Native Android Development Practices

• Roy Clarkson & Josh LongSpringSource, a division of VMware

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Native Android Development Practices

@royclarkson

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About Roy Clarkson (Spring Android Lead)

@royclarkson

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About Roy Clarkson (Spring Android Lead)

@royclarkson

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About Roy Clarkson (Spring Android Lead)

@starbuxman

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About Josh Long (Spring Developer Advocate)

josh.long@springsource.com

Spring Mobile

• Provides support for developing mobile web applications– Builds on Spring MVC, focuses on server-side support– Compliments client-side mobile frameworks

• Key Features– Device Detection– Site Preference Management– Site Switcher

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Device Detection

• Useful when requests by mobile devices need to be handled differently from requests made by desktop browsers

• Introspects HTTP requests to determine the device that originated the request.– Achieved by analyzing the User-Agent header and other

request headers– In contrast to “Feature Detection” where client detects

available features

• Spring Mobile provides a DeviceResolver abstraction and interceptor

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Device Detection Demo

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Site Preference Management

• Device detection is often used to determine which "site" will be served to the user– Mobile site vs. desktop site

• Spring Mobile also provides support for “site preference management”

• Allows the user to indicate whether he or she prefers the mobile site or the normal site

• Remembers the user’s preference for their session

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Site Preference Demo

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Site Switcher

• Some applications may wish to host their "mobile site" at a different domain from their "normal site"– For example, Google will switch you to m.google.com if you

access google.com from your mobile phone

• SiteSwitcherHandlerInterceptor can be used to redirect mobile users to a dedicated mobile site

• Supported SiteSwitchers– mDot - m.example.com– dotMobi - example.mobi

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Site Switcher Demo

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Limitations of Mobile web sites

• they can’t access the native capabilities of the phone• they require network access (no offline support)• formatting an application to look mobile is different than

actually being a mobile application

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Agenda

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Agenda

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Agenda

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An Introduction to Android!

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More than 500,000 activations every day

An Introduction to Android!

• Huge and growing ecosystem ofapplications and a market to boot

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8.1 billion app downloadsAndroid Market PlaceApple App Store 6 billion

* http://news.cnet.com/8301-1035_3-20103230-94/android-to-overtake-apple-in-app-downloads/

Expected downloads in 2011

Easy to get started

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• Programs are written in Java ( )

Easy to get started

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• Programs are written in Java ( )

Easy to get started

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• Programs are written in Java ( )

Easy APIs and concepts

• no real “applications,” only loosely coupled components

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Activities describes the unit of work for one screen

Services does background work like synchronization with a cloud service

Content Providers component that knows how to render and manipulate content of a certain type

Broadcast Receivers knows how to receive and respond to system-wide events like screen shutoff.

* http://developer.android.com/guide/topics/fundamentals.html

A Simple Activity

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package org.springframework.android.activities;

import android.app.Activity;import android.os.Bundle;

public class HelloAndroid extends Activity {     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);    }

}

You *must* extend Android classes to build proper components

A Simple Activity

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package org.springframework.android.activities;

import android.app.Activity;import android.os.Bundle;

public class HelloAndroid extends Activity {     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);    }

}

You *must* extend Android classes to build proper components

R.* refers to constants that Android code generates for you that correspond to “resources”

A Simple Activity

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package org.springframework.android.activities;

import android.app.Activity;import android.os.Bundle;

public class HelloAndroid extends Activity {     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);    }

}

Declaring the Simple Activity

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<?xml version="1.0" encoding="utf-8"?><TextView xmlns:android="http://schemas.android.com/apk/res/android"  android:id="@+id/textview"  android:layout_width="fill_parent"  android:layout_height="fill_parent"  android:text="@string/hello"/>

/res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?><resources>    <string name="hello">Hello, Android! I am a string resource!</string>    <string name="app_name">Hello, Android</string></resources>

/res/values/strings.xml

Lifecycle

• Android controls lifecycles of these components• Registered in manifest

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<activity android:name=".activities.HelloAndroid          android:label="@string/app_name"           android:theme="@android:style/Theme.NoTitleBar"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter></activity>

Class is set relative to root package specified in manifest

Lifecycle

• Android controls lifecycles of these components• Registered in manifest

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<activity android:name=".activities.HelloAndroid          android:label="@string/app_name"           android:theme="@android:style/Theme.NoTitleBar"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter></activity>

you specify that an Activity is the primary one like this

Class is set relative to root package specified in manifest

Lifecycle

• Android controls lifecycles of these components• Registered in manifest

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<activity android:name=".activities.HelloAndroid          android:label="@string/app_name"           android:theme="@android:style/Theme.NoTitleBar"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter></activity>

Android Sample Demo

• How to use STS and the Android Eclipse plugin

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How can Maven help?

