android.Manifest.permission.ACCESS_FINE_LOCATION}, PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION); } }
Kotlin
private fun getLocationPermission() { /* * Request location permission, so that we can get the location of the * device. The result of the permission request is handled by a callback, * onRequestPermissionsResult. */ if (ContextCompat.checkSelfPermission( this.applicationContext, Manifest.permission.ACCESS_FINE_LOCATION, ) == PackageManager.PERMISSION_GRANTED ) { locationPermissionGranted = true } else { ActivityCompat.requestPermissions( this, arrayOf(Manifest.permission.ACCESS_FINE_LOCATION), PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION, ) } }
Überschreiben Sie den Callback
onRequestPermissionsResult(), um das Ergebnis der Berechtigungsanfrage zu verarbeiten:Java
@Override public void onRequestPermissionsResult( int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) { locationPermissionGranted = false; if (requestCode == PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION) { // If request is cancelled, the // result arrays are empty. if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { locationPermissionGranted = true; } } else { super.onRequestPermissionsResult(requestCode, permissions, grantResults); } updateLocationUI(); }
Kotlin
override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) { locationPermissionGranted = false when (requestCode) { PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION -> { // If request is cancelled, the result arrays are empty. if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED ) { locationPermissionGranted = true } } else -> super.onRequestPermissionsResult(requestCode, permissions, grantResults) } updateLocationUI() }
In einem späteren Abschnitt dieses Tutorials wird die
updateLocationUI()-Methode beschrieben.
Karte hinzufügen
Rufen Sie mit dem Maps SDK for Android eine Karte auf.
Fügen Sie der Layoutdatei
activity_maps.xmlIhrer Aktivität ein<fragment>-Element hinzu. Mit diesem Element wird einSupportMapFragmentdefiniert, das als Container für die Karte fungiert und Zugriff auf dasGoogleMap-Objekt bietet. In diesem Tutorial wird die Version der Android Support Library des Kartenfragments verwendet, um die Abwärtskompatibilität mit früheren Versionen des Android-Frameworks sicherzustellen.<!-- Copyright 2020 Google LLC Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> <fragment xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/map" android:name="com.google.android.gms.maps.SupportMapFragment" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.currentplacedetailsonmap.MapsActivityCurrentPlace" />
Legen Sie in der
onCreate()-Methode die Layoutdatei als Inhaltsansicht fest:Java
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Retrieve the content view that renders the map. setContentView(R.layout.activity_maps); }
Kotlin
override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) // Retrieve the content view that renders the map. setContentView(R.layout.activity_maps) }
Implementieren Sie die Schnittstelle
OnMapReadyCallbackund überschreiben Sie dieonMapReady()-Methode, um die Karte einzurichten, wenn dasGoogleMap-Objekt verfügbar ist:Java
@Override public void onMapReady(GoogleMap map) { this.map = map; // ... // Turn on the My Location layer and the related control on the map. updateLocationUI(); // Get the current location of the device and set the position of the map. getDeviceLocation(); }
Kotlin
override fun onMapReady(map: GoogleMap) { this.map = map // ... // Turn on the My Location layer and the related control on the map. updateLocationUI() // Get the current location of the device and set the position of the map. getDeviceLocation() }
Rufen Sie in der
onCreate()-Methode Ihrer Aktivität einen Handle zum Kartenfragment ab, indem SieFragmentManager.findFragmentById()aufrufen. Registrieren Sie sich dann mitgetMapAsync()für den Karten-Callback:Java
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map); mapFragment.getMapAsync(this);
Kotlin
