IEMS 5722 Mobile Network Programming and Distributed Server Architecture

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1 Department of Information Engineering, CUHK MScIE 2 nd Semester, 2016/17 IEMS 5722 Mobile Network Programming and Distributed Server Architecture Lecture 12 Advanced Android Programming Lecturer: Albert C. M. Au Yeung 30 th March, 2017

2 Google Play Services 2

3 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 3

4 Google Play Services Google Services API Requests and Responses Google Play App Store Your Mobile App Automatic Update GMS Client Library Google Play Services APK An Android Device 4

5 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: 5

6 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: 6

7 Accessing Google APIs You can create an instance of GoogleApiClient with connection to specific APIs by using a builder: public class MyActivity extends FragmentActivity implements OnConnectionFailedListener { private GoogleApiClient 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(); 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 //... 7

8 Google APIs for Android For a list of Google APIs for Android, see: 8

9 Location Detection 9

10 Location Detection Location detection is one of the most commonly used features of smartphones Many apps offers location-based services, e.g.: Maps, transportation and navigation Location-based social networking Tracking News Weather forecast... 10

11 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 Wi-Fi + IP Address 4. Others 11

12 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 12

13 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"/> 13

14 Google Play Services Location APIs The flow of setting up the app to use the location APIs Connect to Google Play services 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 14

15 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. 15

16 1. Connecting to Google Play Services Connect the API client when the activity is started, and disconnect when it is protected void onstart() { super.onstart(); if (mgoogleapiclient!= null) { protected void onstop() { if (mgoogleapiclient!= null) { mgoogleapiclient.disconnect(); super.onstop(); 16

17 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 {... 17

18 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 Submit location request with parameters Android System Your App Send location updates when there is changes or according to a preset frequency 18

19 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.: 19

20 3. Request Location Updates Once the API client is connected, you can submit your location 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. 20

21 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 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()));... 21

22 5. Receiving Location Updates Finally, set up the callback functions so that you can receive location 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

23 Stop Receiving Location Updates To save power, you should stop requesting location updates when it is no longer necessary. For protected void onpause() { super.onpause(); LocationServices.FusedLocationApi.removeLocationUpdates( mgoogleapiclient, public void onresume() { super.onresume(); if (mgoogleapiclient.isconnected()) { LocationServices.FusedLocationApi.requestLocationUpdates( mgoogleapiclient, mlocationrequest, this); 23

24 Using Google Maps 24

25 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: Provide interactive maps with 3D maps, satellite view, terrain view, road maps, etc. Allow overlaying of different components, such as markers, polygons, etc. Control user s view such as rotation, zoom, pan Street view 25

26 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: 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"/> 26

27 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=" android:name="com.google.android.gms.maps.mapfragment" android:id="@+id/map" android:layout_width="match_parent" android:layout_height="match_parent"/> 27

28 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 public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.main); MapFragment mapfragment = (MapFragment) getfragmentmanager().findfragmentbyid(r.id.map); public void onmapready(googlemap map) { map.addmarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker")); 28

29 Other Maps SDKs Nokia HERE Map OpenStreetMap Baidu Map 29

30 Geocoding & Reverse Geocoding 30

31 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 31

32 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: 32

33 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) 33

34 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 34

35 Other Cloud Services 35

36 Cloud Services & APIs Facebook Instagram WeChat Baidu YouTube IBM Developer Cloud 36

37 Auto-complete Text Views 37

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

38 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 38

39 Auto-complete Text Views Adding AutoCompleteTextView to your Activity <AutoCompleteTextView android:layout_width="match_parent" android:layout_height="wrap_content /> 39

40 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); 40

41 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 41

42 ac.addtextchangedlistener(new TextWatcher() 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() public void onsuccess( int statuscode, Header[] headers, String response) { // Extract data... // Update data of the adapter... adapter.notifydatasetchanged(); ); ); 42

43 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 43

44 Gradle 44

45 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: 45

46 Gradle The Gradle build process 46

47 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 47

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

48 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: 48

49 apply plugin: 'com.android.application' android { compilesdkversion 23 buildtoolsversion "23.0.2" Apply the Android plugin for Gradle in this build Build Configuration defaultconfig { applicationid "hk.edu.cuhk.ie.iems5722" minsdkversion 15 targetsdkversion 23 versioncode 1 versionname "1.0" buildtypes { release { minifyenabled false proguardfiles getdefaultproguardfile('proguard-android.txt'), 'proguard-rules.pro' Configure the core settings and entries in the AndroidManifest.xml file Specify different build types. The two default build types are debug and 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 49

50 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" 50

51 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 51

52 Using BuildConfig android { buildtypes { debug { buildconfigfield int, CREDITS, 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 52

53 Using BuildConfig public class MainActivity extends AppCompatActivity 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;... 53

54 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 54

55 ProGuard 55

56 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:

57 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 57

58 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 58

59 Project Presentations 59

60 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 (cmauyeung@ie.cuhk.edu.hk) before the end of 26 th April, 2017 (Wednesday) The APK files will be shared to the class so that everyone can try your apps 60

61 Project Presentations You will have your project presentations on 27 th 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? 61

62 Project Presentations Send you a link to the project report and all source codes to my (cmauyeung@ie.cuhk.edu.hk) on or before 4 th 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 62

63 End of Lecture 12 Looking forward to your project presentations! 63

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