Merge "docs: Updates lesson 1 of location API training: Get last-known location." into lmp-docs (a158abe4) · Commits · e / os / android_frameworks_base

docs/html/training/location/index.jd

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		<h2>Lessons</h2>
		<dl>
		<dt>
		<b><a href="retrieve-current.html">Retrieving the Current Location</a></b>
		<b><a href="retrieve-current.html">Getting the Last Known Location</a></b>
		</dt> <dd>
		Learn how to retrieve the user's current location.
		Learn how to retrieve the last known location of an Android device, which
		is usually equivalent to the user's current location.
		</dd> <dt>
		<b><a href="receive-location-updates.html">Receiving Location
		Updates</a></b>

docs/html/training/location/retrieve-current.jd

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		page.title=Retrieving the Current Location
		page.title=Getting the Last Known Location
		trainingnavtop=true
		@jd:body

		<div id="tb-wrapper">
		<div id="tb">

		<h2>This lesson teaches you to</h2>
		<h2>This lesson teaches you how to</h2>
		<ol>
		<li><a href="#AppPermissions">Specify App Permissions</a></li>
		<li><a href="#CheckServices">Check for Google Play services</a></li>
		<li><a href="#DefineCallbacks">Define Location Services Callbacks</a></li>
		<li><a href="#ConnectClient">Connect the Location Client</a></li>
		<li><a href="#GetLocation">Get the Current Location</a></li>
		<li><a href="#setup">Set Up Google Play Services</a></li>
		<li><a href="#permissions">Specify App Permissions</a></li>
		<li><a href="#play-services">Connect to Google Play Services</a></li>
		<li><a href="#last-known">Get the Last Known Location</a></li>
		</ol>

		<h2>You should also read</h2>
		<ul>
		<li>
		<a href="{@docRoot}google/play-services/setup.html">Setup Google Play Services SDK</a>
		<a href="{@docRoot}google/play-services/setup.html">Setting up Google Play
		Services</a>
		</li>
		</ul>

		<h2>Try it out</h2>

		<div class="download-box">
		<a href="http://developer.android.com/shareables/training/LocationUpdates.zip" class="button">Download the sample</a>
		<p class="filename">LocationUpdates.zip</p>
		</div>

		<ul>
		<li>
		<a href="https://github.com/googlesamples/android-play-location/tree/master/BasicLocationSample" class="external-link">BasicLocationSample</a>
		</li>
		</ul>
		</div>
		</div>

		<p>
		Location Services automatically maintains the user's current location, so all your app has to do
		is retrieve it as needed. The location's accuracy is based on the location permissions you've
		requested and location sensors that are currently active for the device.
		<p>
		Location Services sends the current location to your app through a location client, which is
		an instance of the Location Services class
		<code><a href="{@docRoot}reference/com/google/android/gms/location/LocationClient.html">LocationClient</a></code>.
		All requests for location information go through this client.
		</p>
		<p class="note">
		<strong>Note:</strong> Before you start the lesson, be sure that your development environment
		and test device are set up correctly. To learn more about this, read the
		<a href="{@docRoot}google/play-services/setup.html">Setup</a> section in the Google Play
		services guide.
		</p>
		<!--
		Specify App Permissions
		-->
		<h2 id="AppPermissions">Specify App Permissions</h2>
		<p>
		Apps that use Location Services must request location permissions. Android has two location
		permissions: {@link android.Manifest.permission#ACCESS_COARSE_LOCATION ACCESS_COARSE_LOCATION}
		and {@link android.Manifest.permission#ACCESS_FINE_LOCATION ACCESS_FINE_LOCATION}. The
		permission you choose controls the accuracy of the current location. If you request only coarse
		location permission, Location Services obfuscates the returned location to an accuracy
		that's roughly equivalent to a city block.
		</p>
		<p>
		Requesting {@link android.Manifest.permission#ACCESS_FINE_LOCATION ACCESS_FINE_LOCATION} implies
		a request for {@link android.Manifest.permission#ACCESS_COARSE_LOCATION ACCESS_COARSE_LOCATION}.
		</p>
		<p>
		For example, to add {@link android.Manifest.permission#ACCESS_COARSE_LOCATION
		ACCESS_COARSE_LOCATION}, insert the following as a child element of the
		<code><a href="{@docRoot}guide/topics/manifest/manifest-element.html"><manifest></a></code>
		element:
		</p>
		<p>Using the Google Play services location APIs, your app can request the last
		known location of the user's device. In most cases, you are interested in the
		user's current location, which is usually equivalent to the last known
		location of the device.</p>