val mapFragment = supportFragmentManager .findFragmentById(R.id.map) as SupportMapFragment? mapFragment?.getMapAsync(this)
Schreiben Sie eine
updateLocationUI()-Methode, um die Standortsteuerelemente auf der Karte festzulegen. Wenn der Nutzer die Berechtigung zur Standortermittlung erteilt hat, aktivieren Sie die Ebene „Mein Standort“ und das entsprechende Steuerelement auf der Karte. Deaktivieren Sie andernfalls die Ebene und das Steuerelement und setzen Sie den aktuellen Standort auf „null“:Java
private void updateLocationUI() { if (map == null) { return; } try { if (locationPermissionGranted) { map.setMyLocationEnabled(true); map.getUiSettings().setMyLocationButtonEnabled(true); } else { map.setMyLocationEnabled(false); map.getUiSettings().setMyLocationButtonEnabled(false); lastKnownLocation = null; } } catch (SecurityException e) { Log.e("Exception: %s", e.getMessage()); } }
Kotlin
@SuppressLint("MissingPermission") private fun updateLocationUI() { if (map == null) { return } try { if (locationPermissionGranted) { map?.isMyLocationEnabled = true map?.uiSettings?.isMyLocationButtonEnabled = true } else { map?.isMyLocationEnabled = false map?.uiSettings?.isMyLocationButtonEnabled = false lastKnownLocation = null getLocationPermission() } } catch (e: SecurityException) { Log.e("Exception: %s", e.message, e) } }
Standort des Android-Geräts abrufen und Karte positionieren
Verwenden Sie den Anbieter für kombinierte Standortbestimmung, um den zuletzt bekannten Standort des Geräts zu finden, und nutzen Sie den Standort dann, um die Karte zu positionieren. Dieses Tutorial enthält den Code, den Sie benötigen. Weitere Informationen zum Abrufen des Gerätestandorts finden Sie in der Referenz zur FusedLocationProviderApi in den Standort-APIs der Google Play-Dienste.
Java
private void getDeviceLocation() { /* * Get the best and most recent location of the device, which may be null in rare * cases when a location is not available. */ try { if (locationPermissionGranted) { Task<Location> locationResult = fusedLocationProviderClient.getLastLocation(); locationResult.addOnCompleteListener( this, new OnCompleteListener<Location>() { @Override public void onComplete(@NonNull Task<Location> task) { if (task.isSuccessful()) { // Set the map's camera position to the current location of the // device. lastKnownLocation = task.getResult(); if (lastKnownLocation != null) { map.moveCamera( CameraUpdateFactory.newLatLngZoom( new LatLng( lastKnownLocation.getLatitude(), lastKnownLocation.getLongitude()), DEFAULT_ZOOM)); } } else { Log.d(TAG, "Current location is null. Using defaults."); Log.e(TAG, "Exception: %s", task.getException()); map.moveCamera( CameraUpdateFactory.newLatLngZoom( defaultLocation, DEFAULT_ZOOM)); map.getUiSettings().setMyLocationButtonEnabled(false); } } }); } } catch (SecurityException e) { Log.e("Exception: %s", e.getMessage(), e); } }
Kotlin
@SuppressLint("MissingPermission") private fun getDeviceLocation() { /* * Get the best and most recent location of the device, which may be null in rare * cases when a location is not available. */ try { if (locationPermissionGranted) { val locationResult = fusedLocationProviderClient.lastLocation locationResult.addOnCompleteListener(this) { task -> if (task.isSuccessful) { // Set the map's camera position to the current location of the device. lastKnownLocation = task.result if (lastKnownLocation != null) { map?.moveCamera( CameraUpdateFactory.newLatLngZoom( LatLng( lastKnownLocation!!.latitude, lastKnownLocation!!.longitude, ), DEFAULT_ZOOM.toFloat(), ), ) } } else { Log.d(TAG, "Current location is null. Using defaults.") Log.e(TAG, "Exception: %s", task.exception) map?.moveCamera( CameraUpdateFactory .newLatLngZoom(defaultLocation, DEFAULT_ZOOM.toFloat()), ) map?.uiSettings?.isMyLocationButtonEnabled = false } } } } catch (e: SecurityException) { Log.e("Exception: %s", e.message, e) } }
Aktuellen Ort abrufen
Verwenden Sie das Places SDK for Android, um eine Liste von Orten abzurufen, die sich möglicherweise am aktuellen Standort befinden. In diesem Zusammenhang ist ein Ort ein Unternehmen oder ein anderer POI.
