Learn all about Android App Development

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Learn all about Android App Development:

Learn all about Android App Development Accessing Sensors and the Network

Topics:

Topics Background Introduction to Android Overview of Sensors Programming Tutorial 1: Tracking location with GPS and Google Maps Overview of Networking Programming Tutorial 2: Downloading from the Internet Programming Tutorial 3: Sending/Receiving SMS Messages Questions/Comments Resources

Introduction to Android:

Introduction to Android A brief guide to the Android Application Development Environment

Background:

Background Software platform from Google and the Open Handset Alliance July 2005, Google acquired Android, Inc. November 2007, Open Handset Alliance formed to develop open standards for mobile devices October 2008, Android available as open source December 2008, 14 new members joined Android project

Update History:

Update History April 30, 2009: Official 1.5 Cupcake release September 15, 2009: 1.6 SDK Donut release October 26, 2009: 2.0 SDK Éclair release Updates to the Éclair release: 2.0.1 on December 3, 2009 2.1 on January 12, 2010

Platform Versions:

Platform Versions

Android and the Hardware:

Android and the Hardware Built-in Apps ≡ Apps created in SDK Leverage Linux kernel to interface with hardware Open source platform promotes development from global community

Android Features:

Android Features Reuse and replacement of components Dalvik virtual machine Integrated browser Optimized graphics SQLite Media support GSM Telephony Bluetooth, EDGE, 3G, and WiFi Camera, GPS, compass, and accelerometer Rich development environment

Android Architecture:

Android Architecture

Application Fundamentals:

Application Fundamentals Apps are written in Java Bundled by Android Asset Packaging Tool Every App runs its own Linux process Each process has it’s own Java Virtual Machine Each App is assigned a unique Linux user ID Apps can share the same user ID to see each other’s files

Application Components:

Application Components Activity Present a visual user interface for one focused endeavor the user can undertake Example: a list of menu items users can choose from Services Run in the background for an indefinite period of time Example: calculate and provide the result to activities that need it Broadcast Receivers Receive and react to broadcast announcements Example: announcements that the time zone has changed Content Providers Store and retrieve data and make it accessible to all applications Example: Android ships with a number of content providers for common data types (e.g., audio, video, images, personal contact information, etc.) Intents Hold the content of a message Example: convey a request for an activity to present an image to the user or let the user edit some text

Installation:

Installation http://developer.android.com/sdk/installing.html Preparing your system and system requirements Downloading and Installing the SDK Installing ADT plug-in for Eclipse Adding Platforms and Components Exploring the SDK Completing tutorials Troubleshooting

Overview of Sensors:

Overview of Sensors The Android Sensor Platform and how to use it

Open Source Platform:

Open Source Platform Developer’s are able to access “goodies” Hardware capabilities made available

Hardware-oriented Features:

Hardware-oriented Features Feature Description Camera A class that enables your application to interact with the camera to snap a photo, acquire images for a preview screen, and modify parameters used to govern how the camera operates. Sensor Class representing a sensor. Use getSensorList ( int ) to get the list of available Sensors. SensorManager A class that permits access to the sensors available within the Android platform. SensorEventListener An interface u sed for receiving notifications from the SensorManager when sensor values have changed. An application implements this interface to monitor one or more sensors available in the hardware. SensorEvent This class represents a sensor event and holds information such as the sensor type (e.g., accelerometer, orientation, etc.), the time-stamp, accuracy and of course the sensor's data. MediaRecorder A class, used to record media samples, that can be useful for recording audio activity within a specific location (such as a baby nursery). Audio clippings can also be analyzed for identification purposes in an access-control or security application. For example, it could be helpful to open the door to your time-share with your voice, rather than having to meet with the realtor to get a key. GeomagneticField This class is used to estimated estimate magnetic field at a given point on Earth, and in particular, to compute the magnetic declination from true north. FaceDetector A class that permits basic recognition of a person's face as contained in a bitmap. Using this as a device lock means no more passwords to remember — biometrics capability on a cell phone.