		<p>Specifically, use the
		<a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html">fused
		location provider</a> to retrieve the device's last known location. The fused
		location provider is one of the location APIs in Google Play services. It
		manages the underlying location technology and provides a simple API so that
		you can specify requirements at a high level, like high accuracy or low power.
		It also optimizes the device's use of battery power.</p>

		<p>This lesson shows you how to make a single request for the location of a
		device using the
		<a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a>
		method in the fused location provider.

		<h2 id="setup">Set Up Google Play Services</h2>

		<p>To access the fused location provider, your app's development project must
		include Google Play services. Download and install the Google Play services
		component via the <a href="{@docRoot}tools/help/sdk-manager.html">SDK
		Manager</a> and add the library to your project. For details, see the guide to
		<a href="{@docRoot}google/play-services/setup.html">Setting Up Google Play
		Services</a>.</p>

		<h2 id="permissions">Specify App Permissions</h2>

		<p>Apps that use location services must request location permissions. Android
		offers two location permissions:
		{@link android.Manifest.permission#ACCESS_COARSE_LOCATION ACCESS_COARSE_LOCATION}
		and
		{@link android.Manifest.permission#ACCESS_FINE_LOCATION ACCESS_FINE_LOCATION}.
		The permission you choose determines the accuracy of the location returned by
		the API. If you specify
		{@link android.Manifest.permission#ACCESS_COARSE_LOCATION ACCESS_COARSE_LOCATION},
		the API returns a location with an accuracy approximately equivalent to a city
		block.</p>

		<p>This lesson requires only coarse location. Request this permission with the
		{@code uses-permission} element in your app manifest, as shown in the
		following example:

		<pre>
		<manifest xmlns:android="http://schemas.android.com/apk/res/android"
		package="com.google.android.gms.location.sample.basiclocationsample" >