In diesem Tutorial wird der aktuelle Ort abgerufen, wenn der Nutzer auf den Button zum Abrufen des Ortes klickt. Dem Nutzer wird daraufhin eine Liste mit möglichen Orten zur Auswahl angezeigt. Wenn er einen Ort ausgewählt hat, wird an dessen Position eine Markierung erstellt. Das Tutorial enthält den Code, den Sie für die Interaktion mit dem Places SDK for Android benötigen. Weitere Informationen finden Sie in der Anleitung zum Abrufen des aktuellen Orts.
- Erstellen Sie eine Layoutdatei (
current_place_menu.xml) für das Optionsmenü und überschreiben Sie dieonCreateOptionsMenu()-Methode, um das Optionsmenü einzurichten. Entsprechenden Code finden Sie in der zugehörigen Beispiel-App. - Überschreiben Sie die
onOptionsItemSelected()-Methode, um den aktuellen Ort abzurufen, wenn der Nutzer auf die Option zum Abrufen des Standorts klickt:Java
@Override public boolean onOptionsItemSelected(MenuItem item) { if (item.getItemId() == R.id.option_get_place) { showCurrentPlace(); } return true; }
Kotlin
override fun onOptionsItemSelected(item: MenuItem): Boolean { if (item.itemId == R.id.option_get_place) { showCurrentPlace() } return true }
Erstellen Sie eine
showCurrentPlace()-Methode, um eine Liste mit Orten abzurufen, die sich möglicherweise am aktuellen Standort befinden:Java
private void showCurrentPlace() { if (map == null) { return; } // ... if (locationPermissionGranted) { // Use fields to define the data types to return. List<Place.Field> placeFields = Arrays.asList( Place.Field.DISPLAY_NAME, Place.Field.FORMATTED_ADDRESS, Place.Field.LOCATION); // Search around the device's last-known location, falling back to the center of the // map if the location is not available yet. LatLng center = lastKnownLocation != null ? new LatLng( lastKnownLocation.getLatitude(), lastKnownLocation.getLongitude()) : map.getCameraPosition().target; CircularBounds searchArea = CircularBounds.newInstance(center, SEARCH_RADIUS_METERS); // Use the builder to create a SearchNearbyRequest that returns the closest places // first. SearchNearbyRequest request = SearchNearbyRequest.builder(searchArea, placeFields) .setMaxResultCount(M_MAX_ENTRIES) .setRankPreference(SearchNearbyRequest.RankPreference.DISTANCE) .build(); // Get the likely places - that is, the businesses and other points of interest that // are closest to the device's current location. final Task<SearchNearbyResponse> placeResult = placesClient.searchNearby(request); placeResult.addOnCompleteListener( new OnCompleteListener<SearchNearbyResponse>() { @Override public void onComplete(@NonNull Task<SearchNearbyResponse> task) { if (task.isSuccessful() && task.getResult() != null) { List<Place> responsePlaces = task.getResult().getPlaces(); int count = Math.min(responsePlaces.size(), M_MAX_ENTRIES); List<PlaceItemUiModel> likelyPlaces = new ArrayList<>(); for (int i = 0; i < count; i++) { PlaceItemUiModel model = toUiModel(responsePlaces.get(i)); if (model != null) { likelyPlaces.add(model); } } // Show a dialog offering the user the list of likely places, and // add a marker at the selected place. MapsActivityCurrentPlace.this.openPlacesDialog(likelyPlaces); } else { Log.e(TAG, "Exception: %s", task.getException()); } } }); } else { // The user has not granted permission. Log.i(TAG, "The user did not grant location permission."); // Add a default marker, because the user hasn't selected a place. map.addMarker( new MarkerOptions() .title(getString(R.string.default_info_title)) .position(defaultLocation) .snippet(getString(R.string.default_info_snippet))); // Prompt the user for permission. getLocationPermission(); } }
Kotlin
