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Department of Information Engineering, CUHK
MScIE – 2nd Semester, 2016/17
IEMS 5722
Mobile Network Programming
and Distributed Server Architecture
Lecture 12
Advanced Android Programming
Lecturer: Albert C. M. Au Yeung
30th March, 2017
Google Play Services
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Google Play Services
• Google Play Services is a set of cloud services and APIs for Android devices
• Version 8.4 released 18 Dec, 2015
• Allows you to integrate various services from Google into the mobile app
• Some of Google’s services include
› Location detection
› Geocoding and reverse geo-coding
› Maps API (e.g. navigation, street views)
› Google drive for cloud storage
› Google Wallet for online payment
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Google Play Services
Google Services
API Requests
and Responses
Google Play
App Store
Automatic
Update
Your Mobile App
GMS Client Library
An Android Device
Google Play
Services APK
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Google Play Services
Setting up Google Play Services
• Download latest Google Play services SDK
• Update your build.gradle file
(Refer to the link below)
Reference: https://developers.google.com/android/guides/setup
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Accessing Google APIs
To access various Google APIs, you need to create an instance of GoogleApiClient
• Acts as a common entry point to all Google services
• Manages network connection between the device and each service
Reference: https://developers.google.com/android/guides/api-client
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Accessing Google
APIs
public class MyActivity extends FragmentActivity
implements OnConnectionFailedListener {
private GoogleApiClient mGoogleApiClient;
You can create an
instance of
GoogleApiClient with
connection to
specific APIs by
using a builder:
@Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
}
// Create a GoogleApiClient instance
mGoogleApiClient = new GoogleApiClient.Builder(this)
.enableAutoManage(this /* FragmentActivity */,
this /* OnConnectionFailedListener */)
.addApi(Drive.API)
.addScope(Drive.SCOPE_FILE)
.build();
// ...
@Override public void onConnectionFailed(ConnectionResult result) {
// An unresolvable error has occurred and a connection to Google
// APIs could not be established. Display an error message,
// or handle the failure silently
// ...
}
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Google APIs for Android
For a list of Google APIs for Android, see:
• https://developers.google.com/android/
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Location Detection
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Location Detection
• Location detection is one of the most commonly used features of
smartphones
• Many apps offers location-based services, e.g.:
Ø Maps, transportation and navigation
Ø Location-based social networking
Ø Tracking
Ø News
Ø Weather forecast
Ø ...
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Location Detection
• Mobile phones can detect locations by using a variety of data sources
1. GPS (Global Positioning System)
2. Information of base stations (Cell ID)
(e.g. http://opencellid.org/)
3. Wi-Fi + IP Address
4. Others
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Location Detection
• Android provides simple APIs that return user’s current location by
combining the input from different sources
Android Framework’s
Location APIs
(android.location)
Google Play Services
Location APIs
(com.google.android.gms.location)
Preferred Option
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Google Play Services Location APIs
• If your app needs to use location services, you need to request permission
from the user
• Two permissions:
1. ACCESS_COARSE_LOCATION
(accurate to the level of a city block)
2. ACCESS_FINE_LOCATION
(accurate to a few metres)
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
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Google Play Services Location APIs
• The flow of setting up the app to use the location APIs
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1
Connect to
Google Play
services
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Set up a location
request with
parameters
Request location
updates from the
API
4
5
Obtain the last
known location of
the phone
Receive location
updates
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1. Connecting to Google Play Services
• Firstly, you need to get an instance of the Google Play services API client
GoogleApiClient mGoogleApiClient;
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
}
Adding the location service
API here
NOTE: We do not enable auto-management of connection here.
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1. Connecting to Google Play Services
• Connect the API client when the activity is started, and disconnect when it is
stopped
@Override
protected void onStart() {
super.onStart();
if (mGoogleApiClient != null) {
mGoogleApiClient.connect();
}
}
@Override
protected void onStop() {
if (mGoogleApiClient != null) {
mGoogleApiClient.disconnect();
}
super.onStop();
}
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1. Connecting to Google Play Services
• To receive status updates from the API client, your activity need to
implements some interfaces and callback functions
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
public class MainActivity extends Activity implements
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
...