• Android4Maven– This project compiles android.jar from source and pulls out

source and resource files to replicate android.jar in the SDK– http://sourceforge.net/projects/android4maven/

• Maven Android SDK Deployer– If you need to use Google maps, then you have to go this

route– https://github.com/mosabua/maven-android-sdk-deployer

• Maven Android Plugin– Provides support for Maven dependency management within

Android projects– http://code.google.com/p/maven-android-plugin/

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Maven Android Plugin Configuration

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<plugins> <plugin> <groupId>com.jayway.maven.plugins.android.generation2</groupId> <artifactId>maven-android-plugin</artifactId> <version>2.8.4</version> <configuration> <sdk> <platform>3</platform> </sdk> <emulator> <avd>3</avd> </emulator> <deleteConflictingFiles>true</deleteConflictingFiles> <undeployBeforeDeploy>true</undeployBeforeDeploy> </configuration> <extensions>true</extensions> </plugin>

m2eclipse Support

• Maven Integration for Android Development Tools– An Eclipse plugin that adds support for integrating

m2eclipse, Android Developer Tools, and the Maven Android Plugin

– http://code.google.com/a/eclipselabs.org/p/m2eclipse-android-integration/

• Maven Android archetypes– This projects provides several Maven archetypes for

Android. These archetypes allow you to quickly bootstrap a Maven project to develop an android application.

– https://github.com/akquinet/android-archetypes

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http://blog.springsource.com/2010/12/17/spring-android-and-maven-part-1/http://blog.springsource.com/2010/12/17/spring-android-and-maven-part-2/

Running the simple Activity

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Running the simple Activity

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...what about something a bit more non-trivial?

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Spring’s aim:

bring simplicity to java development

modern web data access integration mobile social security

tc ServerTomcatJetty

lightweightCloudFoundry

Google App EngineAmazon Web Services

BeanStalkHeroku

the cloud: WebSphereJBoss ASWebLogic

(on legacy versions, too!)

traditional

The Spring framework

security

Enter Spring Android!

What problem are we trying to solve?

• Concerns– REST has become a popular choice for architecting both

public and private web services– The Android runtime provides HTTP clients capable of

making HTTP connections and requests, but it does not have a fully featured REST client

• Spring Android Solution– The goal of Spring Android Rest Template is to provide an

easy to use, and functional REST client that supports marshaling objects from XML and JSON.

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REST

• Origin– The term Representational State Transfer was introduced and

defined in 2000 by Roy Fielding in his doctoral dissertation.• His paper suggests these four design principles:

– Use HTTP methods explicitly.• POST, GET, PUT, DELETE• CRUD operations can be mapped to these existing methods

– Be stateless.• State dependencies limit or restrict scalability

– Expose directory structure-like URIs.• URI’s should be easily understood

– Transfer XML, JavaScript Object Notation (JSON), or both.• Use XML or JSON to represent data objects or attributes

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Basic Rest Template Example

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RestTemplate restTemplate = new RestTemplate();String url = "https://ajax.googleapis.com/ajax/services/search/web?v=1.0&q={query}";String result = restTemplate.getForObject(url, String.class, "SpringSource");

RestTemplate restTemplate = new RestTemplate();String url = "http://example.com/hotels/{hotel}/bookings/{booking}";String result = restTemplate.getForObject(url, String.class, "42", “21”);

§ Google search example

§ Multiple parameters

Demo

• Using Spring Android to communicate with a RESTful web service (Google Search Demo)

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Spring Android Rest Template

• Based on SpringFramework– The majority of the supporting classes are pulled from

SpringFramework.– Modifications were made to support Android.