		<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
		</manifest>
		</pre>
		<!--
		Check for Google Play Services
		-->
		<h2 id="CheckServices">Check for Google Play Services</h2>
		<p>
		Location Services is part of the Google Play services APK. Since it's hard to anticipate the
		state of the user's device, you should always check that the APK is installed before you attempt
		to connect to Location Services. To check that the APK is installed, call
		<code><a href="{@docRoot}reference/com/google/android/gms/common/GooglePlayServicesUtil.html#isGooglePlayServicesAvailable(android.content.Context)">GooglePlayServicesUtil.isGooglePlayServicesAvailable()</a></code>,
		which returns one of the
		integer result codes listed in the reference documentation for
		<code><a href="{@docRoot}reference/com/google/android/gms/common/ConnectionResult.html">ConnectionResult</a></code>.
		If you encounter an error, call
		<code><a href="{@docRoot}reference/com/google/android/gms/common/GooglePlayServicesUtil.html#getErrorDialog(int, android.app.Activity, int)">GooglePlayServicesUtil.getErrorDialog()</a></code>
		to retrieve localized dialog that prompts users to take the correct action, then display
		the dialog in a {@link android.support.v4.app.DialogFragment}. The dialog may allow the
		user to correct the problem, in which case Google Play services may send a result back to your
		activity. To handle this result, override the method
		{@link android.support.v4.app.FragmentActivity#onActivityResult onActivityResult()}.
		</p>
		<p>
		Since you usually need to check for Google Play services in more than one place in your code,
		define a method that encapsulates the check, then call the method before each connection
		attempt. The following snippet contains all of the code required to check for Google
		Play services:
		</p>
		<pre>
		public class MainActivity extends FragmentActivity {
		...
		// Global constants
		/*
		* Define a request code to send to Google Play services
		* This code is returned in Activity.onActivityResult
		*/
		private final static int
		CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;
		...
		// Define a DialogFragment that displays the error dialog
		public static class ErrorDialogFragment extends DialogFragment {
		// Global field to contain the error dialog
		private Dialog mDialog;
		// Default constructor. Sets the dialog field to null
		public ErrorDialogFragment() {
		super();
		mDialog = null;
		}
		// Set the dialog to display
		public void setDialog(Dialog dialog) {
		mDialog = dialog;
		}
		// Return a Dialog to the DialogFragment.
		@Override
		public Dialog onCreateDialog(Bundle savedInstanceState) {
		return mDialog;
		}
		}
		...
		/*
		* Handle results returned to the FragmentActivity
		* by Google Play services
		*/
		@Override
		protected void onActivityResult(
		int requestCode, int resultCode, Intent data) {
		// Decide what to do based on the original request code
		switch (requestCode) {
		...
		case CONNECTION_FAILURE_RESOLUTION_REQUEST :
		/*
		* If the result code is Activity.RESULT_OK, try
		* to connect again
		*/
		switch (resultCode) {
		case Activity.RESULT_OK :
		/*
		* Try the request again
		*/
		...
		break;
		}
		...
		}
		}
		...
		private boolean servicesConnected() {
		// Check that Google Play services is available
		int resultCode =
		GooglePlayServicesUtil.
		isGooglePlayServicesAvailable(this);
		// If Google Play services is available
		if (ConnectionResult.SUCCESS == resultCode) {
		// In debug mode, log the status
		Log.d("Location Updates",
		"Google Play services is available.");
		// Continue
		return true;
		// Google Play services was not available for some reason.
		// resultCode holds the error code.
		} else {
		// Get the error dialog from Google Play services
		Dialog errorDialog = GooglePlayServicesUtil.getErrorDialog(
		resultCode,
		this,
		CONNECTION_FAILURE_RESOLUTION_REQUEST);

		// If Google Play services can provide an error dialog
		if (errorDialog != null) {
		// Create a new DialogFragment for the error dialog
		ErrorDialogFragment errorFragment =
		new ErrorDialogFragment();
		// Set the dialog in the DialogFragment
		errorFragment.setDialog(errorDialog);
		// Show the error dialog in the DialogFragment
		errorFragment.show(getSupportFragmentManager(),
		"Location Updates");
		}
		}
		}
		...
		}
		</pre>
		<p>
		Snippets in the following sections call this method to verify that Google Play services is
		available.
		</p>
		<!--
		Define Location Services Callbacks
		-->
		<h2 id="DefineCallbacks">Define Location Services Callbacks</h2>
		<p>
		To get the current location, create a location client, connect it
		to Location Services, and then call its
		<code><a href="{@docRoot}reference/com/google/android/gms/location/LocationClient.html#getLastLocation()">getLastLocation()</a></code>
		method. The return value is the best, most recent location, based on the permissions your
		app requested and the currently-enabled location sensors.
		<p>
		<p>
		Before you create the location client, implement the interfaces that Location Services uses to
		communicate with your app:
		</p>
		<dl>
		<dt>
		<code><a href="{@docRoot}reference/com/google/android/gms/common/GooglePlayServicesClient.ConnectionCallbacks.html">ConnectionCallbacks</a></code>
		</dt>
		<dd>
		Specifies methods that Location Services calls when a location client is connected or
		disconnected.
		</dd>
		<dt>
		<code><a href="{@docRoot}reference/com/google/android/gms/common/GooglePlayServicesClient.OnConnectionFailedListener.html">OnConnectionFailedListener</a></code>
		</dt>
		<dd>
		Specifies a method that Location Services calls if an error occurs while attempting to
		connect the location client. This method uses the previously-defined {@code showErrorDialog}
		method to display an error dialog that attempts to fix the problem using Google Play
		services.
		</dd>
		</dl>
		<p>
		The following snippet shows how to specify the interfaces and define the methods:
		<h2 id="play-services">Connect to Google Play Services</h2>