Sensor and SensorManager:

Sensor and SensorManager Sensor type (Sensor class) Orientation, accelerometer, light, magnetic field, proximity, temperature, etc. Sampling rate Fastest, game, normal, user interface. When an application requests a specific sampling rate, it is really only a hint, or suggestion, to the sensor subsystem. There is no guarantee of a particular rate being available. Accuracy High, low, medium, unreliable.

Simulating an Android application that accesses positioning sensors -- Programming Tutorial:

Simulating an Android application that accesses positioning sensors -- Programming Tutorial

Preparing for the Tutorial:

Preparing for the Tutorial Must have Eclipse IDE installed Must have Android SDK installed Must have knowledge of Java Must have the external Google Maps library installed in your SDK environment. The Maps library is included with the Google APIs add-on, which you can install using the Android SDK and AVD Manager.

Get a Google Maps API Key:

Get a Google Maps API Key A Google Maps API key is required to integrate Google Maps into your Android application. To apply for a key: Locate the SDK debug certificate in the default folder of "C:\Documents and Settings\<username>\Local Settings\Application Data\Android". The filename of the debug keystore is debug.keystore . Copy the debug.keystore file to a folder named C:\Android\. Open the command window and navigate to C:\Program Files\Java\< JDK_version_number >\bin to locate the Keytool.exe. Execute the following to extract the MD5 fingerprint: keytool.exe -list -alias androiddebugkey - keystore "C:\Android\debug.keystore" - storepass android - keypass android Copy the MD5 certificate fingerprint and navigate your web browser to: http://code.google.com/android/maps-api-signup.html. Follow the instructions on the page to complete the application and obtain the Google Maps key. For more information on using Google Maps in Android application development: http://mobiforge.com/developing/story/using-google-maps-android

Create an Android Virtual Device (AVD):

Create an Android Virtual Device (AVD) Defines the system image and device settings used by the Emulator To create an AVD in Eclipse: Select Window > Android SDK and AVD Manager. The Android SDK and AVD Manager displays. Make sure the entry for Virtual Devices is selected and click New. The Create new AVD window displays. Enter a Name for the AVD. Select Google APIs (API level 3) as the Target. Click Create AVD. Close the Android SDK and AVD Manager.

Create the Android Project:

Create the Android Project To create the project in Eclipse: Select File > New > Project. Select Android Project in the Android folder and click Next. Enter GPSSimulator as the Project Name. Select Google APIs (Platform 1.5) as the Build Target. Enter GPSSimulator as the Application name. Enter com.android.gpssimulator as the Package name. Enter GPSSimulator as the Activity name. Click Finish.

The New Android Project:

The New Android Project

Modify the AndroidManifest.xml File:

Modify the AndroidManifest.xml File Add permissions for GPS To modify the AndroidManifest.xml file: Click on the res folder in the GPSSimulator project. Double-click AndroidManifest.xml to display the GPSSimulator Manifest. Enter the following lines before the application tag. <uses-permission android:name =“ android.permission.ACCESS_FINE_LOCATION ” /> Save the changes to the file.

Add LocationManager to get Updates:

Add LocationManager to get Updates public class GPSSimulator extends Activity { private LocationManager lm; private LocationListener locationListener; // Called when the activity is first created. @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); // use the LocationManager class to obtain GPS locations lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); locationListener = new MyLocationListener(); lm.requestLocationUpdates( LocationManager.GPS_PROVIDER, 0, 0, locationListener); } }

Add MyLocationListener:

Add MyLocationListener private class MyLocationListener implements LocationListener { @Override public void onLocationChanged (Location loc) { if (loc != null) { Toast.makeText ( getBaseContext (), "Location changed : Lat: " + loc.getLatitude () + " Lng : " + loc.getLongitude (), Toast.LENGTH_SHORT ).show(); } } @Override public void onProviderDisabled (String provider) { // TODO Auto-generated method stub } @Override public void onProviderEnabled (String provider) { // TODO Auto-generated method stub } @Override public void onStatusChanged (String provider, int status, Bundle extras) { // TODO Auto-generated method stub } }

Test the GPSSimulator:

Test the GPSSimulator To test in Eclipse: Switch to DDMS view. Find the Location Controls in the Emulator Control tab. Click the GPX tab and click Load GPX. Locate and select the GPX file. Click Play to begin sending coordinates to the Emulator.

