1 page.title=Getting the Last Known Location 2 trainingnavtop=true 3 @jd:body 4 5 <div id="tb-wrapper"> 6 <div id="tb"> 7 8 <h2>This lesson teaches you how to</h2> 9 <ol> 10 <li><a href="#setup">Set Up Google Play Services</a></li> 11 <li><a href="#permissions">Specify App Permissions</a></li> 12 <li><a href="#play-services">Connect to Google Play Services</a></li> 13 <li><a href="#last-known">Get the Last Known Location</a></li> 14 </ol> 15 16 <h2>You should also read</h2> 17 <ul> 18 <li> 19 <a href="{@docRoot}google/play-services/setup.html">Setting up Google Play 20 Services</a> 21 </li> 22 </ul> 23 24 <h2>Try it out</h2> 25 <ul> 26 <li> 27 <a href="https://github.com/googlesamples/android-play-location/tree/master/BasicLocationSample" class="external-link">BasicLocationSample</a> 28 </li> 29 </ul> 30 </div> 31 </div> 32 33 <p>Using the Google Play services location APIs, your app can request the last 34 known location of the user's device. In most cases, you are interested in the 35 user's current location, which is usually equivalent to the last known 36 location of the device.</p> 37 38 <p>Specifically, use the 39 <a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html">fused 40 location provider</a> to retrieve the device's last known location. The fused 41 location provider is one of the location APIs in Google Play services. It 42 manages the underlying location technology and provides a simple API so that 43 you can specify requirements at a high level, like high accuracy or low power. 44 It also optimizes the device's use of battery power.</p> 45 46 <p>This lesson shows you how to make a single request for the location of a 47 device using the 48 <a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a> 49 method in the fused location provider. 50 51 <h2 id="setup">Set Up Google Play Services</h2> 52 53 <p>To access the fused location provider, your app's development project must 54 include Google Play services. Download and install the Google Play services 55 component via the <a href="{@docRoot}tools/help/sdk-manager.html">SDK 56 Manager</a> and add the library to your project. For details, see the guide to 57 <a href="{@docRoot}google/play-services/setup.html">Setting Up Google Play 58 Services</a>.</p> 59 60 <h2 id="permissions">Specify App Permissions</h2> 61 62 <p>Apps that use location services must request location permissions. Android 63 offers two location permissions: 64 {@link android.Manifest.permission#ACCESS_COARSE_LOCATION ACCESS_COARSE_LOCATION} 65 and 66 {@link android.Manifest.permission#ACCESS_FINE_LOCATION ACCESS_FINE_LOCATION}. 67 The permission you choose determines the accuracy of the location returned by 68 the API. If you specify 69 {@link android.Manifest.permission#ACCESS_COARSE_LOCATION ACCESS_COARSE_LOCATION}, 70 the API returns a location with an accuracy approximately equivalent to a city 71 block.</p> 72 73 <p>This lesson requires only coarse location. Request this permission with the 74 {@code uses-permission} element in your app manifest, as shown in the 75 following example: 76 77 <pre> 78 <manifest xmlns:android="http://schemas.android.com/apk/res/android" 79 package="com.google.android.gms.location.sample.basiclocationsample" > 80 81 <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/> 82 </manifest> 83 </pre> 84 85 <h2 id="play-services">Connect to Google Play Services</h2> 86 87 <p>To connect to the API, you need to create an instance of the 88 Google Play services API client. For details about using the client, see 89 the guide to 90 <a href="{@docRoot}google/auth/api-client.html#Starting">Accessing Google 91 APIs</a>. 92 </p> 93 94 <p>In your activity's {@link android.app.Activity#onCreate onCreate()} method, 95 create an instance of Google API Client using 96 <a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.Builder.html">{@code GoogleApiClient.Builder}</a>. 97 Use the builder to add the 98 <a href="{@docRoot}reference/com/google/android/gms/location/LocationServices.html">{@code LocationServices}</a> 99 API.</p> 100 101 <p>The sample app defines a {@code buildGoogleApiClient()} method, called from 102 the activity's {@link android.app.Activity#onCreate onCreate()} method, 103 which includes the following code.</p> 104 105 <pre> 106 protected synchronized void buildGoogleApiClient() { 107 mGoogleApiClient = new GoogleApiClient.Builder(this) 108 .addConnectionCallbacks(this) 109 .addOnConnectionFailedListener(this) 110 .addApi(LocationServices.API) 111 .build(); 112 } 113 </pre> 114 115 <h2 id="last-known">Get the Last Known Location</h2> 116 117 <p>Once you have connected to Google Play services and the location services 118 API, you can get the last known location of a user's device. When your app is 119 connected to these you can use the fused location provider's 120 <a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a> 121 method to retrieve the device location. The precision of the location returned 122 by this call is determined by the permission setting you put in your app 123 manifest, as described in the <a href="#permissions">Specify App 124 Permissions</a> section of this document.</p> 125 126 <p>To request the last known location, call the 127 <a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a> 128 method, passing it your instance of the 129 <a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.html">{@code GoogleApiClient}</a> 130 object. Do this in the 131 <a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.ConnectionCallbacks.html#onConnected(android.os.Bundle)">{@code onConnected()}</a> 132 callback provided by Google API Client, which is called when the client is 133 ready. The following code sample illustrates the request and a simple 134 handling of the response:</p> 135 136 <pre> 137 public class MainActivity extends ActionBarActivity implements 138 ConnectionCallbacks, OnConnectionFailedListener { 139 ... 140 @Override 141 public void onConnected(Bundle connectionHint) { 142 mLastLocation = LocationServices.FusedLocationApi.getLastLocation( 143 mGoogleApiClient); 144 if (mLastLocation != null) { 145 mLatitudeText.setText(String.valueOf(mLastLocation.getLatitude())); 146 mLongitudeText.setText(String.valueOf(mLastLocation.getLongitude())); 147 } 148 } 149 } 150 </pre> 151 152 <p>The 153 <a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a> 154 method returns a 155 <a href="{@docRoot}reference/android/location/Location.html">{@code Location}</a> 156 object from which you can retrieve the latitude and longitude coordinates of a 157 geographic location. The location object returned may be null in rare cases 158 when the location is not available.</p> 159 160 <p>The next lesson, 161 <a href="receive-location-updates.html">Receiving Location Updates</a>, shows 162 you how to receive periodic location updates.</p> 163
