Untuk mendapatkan lokasi perangkat, pada dasarnya ada tiga cara. Pertama, adalah menggunakan GPS. Saat ini, hampir semua perangkat mobile pasti dilengkapi denga GPS. Karena ada banyak sekali satelit yang mengorbit bumi, maka kita bisa menggunakan penerima GPS yang sudah ada di dalam perangkat kita untuk menemukan lokasi kita dengan mudah. Sayangnya, GPS hanya bisa berjalan apabila tidak ada halangan, misalnya perlu langit yang cerah, tidak bisa menembus tembok-tembok indoor, terowongan, dll.
Kedua, cara lain yang efektif adalah dengan melacak lokasi melalui menara BTS. Ketika handphone aktif, handphone akan selalu terus menerus terkoneksi dengan BTS. Dengan mengetahui identitas BTS maka semua informasi lokasi fisik bisa dilacak dengan memanfaatkan berbagai macam database tentang menara BTS dan menemukan lokasi geografi perangkat kita. Kelebihan memanfaatkan menara BTS adalah bisa menembus lokasi-lokasi indoor tanpa perlu mendapatkan informasi dari satelit. Tetapi tingkat akurasinya masih lebih rendah dibanding dengan GPS karena akurasinya bergantung pada sinyal yang saling tumpang tindih dan sehingga menghasilkan informasi yang sedikit berbeda-beda. Menara BTS akan sangat baik di area-are yang padat penduduk karena lokasi BTS akan lebih dekat.
Ketiga, adalah menggunaan pelacakan berdasarkan Wi-Fi. Dibadingkan dengan terkoneksi dengan menara BTS, perangkat akan terkoneksi dengan jaringan Wi-Fi dan men-cek provider layanannya dengan berbagai macam database untuk menentukan lokasi yang sedang dilayani oleh provider tersebut. Dari ketiga macam cara tersebut, Wi-Fi adalah cara yang paling tidak akurat.
Latihan ini akan menjelaskan bagaimana menemukan lokasi saat ini pada perangkat Android dan menampilkan marker di map/peta untuk lokasi terdekat.
1. Kode file java: 'MapsActivityCurrentPlaces.java':
package com.example.currentplacedetailsonmap;
import android.content.pm.PackageManager;
import android.location.Location;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.TextView;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.api.PendingResult;
import com.google.android.gms.common.api.ResultCallback;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.location.places.PlaceLikelihood;
import com.google.android.gms.location.places.PlaceLikelihoodBuffer;
import com.google.android.gms.location.places.Places;
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;
/**
* An activity that displays a map showing places around the device's current location.
*/
public class MapsActivityCurrentPlaces extends AppCompatActivity implements
OnMapReadyCallback,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
private static final String TAG = MapsActivityCurrentPlaces.class.getSimpleName();
private GoogleMap mMap;
private CameraPosition mCameraPosition;
/* The entry point to Google Play services, used by the Places API and Fused Location Provider.*/
private GoogleApiClient mGoogleApiClient;
// A request object to store parameters for requests to the FusedLocationProviderApi.
private LocationRequest mLocationRequest;
/* The desired interval for location updates. Inexact. Updates may be more or less frequent.*/
private static final long UPDATE_INTERVAL_IN_MILLISECONDS = 10000;
/* The fastest rate for active location updates. Exact. Updates will never be more frequent than this value. */
private static final long FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS =
UPDATE_INTERVAL_IN_MILLISECONDS / 2;
/* A default location (Sydney, Australia) and default zoom to use when location permission is not granted. */
private final LatLng mDefaultLocation = 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 mLocationPermissionGranted;
// The geographical location where the device is currently located.
private Location mCurrentLocation;
// Keys for storing activity state.
private static final String KEY_CAMERA_POSITION = "camera_position";
private static final String KEY_LOCATION = "location";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Retrieve location and camera position from saved instance state.
if (savedInstanceState != null) {
mCurrentLocation = savedInstanceState.getParcelable(KEY_LOCATION);
mCameraPosition = savedInstanceState.getParcelable(KEY_CAMERA_POSITION);
}
// Retrieve the content view that renders the map.
setContentView(R.layout.activity_maps);
/* Build the Play services client for use by the Fused Location Provider and the Places API. */
buildGoogleApiClient();
mGoogleApiClient.connect();
}
/**
* Get the device location and nearby places when the activity is restored after a pause.