Add ability to use Google Maps:

Add ability to use Google Maps Update the Manifest with two lines. <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android ="http://schemas.android.com/apk/res/android" package=" com.android.GPSSimulator "> <uses-permission android:name =" android.permission.INTERNET " /> <uses-permission android:name =" android.permission.ACCESS_FINE_LOCATION " /> <application android:icon ="@ drawable /icon" android:label ="@string/ app_name "> <uses-library android:name =" com.google.android.maps " /> <activity android:name =".GPS" android:label ="@string/ app_name "> <intent-filter> <action android:name =" android.intent.action.MAIN " /> <category android:name =" android.intent.category.LAUNCHER " /> </intent-filter> </activity> </application> </manifest>

Add MapView to main.xml:

Add MapView to main.xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <com.google.android.maps.MapView android:id="@+id/mapview1" android:layout_width="fill_parent" android:layout_height="fill_parent" android:enabled="true" android:clickable="true" android:apiKey=“Your API Key Here" /> </LinearLayout>

Modify GPSSimulator to use Google Maps:

Modify GPSSimulator to use Google Maps public class GPSSimulator extends MapActivity { private LocationManager lm; private LocationListener locationListener ; private MapView mapView ; private MapController mc; // Called when the activity is first created. @Override public void onCreate (Bundle savedInstanceState ) { super.onCreate ( savedInstanceState ); setContentView ( R.layout.main ); // use the LocationManager class to obtain GPS locations lm = ( LocationManager ) getSystemService ( Context.LOCATION_SERVICE ); locationListener = new MyLocationListener (); lm.requestLocationUpdates ( LocationManager.GPS_PROVIDER , 0, 0, locationListener ); mapView = ( MapView ) findViewById (R.id.mapview1); mc = mapView.getController (); } @Override protected boolean isRouteDisplayed () { return false; } private class MyLocationListener implements LocationListener { @Override public void onLocationChanged (Location loc) { if (loc != null) { Toast.makeText ( getBaseContext (), "Location changed : Lat: " + loc.getLatitude () + " Lng : " + loc.getLongitude (), Toast.LENGTH_SHORT ).show(); GeoPoint p = new GeoPoint ( ( int ) ( loc.getLatitude () * 1E6), ( int ) ( loc.getLongitude () * 1E6)); mc.animateTo (p); mc.setZoom (16); mapView.invalidate (); } } @Override public void onProviderDisabled (String provider) { } @Override public void onProviderEnabled (String provider) { } @Override public void onStatusChanged (String provider, int status, Bundle extras) { } } }

View the Location on the Map:

View the Location on the Map

Internet Layers:

Internet Layers The Internet, is based on a layered architecture called the TCP/IP stack. Link Layer Protocols: ARP and RARP Internet Layer Protocols: IP, ping, etc. Transport Protocols: TCP and UDP Application Layer Protocols: HTTP, FTP, DNS, etc.

Client-Server Communication:

Client-Server Communication A server machine is identified on the Internet by some IP address Daemons are the processes running in the background which are listening all the time for connection requests from clients on a particular port number. Once a connection request comes into the server on a given port, the corresponding daemon can choose to accept it, and if so, a connection is established. Then the application layer protocol is typically used for the client to get or send data to the server.