• RestTemplate class is the heart of the library– Entry points for the six main HTTP methods

• DELETE - delete(...)• GET - getForObject(...)• HEAD - headForHeaders(...)• OPTIONS - optionsForAllow(...)• POST - postForLocation(...)• PUT - put(...)• any HTTP operation - exchange(...) and execute(...)

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Spring Android Rest Template

• Http Client– The HttpComponents HttpClient is a native HTTP client

available on the Android platform.– HttpComponentsClientHttpRequestFactory

• Message Converters– MappingJacksonHttpMessageConverter - object to

JSON marshaling supported via the Jackson JSON Processor

– SimpleXmlHttpMessageConverter - object to XML marshaling supported via the Simple XML Serializer

– SyndFeedHttpMessageConverter - RSS and Atom feeds supported via the Android ROME Feed Reader

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Spring Android Showcase

• Examples– HTTP GET

• JSON• XML

– HTTP GET with Parameters• JSON• XML

– HTTP POST• String• JSON• XML• MultiValueMap

– HTTP and GZIP

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Spring Android Demos

• Spring Android Showcase Demo

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Spring Social on Android

• Supports connecting to supported Spring Social services• uses same RESTful connectivity based on RestTemplate

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Enter Spring Android!

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do NOT reinvent the Wheel!

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Dependency Injection on Android

• Problems with DI on Android– hard reliance on base classes– hard reliance on Android to manage the runtime lifecycle

• a POJO peer system would have been onerous

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Dependency Injection on Android

• Lots of options– RoboGuice– Android Annotations– the Android way

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Dependency Injection on Android

• RoboGuice (http://code.google.com/p/roboguice/)– Pros:

• requires you to extend RoboApplication• You must configure your beans using the

AbstractAndroidModule• Each Activity must extend from RoboActivity

– Cons:• no AOP• not small, at all!

– (400kb to a mobile application may as well be 400MBs to your enterprise application!)

public class MyActivity extends Activity {     private TextView label;     private Drawable image;     private SearchManager searchManager;     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.myactivity);        this.label = (TextView) findViewById(R.id.mylabel);        this.image = getResources().getDrawable(R.drawable.myimage);        this.searchManager = (SearchManager) getSystemService(Activity.SEARCH_SERVICE);    }}

before RoboGuice

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Dependency Injection on Android

• RoboGuice (http://code.google.com/p/roboguice/)

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Dependency Injection on Android

• RoboGuice (http://code.google.com/p/roboguice/)

public class MyActivity extends RoboActivity {     @InjectView(R.id.mylabel)    TextView label;     @InjectResource(R.drawable.myimage)    Drawable image;     @Inject    SearchManager searchManager;     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.myactivity);    }}

with RoboGuice

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Dependency Injection on Android

• RoboGuice (http://code.google.com/p/roboguice/)

used to inject other widgets or “views”

public class MyActivity extends RoboActivity {     @InjectView(R.id.mylabel)    TextView label;     @InjectResource(R.drawable.myimage)    Drawable image;     @Inject    SearchManager searchManager;     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.myactivity);    }}

with RoboGuice

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Dependency Injection on Android

• RoboGuice (http://code.google.com/p/roboguice/)

used to inject Resources

used to inject other widgets or “views”

public class MyActivity extends RoboActivity {     @InjectView(R.id.mylabel)    TextView label;     @InjectResource(R.drawable.myimage)    Drawable image;     @Inject    SearchManager searchManager;     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.myactivity);    }}

with RoboGuice

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Dependency Injection on Android

• RoboGuice (http://code.google.com/p/roboguice/)

used to inject other objects

used to inject Resources

used to inject other widgets or “views”

public class MyActivity extends RoboActivity {     @InjectView(R.id.mylabel)    TextView label;     @InjectResource(R.drawable.myimage)    Drawable image;     @Inject    SearchManager searchManager;     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.myactivity);    }}

with RoboGuice

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Dependency Injection on Android

• RoboGuice (http://code.google.com/p/roboguice/)

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Dependency Injection on Android

• RoboGuice (http://code.google.com/p/roboguice/)– Pros:

• requires you to extend RoboApplication• You must configure your beans using the

AbstractAndroidModule• Each Activity must extend from RoboActivity

– Cons:• no AOP• not small, at all!