*/
@Override
protected void onResume() {
super.onResume();
if (mGoogleApiClient.isConnected()) {
getDeviceLocation();
}
updateMarkers();
}
/**
* Stop location updates when the activity is no longer in focus, to reduce battery consumption.
*/
@Override
protected void onPause() {
super.onPause();
if (mGoogleApiClient.isConnected()) {
LocationServices.FusedLocationApi.removeLocationUpdates(
mGoogleApiClient, this);
}
}
/**
* Saves the state of the map when the activity is paused.
*/
@Override
protected void onSaveInstanceState(Bundle outState) {
if (mMap != null) {
outState.putParcelable(KEY_CAMERA_POSITION, mMap.getCameraPosition());
outState.putParcelable(KEY_LOCATION, mCurrentLocation);
super.onSaveInstanceState(outState);
}
}
/**
* Gets the device's current location and builds the map
* when the Google Play services client is successfully connected.
*/
@Override
public void onConnected(Bundle connectionHint) {
getDeviceLocation();
// Build the map.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
/**
* Handles failure to connect to the Google Play services client.
*/
@Override
public void onConnectionFailed(@NonNull ConnectionResult result) {
// Refer to the reference doc for ConnectionResult to see what error codes might
// be returned in onConnectionFailed.
Log.d(TAG, "Play services connection failed: ConnectionResult.getErrorCode() = "
+ result.getErrorCode());
}
/**
* Handles suspension of the connection to the Google Play services client.
*/
@Override
public void onConnectionSuspended(int cause) {
Log.d(TAG, "Play services connection suspended");
}
/**
* Handles the callback when location changes.
*/
@Override
public void onLocationChanged(Location location) {
mCurrentLocation = location;
updateMarkers();
}
/**
* 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) {
mMap = map;
// Turn on the My Location layer and the related control on the map.
updateLocationUI();
// Add markers for nearby places.
updateMarkers();
// Use a custom info window adapter to handle multiple lines of text in the
// info window contents.
mMap.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, null);
TextView title = ((TextView) infoWindow.findViewById(R.id.title));
title.setText(marker.getTitle());
TextView snippet = ((TextView) infoWindow.findViewById(R.id.snippet));
snippet.setText(marker.getSnippet());
return infoWindow;
}
});
/*
* Set the map's camera position to the current location of the device.
* If the previous state was saved, set the position to the saved state.
* If the current location is unknown, use a default position and zoom value.
*/
if (mCameraPosition != null) {
mMap.moveCamera(CameraUpdateFactory.newCameraPosition(mCameraPosition));
} else if (mCurrentLocation != null) {
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(
new LatLng(mCurrentLocation.getLatitude(),
mCurrentLocation.getLongitude()), DEFAULT_ZOOM));
} else {
Log.d(TAG, "Current location is null. Using defaults.");
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(mDefaultLocation, DEFAULT_ZOOM));
mMap.getUiSettings().setMyLocationButtonEnabled(false);
}
}
/**
* Builds a GoogleApiClient.
* Uses the addApi() method to request the Google Places API and the Fused Location Provider.
*/
private synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.enableAutoManage(this /* FragmentActivity */,
this /* OnConnectionFailedListener */)
.addConnectionCallbacks(this)
.addApi(LocationServices.API)
.addApi(Places.GEO_DATA_API)
.addApi(Places.PLACE_DETECTION_API)
.build();
createLocationRequest();
}
/**
* Sets up the location request.
*/
private void createLocationRequest() {
mLocationRequest = new LocationRequest();
/*
* Sets the desired interval for active location updates. This interval is
* inexact. You may not receive updates at all if no location sources are available, or
* you may receive them slower than requested. You may also receive updates faster than
* requested if other applications are requesting location at a faster interval.