}
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2. Setting up a Location Request
• The Location APIs will notify your app when it has an updated information
about the location of the user
• You need to submit a request to receive location updates
Android System
Submit location
request with
parameters
Send location
updates when
there is changes
or according to a
preset frequency
Your App
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2. Setting up a Location Request
• Creating a location request:
protected void createLocationRequest() {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(10000);
mLocationRequest.setFastestInterval(5000);
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}
• Interval (ms): how frequent you would like to receive updates
• Fastest Interval (ms): the fastest rate at which your app will receive updates
• Priority: Different priority settings affect power consumption
(ref.: https://developer.android.com/training/location/receive-location-updates.html)
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3. Request Location Updates
• Once the API client is connected, you can submit your location request:
@Override
public void onConnected(Bundle connectionHint) {
...
LocationServices.FusedLocationApi.requestLocationUpdates(
mGoogleApiClient, mLocationRequest, this);
...
}
You need to pass to this method a
location listener. If your activity has
implemented the location listener
interface, you can provide the reference of
the current activity here.
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4. Obtain the Last Known Location
• Usually it takes some time before you will receive the first location update
• You can obtain the “last known location” of the user first, so that you can
start executing some functions in your app
...
@Override
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()));
}
}
...
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5. Receiving Location Updates
• Finally, set up the callback functions so that you can receive location
updates
...
@Override
public void onLocationChanged(Location location) {
mCurrentLocation = location;
mLastUpdateTime = DateFormat.getTimeInstance().format(new Date());
...
// Perform actions based on the updated location
// e.g. update the UI, alert the user, etc.
}
...
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Stop Receiving Location Updates
• To save power, you should stop requesting location updates when it is no
longer necessary. For example:
@Override
protected void onPause() {
super.onPause();
LocationServices.FusedLocationApi.removeLocationUpdates(
mGoogleApiClient, this);
}
@Override
public void onResume() {
super.onResume();
if (mGoogleApiClient.isConnected()) {
LocationServices.FusedLocationApi.requestLocationUpdates(
mGoogleApiClient, mLocationRequest, this);
}
}
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Using Google Maps
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Using Google Maps in Your App
• You can embed an interactive map in your app by using Google Maps
Android API
• Google Maps functions include:
Ø Provide interactive maps with 3D maps, satellite view, terrain view, road
maps, etc.
Ø Allow overlaying of different components, such as markers, polygons, etc.
Ø Control user’s view such as rotation, zoom, pan
Ø Street view
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Getting Started
• To embed Google Maps in your app, you need to set up your app and
obtain an API key from Google
• Follow the instructions at:
https://developers.google.com/maps/documentation/android/start
• Once you have a key, add it to your manifest file:
<meta-data
android:name="com.google.android.geo.API_KEY"
android:value="API_KEY"/>
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Adding a Map to Your App
• To add a map to your activity, add a fragment with android:name equals to
“com.google.android.gms.maps.MapFragment”:
<?xml version="1.0" encoding="utf-8"?>
<fragment
xmlns:android="http://schemas.android.com/apk/res/android"
android:name="com.google.android.gms.maps.MapFragment"
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
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Adding a Map to Your App
• To control the map, in the code of the activity, you need to obtain the map
object:
public class MainActivity extends FragmentActivity implements OnMapReadyCallback {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
MapFragment mapFragment = (MapFragment) getFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
}
@Override
public void onMapReady(GoogleMap map) {
map.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
}
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Other Maps SDKs
• Nokia HERE Map
https://developer.here.com/
• OpenStreetMap
http://www.openstreetmap.org/
• Baidu Map
http://lbsyun.baidu.com/sdk/download
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Geocoding & Reverse Geocoding
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Geocoding & Reverse Geocoding
Geocoding
• Converting an address to a geographic location (latitude/longitude)
Reverse Geocoding
• Converting a geographic location (latitude/longitude) to an address
Both of these functions can be performed by using the Geocoder class in
Android
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Reverse Geocoding
Reverse Geocoding
• In a mobile app, you might need want to let the user choose a location on
the map, and then retrieve the address of that location
(or when you need to locate the user using GPS/Wi-Fi signals)
• To use reverse geocoding, you need a precise geolocation, therefore you
should ask for the ACCESS_FINE_LOCATION permission
• You can use the Geocoder class to perform reverse geocoding
(see next page)
Reference: http://developer.android.com/training/location/display-address.html
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Reverse Geocoding
• The function getFromLocation is a blocking and may take a long time (several
seconds) to response
• You should not execute this on the UI thread
• Instead, you should use one of the following methods
› AsyncTask
› Intent service (IntentService) with result receiver (ResultReceiver) or
local broadcasting (LocalBroadcastManager)
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Geocoding
• Similarly, you can obtain a geolocation by providing a address
(i.e. geocoding)
• For example:
String address = "The Chinese University of Hong Kong, Shatin, Hong Kong";
List<Address> list = null;
try {
addresses = geocoder.getFromLocationName(address, 1);
} catch (IOException ioException) {
// Catch network or other I/O problems
} catch (IllegalArgumentException illegalArgumentException) {
// Catch invalid latitude or longitude values
}
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Other Cloud Services
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Cloud Services & APIs
• Facebook
https://developers.facebook.com/
• Instagram
https://www.instagram.com/developer/
• WeChat
https://open.weixin.qq.com/
• Baidu
http://developer.baidu.com/
• YouTube
https://www.youtube.com/yt/dev/
• IBM Developer Cloud
https://www.ibm.com/smarterplanet/us/en/ibmwatson/developercloud/
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Auto-complete Text Views
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Auto-complete Text Views
• A text view that automatically suggests words
or phrases for input while the user is typing
• Useful when you allow the user to perform
searching and input specific information (e.g.