		<p>To connect to the API, you need to create an instance of the
		Google Play services API client. For details about using the client, see
		the guide to
		<a href="{@docRoot}google/auth/api-client.html#Starting">Accessing Google
		APIs</a>.
		</p>
		<pre>
		public class MainActivity extends FragmentActivity implements
		GooglePlayServicesClient.ConnectionCallbacks,
		GooglePlayServicesClient.OnConnectionFailedListener {
		...
		/*
		* Called by Location Services when the request to connect the
		* client finishes successfully. At this point, you can
		* request the current location or start periodic updates
		*/
		@Override
		public void onConnected(Bundle dataBundle) {
		// Display the connection status
		Toast.makeText(this, "Connected", Toast.LENGTH_SHORT).show();

		}
		...
		/*
		* Called by Location Services if the connection to the
		* location client drops because of an error.
		*/
		@Override
		public void onDisconnected() {
		// Display the connection status
		Toast.makeText(this, "Disconnected. Please re-connect.",
		Toast.LENGTH_SHORT).show();
		}
		...
		/*
		* Called by Location Services if the attempt to
		* Location Services fails.
		*/
		@Override
		public void onConnectionFailed(ConnectionResult connectionResult) {
		/*
		* Google Play services can resolve some errors it detects.
		* If the error has a resolution, try sending an Intent to
		* start a Google Play services activity that can resolve
		* error.
		*/
		if (connectionResult.hasResolution()) {
		try {
		// Start an Activity that tries to resolve the error
		connectionResult.startResolutionForResult(
		this,
		CONNECTION_FAILURE_RESOLUTION_REQUEST);
		/*
		* Thrown if Google Play services canceled the original
		* PendingIntent
		*/
		} catch (IntentSender.SendIntentException e) {
		// Log the error
		e.printStackTrace();
		}
		} else {
		/*
		* If no resolution is available, display a dialog to the
		* user with the error.
		*/
		showErrorDialog(connectionResult.getErrorCode());
		}
		}
		...
		<p>In your activity's {@link android.app.Activity#onCreate onCreate()} method,
		create an instance of Google API Client using
		<a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.Builder.html">{@code GoogleApiClient.Builder}</a>.
		Use the builder to add the
		<a href="{@docRoot}reference/com/google/android/gms/location/LocationServices.html">{@code LocationServices}</a>
		API.</p>

		<p>The sample app defines a {@code buildGoogleApiClient()} method, called from
		the activity's {@link android.app.Activity#onCreate onCreate()} method,
		which includes the following code.</p>

		<pre>
		protected synchronized void buildGoogleApiClient() {
		mGoogleApiClient = new GoogleApiClient.Builder(this)
		.addConnectionCallbacks(this)
		.addOnConnectionFailedListener(this)
		.addApi(LocationServices.API)
		.build();
		}
		</pre>
		<!--
		Connect the Location Client
		-->
		<h2 id="ConnectClient">Connect the Location Client</h2>
		<p>
		Now that the callback methods are in place, create the location client and connect it to
		Location Services.
		</p>
		<p>
		You should create the location client in {@link android.support.v4.app.FragmentActivity#onCreate
		onCreate()}, then connect it in
		{@link android.support.v4.app.FragmentActivity#onStart onStart()}, so that Location Services
		maintains the current location while your activity is fully visible. Disconnect the client in
		{@link android.support.v4.app.FragmentActivity#onStop onStop()}, so that when your app is not
		visible, Location Services is not maintaining the current location. Following this pattern of
		connection and disconnection helps save battery power. For example:
		</p>
		<p class="note">
		<strong>Note:</strong> The current location is only maintained while a location client is
		connected to Location Service. Assuming that no other apps are connected to Location Services,
		if you disconnect the client and then sometime later call
		<code><a href="{@docRoot}reference/com/google/android/gms/location/LocationClient.html#getLastLocation()">getLastLocation()</a></code>,
		the result may be out of date.
		</p>