Accessing a website from the Android Emulator --Programming Tutorial 2:

Accessing a website from the Android Emulator -- Programming Tutorial 2

Required Packages:

Required Packages Package Description org.apache .* Represents a number of packages that provide fine control and functions for HTTP communications. You might recognize Apache as the popular open source Web server. android.net Contains additional network access sockets beyond the core java.net.* classes. This package includes the URI class, which is used frequently in Android application development beyond traditional networking. android.net.http Contains classes for manipulating SSL certificates. android.net.wifi Contains classes for managing all aspects of WiFi (802.11 wireless Ethernet) on the Android platform. Not all devices are equipped with WiFi capability, particularly as Android makes headway in the "flip-phone" strata of cell phones from manufacturers like Motorola and LG. android.telephony Contains classes required for managing and sending SMS (text) messages. Over time, an additional package will likely be introduced to provide similar functions on non-GSM networks, such as CDMA, or something like android.t lephony.cdma .

Layout:

Layout

Link Activity and View:

Link Activity and View View object may have an integer ID associated with it android:id="@+id/my_button“ To get the reference of the view object in activity Button myButton = (Button)findViewById(R.id.my_button);

Adding Event to View Object:

Adding Event to View Object View.OnClickListener() Interface definition for a callback to be invoked when a view is clicked.  onClick(View v) Called when a view has been clicked. Inside this function you can specify what actions to perform on a click.

Strings.xml:

Strings.xml

AndroidManifest.xml:

AndroidManifest.xml

Network Settings :

Network Settings If you are using the emulator then there are limitations. Each instance of the emulator runs behind a virtual router/firewall service that isolates it from your development machine's network interfaces and settings and from the internet. Communication with the emulated device may be blocked by a firewall program running on your machine. Reference

Behind Proxy Server:

Behind Proxy Server

Behind Proxy Server:

Behind Proxy Server

Behind Proxy Server:

Behind Proxy Server

Behind Proxy Server:

Behind Proxy Server

Behind Proxy Server:

Behind Proxy Server

Behind Proxy Server:

Behind Proxy Server

App to Download jpg file:

App to Download jpg file Step1 Add permissions to AndroidManifest.xml <uses-permission android:name =" android.permission.INTERNET " /> Step 2 Import files import java.io.IOException ; import java.io.InputStream ; import java.io.InputStreamReader ; import java.net.HttpURLConnection ; import java.net.URL; import java.net.URLConnection ; import android.app.Activity ; import android.graphics.Bitmap ; import android.graphics.BitmapFactory ; import android.os.Bundle ; import android.widget.ImageView ; import android.widget.TextView ; import android.widget.Toast ;

App to Download jpg file:

App to Download jpg file Step 3 Writing OpenHttpConnection() To open a connection to a HTTP server using OpenHttpConnection() We first create an instance of the URL class and initialize it with the URL of the server When the connection is established, you pass this connection to an URLConnection object. To check if the connection established is using a HTTP protocol. The URLConnection object is then cast into an HttpURLConnection object and you set the various properties of the HTTP connection. Next, you connect to the HTTP server and get a response from the server. If the response code is HTTP_OK, you then get the InputStream object from the connection so that you can begin to read incoming data from the server The function then returns the InputStream object obtained.

App to Download jpg file:

App to Download jpg file public class HttpDownload extends Activity { /** Called when the activity is first created.*/ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } private InputStream OpenHttpConnection(String urlString) throws IOException { InputStream in = null; int response = -1; URL url = new URL(urlString); URLConnection conn = url.openConnection(); if (!(conn instanceof HttpURLConnection)) throw new IOException("Not an HTTP connection"); try{ HttpURLConnection httpConn = ( HttpURLConnection ) conn; httpConn.setAllowUserInteraction (false); httpConn.setInstanceFollowRedirects (true); httpConn.setRequestMethod ("GET"); httpConn.connect (); response = httpConn.getResponseCode (); if (response == HttpURLConnection.HTTP_OK ) { in = httpConn.getInputStream (); } } catch (Exception ex) { throw new IOException ("Error connecting"); } return in; } }

App to Download jpg file:

App to Download jpg file Step 4 Modify the Main.xml code <?xml version="1.0" encoding="utf-8"?> < LinearLayout xmlns:android ="http://schemas.android.com/ apk /res/android" android:orientation ="vertical" android:layout_width =" fill_parent " android:layout_height =" fill_parent " > < ImageView android:id ="@+id/ img " android:layout_width =" wrap_content " android:layout_height =" wrap_content " android:layout_gravity ="center" /> < TextView android:id ="@+id/text" android:textStyle ="bold" android:layout_width =" wrap_content " android:layout_height =" wrap_content " /> </ LinearLayout >

App to Download jpg file:

App to Download jpg file Step 5 writing DownloadImage() The DownloadImage() function takes in a string containing the URL of the image to download. It then calls the OpenHttpConnection() function to obtain an InputStream object for reading the image data. The InputStream object is sent to the decodeStream() method of the BitmapFactory class. The decodeStream() method decodes an InputStream object into a bitmap. The decoded bitmap is then returned by the DownloadImage() function . private Bitmap DownloadImage(String URL) { Bitmap bitmap = null; InputStream in = null; try { in = OpenHttpConnection(URL); bitmap = BitmapFactory.decodeStream(in); in.close(); } catch (IOException e1) { e1.printStackTrace(); } return bitmap; }

Slide52:

Step 6 T est the DownloadImage() function, modify the onCreate() event as follows @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Bitmap bitmap = DownloadImage( "http://www.streetcar.org/mim/cable/images/cable-01.jpg"); img = (ImageView) findViewById(R.id.img); img.setImageBitmap(bitmap); }

App to Download jpg file:

App to Download jpg file Step 7:Output

Transmitting SMS messages across the network --Programming Tutorial 3:

Transmitting SMS messages across the network -- Programming Tutorial 3

Intent and IntentFilter:

Intent and IntentFilter Intents request for an action to be performed and supports interaction among the Android components. For an activity it conveys a request to present an image to the user For broadcast receivers, the Intent object names the action being announced. Intent Filter Registers Activities, Services and Broadcast Receivers(as being capable of performing an action on a set of data).

SMS Sending:

SMS Sending STEP 1 In the AndroidManifest.xml file, add the two permissions - SEND_SMS and RECEIVE_SMS. STEP 2 In the main.xml, add Text view to display "Enter the phone number of recipient“ and "Message" EditText with id txtPhoneNo and txtMessage Add the button ID "Send SMS“

SMS Sending:

SMS Sending Step 3 Import Classes and Interfaces import android.app.Activity ; import android.app.PendingIntent ; import android.content.Intent ; import android.os.Bundle ; import android.telephony.SmsManager ; import android.view.View ; import android.widget.Button ; import android.widget.EditText ; import android.widget.Toast ;

SMS Sending:

SMS Sending Step 4 Write the SMS class public class SMS extends Activity { Button btnSendSMS ; EditText txtPhoneNo ; EditText txtMessage ; /** Called when the activity is first created. */ @Override public void onCreate (Bundle savedInstanceState ) { super.onCreate ( savedInstanceState ); setContentView ( R.layout.main ); btnSendSMS = (Button) findViewById ( R.id.btnSendSMS ); txtPhoneNo = ( EditText ) findViewById ( R.id.txtPhoneNo ); txtMessage = ( EditText ) findViewById ( R.id.txtMessage ); btnSendSMS.setOnClickListener (new View.OnClickListener () { public void onClick (View v) { String phoneNo = txtPhoneNo.getText ().toString(); String message = txtMessage.getText ().toString(); if ( phoneNo.length ()>0 && message.length ()>0) sendSMS ( phoneNo , message); else Toast.makeText ( getBaseContext (), "Please enter both phone number and message.", Toast.LENGTH_SHORT ).show(); } }); } } Input from the user (i.e., the phone no, text message and sendSMS is implemented).