*/
mLocationRequest.setInterval(UPDATE_INTERVAL_IN_MILLISECONDS);
/*
* Sets the fastest rate for active location updates. This interval is exact, and your
* application will never receive updates faster than this value.
*/
mLocationRequest.setFastestInterval(FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS);
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}
/**
* Gets the current location of the device and starts the location update notifications.
*/
private void getDeviceLocation() {
/*
* 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) {
mLocationPermissionGranted = true;
} else {
ActivityCompat.requestPermissions(this,
new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION},
PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION);
}
/*
* Get the best and most recent location of the device, which may be null in rare
* cases when a location is not available.
* Also request regular updates about the device location.
*/
if (mLocationPermissionGranted) {
mCurrentLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient,
mLocationRequest, this);
}
}
/**
* Handles the result of the request for location permissions.
*/
@Override
public void onRequestPermissionsResult(int requestCode,
@NonNull String permissions[],
@NonNull int[] grantResults) {
mLocationPermissionGranted = false;
switch (requestCode) {
case PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
mLocationPermissionGranted = true;
}
}
}
updateLocationUI();
}
/**
* Adds markers for places nearby the device and turns the My Location feature on or off,
* provided location permission has been granted.
*/
private void updateMarkers() {
if (mMap == null) {
return;
}
if (mLocationPermissionGranted) {
// Get the businesses and other points of interest located
// nearest to the device's current location.
@SuppressWarnings("MissingPermission")
PendingResultresult = Places.PlaceDetectionApi
.getCurrentPlace(mGoogleApiClient, null);
result.setResultCallback(new ResultCallback() {
@Override
public void onResult(@NonNull PlaceLikelihoodBuffer likelyPlaces) {
for (PlaceLikelihood placeLikelihood : likelyPlaces) {
// Add a marker for each place near the device's current location, with an
// info window showing place information.
String attributions = (String) placeLikelihood.getPlace().getAttributions();
String snippet = (String) placeLikelihood.getPlace().getAddress();
if (attributions != null) {
snippet = snippet + "\n" + attributions;
}
mMap.addMarker(new MarkerOptions()
.position(placeLikelihood.getPlace().getLatLng())
.title((String) placeLikelihood.getPlace().getName())
.snippet(snippet));
}
// Release the place likelihood buffer.
likelyPlaces.release();
}
});
} else {
mMap.addMarker(new MarkerOptions()
.position(mDefaultLocation)
.title(getString(R.string.default_info_title))
.snippet(getString(R.string.default_info_snippet)));
}
}
/**
* Updates the map's UI settings based on whether the user has granted location permission.
*/
@SuppressWarnings("MissingPermission")
private void updateLocationUI() {
if (mMap == null) {
return;
}
if (mLocationPermissionGranted) {
mMap.setMyLocationEnabled(true);
mMap.getUiSettings().setMyLocationButtonEnabled(true);
} else {
mMap.setMyLocationEnabled(false);
mMap.getUiSettings().setMyLocationButtonEnabled(false);
mCurrentLocation = null;
}
}
}
2. File 'AndroidManifest.xml':
<?xml version="1.0" encoding="utf-8"?>3. File layout xml: 'activity_maps.xml':
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.currentplacedetailsonmap">
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
<!--
The API key for Google Maps-based APIs.
-->
<meta-data
android:name="com.google.android.geo.API_KEY"
android:value="AIzaSyCveYF1KRo72Di3is65ayP3e0xjCPmqsiw" />
<activity
android:name="com.example.currentplacedetailsonmap.MapsActivityCurrentPlaces"
android:label="@string/title_activity_maps">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"4. File layout xml: 'custom_info_contents.xml':
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.MapsActivityCurrentPlaces" />
<?xml version="1.0" encoding="utf-8"?>
<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>
Penjelasan seluruh kode di atas akan dibahas dalam post berikutnya atau di post ini: Penjelasan Kode Mendapatkan Lokasi Detil Perangkat Saat Ini
sumber: https://github.com/googlemaps/android-samples
License
(See each sample directory for details.)
Copyright 2015 The Android Open Source Project
Copyright 2015 Google, Inc.
Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you 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.
No comments:
Post a Comment