country names, addresses, etc.)
• You can use one of the following classes
depending on your requirements
› AutoCompleteTextView
› MultiAutoCompleteTextView
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Auto-complete Text Views
• Adding AutoCompleteTextView to your Activity
<AutoCompleteTextView
android:id="@+id/ac1"
android:layout_width="match_parent"
android:layout_height="wrap_content“/>
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Auto-complete Text Views
• Auto-complete involves providing a candidate list, this is done by using an
adapter (similar to what you do when using ListView)
• For example, the following use a pre-defined string array as a candidate
list
AutoCompleteTextView ac = (AutoCompleteTextView)
findViewById(R.id.autoCompleteTextView1);
String[] countries = new String[] {
“Algeria”, “Belgium”, “Canada”, “Denmark”, “Ethiopia”, “France”
};
ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, countries);
ac.setAdapter(adapter);
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Auto-complete Text Views
• What if you don’t want to hard-code the list of candidates in the app?
• You need to send the intermediate input of the user to the server, and use
the data returned by the server to update the data in the adapter
User input texts in the
AutoCompleteTextView
Extract data from the
response of the server
Submit texts input by the
user to the server
Update data in the
adapter of the
AutoCompleteTextView
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ac.addTextChangedListener(new TextWatcher() {
@Override
public void afterTextChanged(Editable s) {
final String query = s.toString().trim();
if (query.length() > 1) {
AsyncHttpClient client = new AsyncHttpClient();
RequestParams params = new RequestParams();
params.put("query", query);
client.get(url, parmas, new TextHttpResponseHandler() {
@Override
public void onSuccess(
int statusCode, Header[] headers, String response) {
// Extract data ...
// Update data of the adapter ...
adapter.notifyDataSetChanged();
}
});
}
}
});
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MultiAutoCompleteTextView
• MultiAutoCompleteTextView allows user to input multiple items separated
by a separator (e.g. a comma)
• Suggestions will be provided for the latest item in the text view
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Gradle
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Gradle
• Gradle is the official build tool for Android applications
• It helps you build (compile), test, run and package your apps
• It is integrated into Android Studio through the Android Gradle Plugin
• It can also be executed independently from the command line
Reference: http://gradle.org/
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Gradle
• The Gradle build process
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What are the benefits?
• Using Gradle allows you to
› Configure and customise the build process
› Create different versions of your app with different features, settings or
parameters under the same project
› Easily incorporate third-party modules into your application
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Build Configuration
• An Android Studio project contain a
top-level build file and a build file for
each module (‘app’ is a module in the
project)
• The build files are all named
‘build.gradle’
• In most cases, you only need to
modify the build files at the module
level
Reference: http://developer.android.com/tools/building/configuring-gradle.html
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apply plugin: 'com.android.application'
android {
compileSdkVersion 23
buildToolsVersion "23.0.2"
Apply the Android plugin for
Gradle in this build
Build Configuration
defaultConfig {
Configure the core settings and entries
applicationId "hk.edu.cuhk.ie.iems5722"
minSdkVersion 15
in the AndroidManifest.xml file
targetSdkVersion 23
versionCode 1
versionName "1.0"
}
buildTypes {
Specify different build
release {
types. The two default build
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'),
types are “debug” and
'proguard-rules.pro'
“release”.