SMS Sending:

SMS Sending Step 5 To send an SMS message, you use the SmsManager class. And to instantiate this class call getDefault () static method. The sendTextMessage () method sends the SMS message with a PendingIntent . The PendingIntent object is used to identify a target to invoke at a later time. private void sendSMS (String phoneNumber , String message) { PendingIntent pi = PendingIntent.getActivity (this, 0, new Intent(this, SMS.class ), 0); SmsManager sms = SmsManager.getDefault (); sms.sendTextMessage ( phoneNumber , null, message, pi, null); }

SMS Sending:

SMS Sending

Receiving SMS:

Receiving SMS Step 1

Receiving SMS:

Receiving SMS Step 2 In the AndroidManifest.xml file add the <receiver> element so that incoming SMS messages can be intercepted by the SmsReceiver class. <receiver android:name=".SmsReceiver"> <intent-filter> <action android:name= "android.provider.Telephony.SMS_RECEIVED" /> </intent-filter> </receiver>

Receiving SMS:

Receiving SMS Step 3 import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.telephony.SmsMessage; import android.widget.Toast;

Receiving SMS:

Receiving SMS Step 4 public class SmsReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { //---get the SMS message passed in--- Bundle bundle = intent.getExtras(); SmsMessage[] msgs = null; String str = ""; if (bundle != null){ //---retrieve the SMS message received--- Object[] pdus = (Object[]) bundle.get("pdus"); msgs = new SmsMessage[pdus.length]; for (int i=0; i<msgs.length; i++) { msgs[i] = SmsMessage.createFromPdu((byte[])pdus[i]); str += "SMS from " + msgs[i].getOriginatingAddress(); str += " :"; str += msgs[i].getMessageBody().toString(); str += "\n"; } //---display the new SMS message--- Toast.makeText(context, str, Toast.LENGTH_SHORT).show(); } } } In the SmsReceiver class, extend the BroadcastReceiver class and override the onReceive () method. The message is attached to the Intent The messages are stored in a object array PDU format. To extract each message, you use the static createFromPdu () method from the SmsMessage class. The SMS message is then displayed using the Toast class

Receiving SMS:

Receiving SMS

Conclusions:

Conclusions What is Android? What are the sensor and networking capabilities in Android? How to use location data and Google maps in Android? How to access websites? How to send SMS messages across the network? Questions/Comments?

Resources:

Resources Ableson , Frank. “Tapping into Android’s sensors.” www.ibm.com. January 30, 2010. http://www.ibm.com/developerworks/opensource/library/os-android-sensor/index.html Ableson , Frank; Collins, Charlie; Sen , Robi . Unlocking Android, A Developer’s Guide. Greenwich: Manning Publications Co. 2009. Android Development Guide. January 30, 2010. http://developer.android.com/guide/index.html Lee, Wei- Meng . “Using Google Maps in Android.” mobiforge.com. January 30, 2010. http://mobiforge.com/developing/story/using-google-maps-android Lee, Wei- Meng . “You Are Here: Using GPS and Google Maps in Android.” www.devx.com. January 30, 2010. http://www.devx.com/wireless/Article/39239/1954 Lee, Wei- Meng “SMS Messaging in Android” mobiforge.com. January 30, 2010 http://mobiforge.com/developing/story/sms-messaging-android Lee, Wei- Meng “Connecting to the Web: I/O Programming in Android” November 5, 2008   Android ”http :// www.devx.com /wireless/Article/39810 Open Handset Alliance, http://www.openhandsetalliance.com/ Patterson, Don. “Android Development Guide.” getsatisfaction.com. January 30, 2010. http://getsatisfaction.com/luci/topics/android_development_guide www.androidcompetencycenter.com. January 30, 2010. http://www.androidcompetencycenter.com/2009/06/accessing-device-sensors Xianhua Shu ; Zhenjun Du; Rong Chen, "Research on Mobile Location Service Design Based on Android," Wireless Communications, Networking and Mobile Computing, 2009. WiCom '09. 5th International Conference on , vol., no., pp.1-4, 24-26 Sept. 2009 http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=5302615&isnumber=5300799

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