– (400kb to a mobile application may as well be 400MBs to your enterprise application!)

• runtime inefficiency

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Beyond Dependency Injection

• Android Annotations(http://code.google.com/p/androidannotations/)– Pros:

• compile-time code generation means no runtime cost• can be used side-by-side with RoboGuice

– Cons:• extra build step• some redundancy with RoboGuice

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Beyond Dependency Injection

• Android Annotations(http://code.google.com/p/androidannotations/)

@EActivity(R.layout.myactivity) public class MyActivity extends Activity {     @InjectView     TextView mylabel;     @DrawableRes(R.drawable.myimage)    Drawable image;     @SystemService    SearchManager searchManager;}

sets the layout

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Beyond Dependency Injection

• Android Annotations(http://code.google.com/p/androidannotations/)

@EActivity(R.layout.myactivity) public class MyActivity extends Activity {     @InjectView     TextView mylabel;     @DrawableRes(R.drawable.myimage)    Drawable image;     @SystemService    SearchManager searchManager;}

sets the layout

Inject another widget or “view”

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Beyond Dependency Injection

• Android Annotations(http://code.google.com/p/androidannotations/)

@EActivity(R.layout.myactivity) public class MyActivity extends Activity {     @InjectView     TextView mylabel;     @DrawableRes(R.drawable.myimage)    Drawable image;     @SystemService    SearchManager searchManager;}

sets the layout

Inject another widget or “view”

specify a resource id (it is optional)

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Beyond Dependency Injection

• Android Annotations(http://code.google.com/p/androidannotations/)

@EActivity(R.layout.myactivity) public class MyActivity extends Activity {     @InjectView     TextView mylabel;     @DrawableRes(R.drawable.myimage)    Drawable image;     @SystemService    SearchManager searchManager;}

sets the layout

Inject another widget or “view”

specify a resource id (it is optional)

Inject objects configured manually

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Beyond Dependency Injection

• Android Annotations(http://code.google.com/p/androidannotations/)

@EActivity(R.layout.myactivity) public class MyActivity extends Activity {     @InjectView     TextView mylabel;     @DrawableRes(R.drawable.myimage)    Drawable image;     @SystemService    SearchManager searchManager;}

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Dependency Injection on Android

• The Android way – android applications all have required access to a single

“Application” class– You can override the Application class– Thus, instant singleton!

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Dependency Injection on Android

• The Android way public class MainApplication extends Application  {     private MyService service;     @Override    public void onCreate() {        super.onCreate();        service = new MyServiceImpl();    }     public MyService getMyService() {        return this.service;    }}

extend the Application

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Dependency Injection on Android

• The Android way public class MainApplication extends Application  {     private MyService service;     @Override    public void onCreate() {        super.onCreate();        service = new MyServiceImpl();    }     public MyService getMyService() {        return this.service;    }}

register your global singleton services

extend the Application

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Dependency Injection on Android

• The Android way public class MainApplication extends Application  {     private MyService service;     @Override    public void onCreate() {        super.onCreate();        service = new MyServiceImpl();    }     public MyService getMyService() {        return this.service;    }}

public class MainActivity extends Activity  {     private MyService service;     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        MainApplication app = (MainApplication) getApplication();        service = app.getMyService();    }}

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Dependency Injection on Android

• The Android way

get a pointer to the Application

public class MainActivity extends Activity  {     private MyService service;     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        MainApplication app = (MainApplication) getApplication();        service = app.getMyService();    }}

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Dependency Injection on Android

• The Android way

access your service

get a pointer to the Application

public class MainActivity extends Activity  {     private MyService service;     @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        MainApplication app = (MainApplication) getApplication();        service = app.getMyService();    }}

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Dependency Injection on Android

• The Android way

Additional Resources

• Project Home– http://www.springsource.org/spring-android– http://www.springsource.org/spring-mobile

• Sample Code– https://github.com/SpringSource/spring-android-samples.git– https://github.com/SpringSource/spring-mobile-samples.git

• Blog Posts– http://blog.springsource.org

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Q&A

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