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 the following code 75 snippet shows: 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 the 96 <a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.Builder.html">{@code GoogleApiClient.Builder}</a> class to add the 97 <a href="{@docRoot}reference/com/google/android/gms/location/LocationServices.html"> 98 {@code LocationServices}</a> 99 API, as the following code snippet shows.</p> 100 101 <pre> 102 // Create an instance of GoogleAPIClient. 103 if (mGoogleApiClient == null) { 104 mGoogleApiClient = new GoogleApiClient.Builder(this) 105 .addConnectionCallbacks(this) 106 .addOnConnectionFailedListener(this) 107 .addApi(LocationServices.API) 108 .build(); 109 } 110 </pre> 111 112 <p>To connect, call 113 <a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient#connect()"> 114 {@code connect()}</a> 115 from the activity's 116 <a href="{@docRoot}reference/android/app/Activity.html#onStart()">{@code onStart()}</a> 117 method. To disconnect, call 118 <a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient#disconnect()"> 119 {@code disconnect()}</a> from the activity's 120 <a href="{@docRoot}reference/android/app/Activity.html#onStop()"> 121 {@code onStop()}</a> method. The following snippet shows an example of how 122 to use both of these methods. 123 </p> 124 125 <pre> 126 protected void onStart() { 127 mGoogleApiClient.connect(); 128 super.onStart(); 129 } 130 131 protected void onStop() { 132 mGoogleApiClient.disconnect(); 133 super.onStop(); 134 } 135 </pre> 136 137 <h2 id="last-known">Get the Last Known Location</h2> 138 139 <p>Once you have connected to Google Play services and the location services 140 API, you can get the last known location of a user's device. When your app is 141 connected to these you can use the fused location provider's 142 <a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a> 143 method to retrieve the device location. The precision of the location returned 144 by this call is determined by the permission setting you put in your app 145 manifest, as described in the <a href="#permissions">Specify App 146 Permissions</a> section of this document.</p> 147 148 <p>To request the last known location, call the 149 <a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a> 150 method, passing it your instance of the 151 <a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.html">{@code GoogleApiClient}</a> 152 object. Do this in the 153 <a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.ConnectionCallbacks.html#onConnected(android.os.Bundle)">{@code onConnected()}</a> 154 callback provided by Google API Client, which is called when the client is 155 ready. The following code snippet illustrates the request and a simple 156 handling of the response:</p> 157 158 <pre> 159 public class MainActivity extends ActionBarActivity implements 160 ConnectionCallbacks, OnConnectionFailedListener { 161 ... 162 @Override 163 public void onConnected(Bundle connectionHint) { 164 mLastLocation = LocationServices.FusedLocationApi.getLastLocation( 165 mGoogleApiClient); 166 if (mLastLocation != null) { 167 mLatitudeText.setText(String.valueOf(mLastLocation.getLatitude())); 168 mLongitudeText.setText(String.valueOf(mLastLocation.getLongitude())); 169 } 170 } 171 } 172 </pre> 173 174 <p>The 175 <a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a> 176 method returns a 177 <a href="{@docRoot}reference/android/location/Location.html">{@code Location}</a> 178 object from which you can retrieve the latitude and longitude coordinates of a 179 geographic location. The location object returned may be null in rare cases 180 when the location is not available.</p> 181 182 <p>The next lesson, 183 <a href="change-location-settings.html">Changing Location Settings</a>, shows 184 you how to detect the current location settings, and prompt the user to 185 change settings as appropriate for your app's requirements.</p> 186