		<h2 id="last-known">Get the Last Known Location</h2>

		<p>Once you have connected to Google Play services and the location services
		API, you can get the last known location of a user's device. When your app is
		connected to these you can use the fused location provider's
		<a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a>
		method to retrieve the device location. The precision of the location returned
		by this call is determined by the permission setting you put in your app
		manifest, as described in the <a href="#permissions">Specify App
		Permissions</a> section of this document.</p>

		<p>To request the last known location, call the
		<a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a>
		method, passing it your instance of the
		<a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.html">{@code GoogleApiClient}</a>
		object. Do this in the
		<a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.ConnectionCallbacks.html#onConnected(android.os.Bundle)">{@code onConnected()}</a>
		callback provided by Google API Client, which is called when the client is
		ready. The following code sample illustrates the request and a simple
		handling of the response:</p>

		<pre>
		public class MainActivity extends FragmentActivity implements
		GooglePlayServicesClient.ConnectionCallbacks,
		GooglePlayServicesClient.OnConnectionFailedListener {
		...
		@Override
		protected void onCreate(Bundle savedInstanceState) {
		...
		/*
		* Create a new location client, using the enclosing class to
		* handle callbacks.
		*/
		mLocationClient = new LocationClient(this, this, this);
		...
		}
		...
		/*
		* Called when the Activity becomes visible.
		*/
		@Override
		protected void onStart() {
		super.onStart();
		// Connect the client.
		mLocationClient.connect();
		}
		public class MainActivity extends ActionBarActivity implements
		ConnectionCallbacks, OnConnectionFailedListener {
		...
		/*
		* Called when the Activity is no longer visible.
		*/
		@Override
		protected void onStop() {
		// Disconnecting the client invalidates it.
		mLocationClient.disconnect();
		super.onStop();
		public void onConnected(Bundle connectionHint) {
		mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
		mGoogleApiClient);
		if (mLastLocation != null) {
		mLatitudeText.setText(String.valueOf(mLastLocation.getLatitude()));
		mLongitudeText.setText(String.valueOf(mLastLocation.getLongitude()));
		}
		...
		}
		</pre>
		<!--
		Get the Current Location
		-->
		<h2 id="GetLocation">Get the Current Location</h2>
		<p>
		To get the current location, call
		<code><a href="{@docRoot}reference/com/google/android/gms/location/LocationClient.html#getLastLocation()">getLastLocation()</a></code>.
		For example:
		</p>
		<pre>
		public class MainActivity extends FragmentActivity implements
		GooglePlayServicesClient.ConnectionCallbacks,
		GooglePlayServicesClient.OnConnectionFailedListener {
		...
		// Global variable to hold the current location
		Location mCurrentLocation;
		...
		mCurrentLocation = mLocationClient.getLastLocation();
		...
		}
		</pre>
		<p>
		The next lesson, <a href="receive-location-updates.html">Receiving Location Updates</a>, shows
		you how to receive periodic location updates from Location Services.
		</p>

		<p>The
		<a href="{@docRoot}reference/com/google/android/gms/location/FusedLocationProviderApi.html#getLastLocation(com.google.android.gms.common.api.GoogleApiClient)">{@code getLastLocation()}</a>
		method returns a
		<a href="{@docRoot}reference/android/location/Location.html">{@code Location}</a>
		object from which you can retrieve the latitude and longitude coordinates of a
		geographic location. The location object returned may be null in rare cases
		when the location is not available.</p>

		<p>The next lesson,
		<a href="receive-location-updates.html">Receiving Location Updates</a>, shows
		you how to receive periodic location updates.</p>

docs/html/training/training_toc.cs

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		@@ -694,7 +694,7 @@ include the action bar on devices running Android 2.1 or higher."
		<ul>
		<li>
		<a href="<?cs var:toroot ?>training/location/retrieve-current.html">
		Retrieving the Current Location
		Getting the Last Known Location
		</a>
		</li>
		<li>