private fun showCurrentPlace() { val map = map ?: return // ... if (locationPermissionGranted) { // Use fields to define the data types to return. val placeFields = listOf( Place.Field.DISPLAY_NAME, Place.Field.FORMATTED_ADDRESS, Place.Field.LOCATION, ) // Search around the device's last-known location, falling back to the center of // the map if the location is not available yet. val center = lastKnownLocation?.let { LatLng(it.latitude, it.longitude) } ?: map.cameraPosition.target val searchArea = CircularBounds.newInstance(center, SEARCH_RADIUS_METERS) // Use the builder to create a SearchNearbyRequest that returns the closest places // first. val request = SearchNearbyRequest.builder(searchArea, placeFields) .setMaxResultCount(M_MAX_ENTRIES) .setRankPreference(SearchNearbyRequest.RankPreference.DISTANCE) .build() // Get the likely places - that is, the businesses and other points of interest that // are closest to the device's current location. val placeResult = placesClient.searchNearby(request) placeResult.addOnCompleteListener { task -> if (task.isSuccessful && task.result != null) { val likelyPlaces = task.result.places .take(M_MAX_ENTRIES) .mapNotNull { it.toUiModel() } // Show a dialog offering the user the list of likely places, and add a // marker at the selected place. openPlacesDialog(likelyPlaces) } else { Log.e(TAG, "Exception: %s", task.exception) } } } else { // The user has not granted permission. Log.i(TAG, "The user did not grant location permission.") // Add a default marker, because the user hasn't selected a place. map.addMarker( MarkerOptions() .title(getString(R.string.default_info_title)) .position(defaultLocation) .snippet(getString(R.string.default_info_snippet)), ) // Prompt the user for permission. getLocationPermission() } }
Erstellen Sie eine
openPlacesDialog()-Methode, um ein Formular einzublenden, über das der Nutzer einen Ort aus einer Liste möglicher Orte auswählen kann. Erstellen Sie auf der Karte eine Markierung für den ausgewählten Ort. Die Markierung enthält den Namen und die Adresse des Orts sowie alle Quellenangaben, die von der API zur Verfügung gestellt werden:Java
void openPlacesDialog(List<PlaceItemUiModel> likelyPlaces) { // ... // Ask the user to choose the place where they are now. DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { // The "which" argument contains the position of the selected item. PlaceItemUiModel selectedPlace = likelyPlaces.get(which); // Add a marker for the selected place, with an info window // showing information about that place. map.addMarker( new MarkerOptions() .title(selectedPlace.title) .position(selectedPlace.position) .snippet(selectedPlace.snippet)); // Position the map's camera at the location of the marker. map.moveCamera( CameraUpdateFactory.newLatLngZoom( selectedPlace.position, DEFAULT_ZOOM)); } }; // Display the dialog. String[] titles = new String[likelyPlaces.size()]; for (int i = 0; i < likelyPlaces.size(); i++) { titles[i] = likelyPlaces.get(i).title; } new AlertDialog.Builder(this) .setTitle(R.string.pick_place) .setItems(titles, listener) .show(); }
Kotlin
internal fun openPlacesDialog(likelyPlaces: List<PlaceItemUiModel>) { // ... // Ask the user to choose the place where they are now. val listener = DialogInterface.OnClickListener { _, which -> // The "which" argument contains the position of the selected item. val selectedPlace = likelyPlaces[which] // Add a marker for the selected place, with an info window // showing information about that place. selectedMarker = map?.addMarker( MarkerOptions() .title(selectedPlace.title) .position(selectedPlace.position) .snippet(selectedPlace.snippet), ) // Position the map's camera at the location of the marker. map?.moveCamera( CameraUpdateFactory.newLatLngZoom( selectedPlace.position, DEFAULT_ZOOM.toFloat(), ), ) } // Display the dialog. val titles = likelyPlaces.map { it.title }.toTypedArray() AlertDialog.Builder(this) .setTitle(R.string.pick_place) .setItems(titles, listener) .show() }
Erstellen Sie ein benutzerdefiniertes Layout für den Inhalt des Infofensters. Dadurch erhalten Sie in diesem Fenster mehrere Inhaltszeilen. Fügen Sie zuerst die XML-Layoutdatei