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:23.1.1'
}
Declare dependencies to
libraries, jar files, remote
packages
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Product Flavours
• When publishing an
app, you might want to
publish different
variants of the app,
which features different
functions
• You can specify
different “product
flavours” in the
build.gradle file, and
specify their individual
parameters
}
productFlavors {
pro {
applicationId = "com.iems5722.pro"
}
free {
applicationId = "com.iems5722.free"
}
buildTypes {
debug {
applicationIdSuffix ".debug"
}
}
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Using BuildConfig
• You can specify constant values in the build.gradle file, and use them in
your Java code
• When building, different build types or product flavours will use the
corresponding values automatically
• Steps:
1. Specify constant values in build.gradle using buildConfigField
2. Use the values in your Java code using the BuildConfig class
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Using BuildConfig
android {
buildTypes {
debug {
buildConfigField ‘int’, ‘CREDITS’, ‘10000’
buildConfigField ‘String’, ‘APP_NAME’, ‘“APP DEBUG VERSION”’
buildConfigField ‘boolean’, ‘LOG’, ‘true’
}
}
}
release {
buildConfigField ‘int’, ‘CREDITS’, ’10’
buildConfigField ‘String’, ‘FOO_STRING’, ‘“APP”’
buildConfigField ‘boolean’, ‘LOG’, ‘false’
}
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Using BuildConfig
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
int credits = BuildConfig.CREDITS;
String app_name = BuildConfig.APP_NAME;
boolean log = BuildConfig.LOG;
}
...
}
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Using BuildConfig
• In developing client-server systems, one scenario in which you will use
BuildConfig is to specify the URL to the APIs for the debug and release build
types of your app
android {
buildTypes {
debug {
buildConfigField ‘String’, ‘DOMAIN’, ‘dev.myapp.com’
}
}
}
release {
buildConfigField ‘int’, ‘DOMAIN’, ‘api.myapp.com’
}
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ProGuard
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ProGuard
• ProGuard is a tool that helps you shrinks, optimises, and ofuscates the
codes of your app
• It does so by removing unused code, renaming classes, fields, and methods
with semantically obscure names
• Why?
› Creates an APK file with smaller size
› Makes the app more difficult to reverse engineer
Reference:
http://developer.android.com/tools/help/proguard.html
http://proguard.sourceforge.net/
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ProGuard
• ProGuard will only be run when you build your application in release mode
(and if you have enabled it)
• To enable ProGuard:
android {
...
}
Set minifyEnabled to true
buildTypes {
release {
minifyEnabled true
proguardFiles getDefaultProguardFile('proguard-android.txt'),
'proguard-rules.pro'
}
The file containing the
}
customised rules
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Configuring ProGuard
• In some cases, ProGuard might not analyse your code correctly, and might
remove codes that are actually required in your app
• You should specifically ask ProGuard to not modify some of the codes in
your app when necessary
• Whenever you see ClassNotFoundException when building your app for
release, you can add lines in the following format to the
proguard-rules.pro files in the app module
-keep public class com.iems5722.app.MyClass001
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Project Presentations
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Project
• To facilitate testing and marking, please name the package of your app
using the following format:
com.iems5722.groupX (Replace X with your group number)
• Send your app’s APK file (or a link to that file if it is too large) to my email
([email protected]) before the end of 26th April, 2017
(Wednesday)
• The APK files will be shared to the class so that everyone can try your apps
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Project Presentations
• You will have your project presentations on 27th April, 2017 (Thursday)
• Each group will have 6 minutes to present their app
• Your presentation slides should follow the format below:
1. Introduction: what is the app you have developed? (1 slides)
2. Functions: what are the major functions? (1-2 slides with screenshots)
3. Demonstration: 3 mins video (a trial run / an example usage / demonstrate most
important features)
4. What is the most challenging part? (name 1 issue, and describe how you solved it)
5.
What additional things will you add if you have more time?
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Project Presentations
• Send you a link to the project report and all source codes to my email
([email protected]) on or before 4th May, 2017 (Thursday)
• What should you include in your report:
1. Problem definition
what problem does your app try to solve?
2. Features / Functions
what are the major (networking) functions of the app? (with screenshots)
3. System architecture
(use diagrams and illustrations to describe how does the system (client/server) works)
(no need to describe specific implementation of the UI)
4.
How would you further improve it?
5.
A list of third party libraries that you have used in your project
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End of Lecture 12
Looking forward to
your project presentations!
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