custom_info_contents.xmlhinzu, die eine Textansicht für den Titel des Infofensters enthält, und dann eine weitere Textansicht für das Snippet, also den Textinhalt dieses Fensters:<?xml version="1.0" encoding="utf-8"?> <!-- Copyright 2020 Google LLC Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layoutDirection="locale" android:orientation="vertical"> <TextView android:id="@+id/title" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:textColor="#ff000000" android:textStyle="bold" /> <TextView android:id="@+id/snippet" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textColor="#ff7f7f7f" /> </LinearLayout>
Implementieren Sie die Schnittstelle
InfoWindowAdapter, um eine Layout-Inflation durchzuführen und den Inhalt des Infofensters zu laden.Java
// Use a custom info window adapter to handle multiple lines of text in the // info window contents. this.map.setInfoWindowAdapter( new GoogleMap.InfoWindowAdapter() { @Override // Return null here, so that getInfoContents() is called next. public View getInfoWindow(Marker arg0) { return null; } @Override public View getInfoContents(Marker marker) { // Inflate the layouts for the info window, title and snippet. View infoWindow = getLayoutInflater() .inflate( R.layout.custom_info_contents, (FrameLayout) findViewById(R.id.map), false); TextView title = infoWindow.findViewById(R.id.title); title.setText(marker.getTitle()); TextView snippet = infoWindow.findViewById(R.id.snippet); snippet.setText(marker.getSnippet()); return infoWindow; } });
Kotlin
// Use a custom info window adapter to handle multiple lines of text in the // info window contents. this.map?.setInfoWindowAdapter(object : InfoWindowAdapter { // Return null here, so that getInfoContents() is called next. override fun getInfoWindow(arg0: Marker): View? = null override fun getInfoContents(marker: Marker): View { // Inflate the layouts for the info window, title and snippet. val infoWindow = layoutInflater.inflate( R.layout.custom_info_contents, findViewById<FrameLayout>(R.id.map), false, ) val title = infoWindow.findViewById<TextView>(R.id.title) title.text = marker.title val snippet = infoWindow.findViewById<TextView>(R.id.snippet) snippet.text = marker.snippet return infoWindow } })
Status der Karte speichern
Speichern Sie die Kameraposition und den Gerätestandort. Wenn ein Nutzer ein Android-Gerät dreht oder die Konfiguration ändert, wird die Kartenaktivität durch das Android-Framework zerstört und wieder neu erstellt. Damit dieser Ablauf flüssiger wird, sollten Sie den Status der relevanten App speichern und bei Bedarf wiederherstellen.
Im vorliegenden Tutorial finden Sie den gesamten Code, der erforderlich ist, um den Status der Karte zu speichern. Weitere Informationen finden Sie in der Anleitung zum savedInstanceState-Paket.
Richten Sie in Ihrer Kartenaktivität Schlüssel/Wert-Paare ein, um den Status der Aktivität zu speichern:
Java
private static final String KEY_CAMERA_POSITION = "camera_position"; private static final String KEY_LOCATION = "location";
Kotlin
private const val KEY_CAMERA_POSITION = "camera_position" private const val KEY_LOCATION = "location"
Implementieren Sie den
onSaveInstanceState()-Callback, um den Status zu speichern, wenn die Aktivität pausiert:Java
@Override protected void onSaveInstanceState(Bundle outState) { if (map != null) { outState.putParcelable(KEY_CAMERA_POSITION, map.getCameraPosition()); outState.putParcelable(KEY_LOCATION, lastKnownLocation); } super.onSaveInstanceState(outState); }
Kotlin
override fun onSaveInstanceState(outState: Bundle) { map?.let { map -> outState.putParcelable(KEY_CAMERA_POSITION, map.cameraPosition) outState.putParcelable(KEY_LOCATION, lastKnownLocation) } super.onSaveInstanceState(outState) }
Rufen Sie in der
onCreate()-Methode Ihrer Aktivität den Standort des Geräts und die Kameraposition der Karte ab, falls sie zuvor gespeichert wurden:Java
// Retrieve location and camera position from saved instance state. if (savedInstanceState != null) { lastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION); cameraPosition = savedInstanceState.getParcelable(KEY_CAMERA_POSITION); }
Kotlin
if (savedInstanceState != null) { lastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION) cameraPosition = savedInstanceState.getParcelable(KEY_CAMERA_POSITION) }