Native Android Development Practices

Transcription

1 Native Android Development Practices Roy Clarkson & Josh Long SpringSource, a division of VMware 1

2 About Roy Clarkson (Spring Android 2

3 About Roy Clarkson (Spring Android 2

4 About Roy Clarkson (Spring Android 2

5 About Josh Long (Spring Developer 3

6 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 4

7 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 5

8 Device Detection Demo 6

9 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 7

10 Site Preference Demo 8

11 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 9

12 Site Switcher Demo 10

13 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 11

14 Agenda 12

15 Agenda 12

16 Agenda 12

17 An Introduction to Android! More than 500,000 activations every day 13

18 An Introduction to Android! Huge and growing ecosystem of applications and a market to boot Expected downloads in 2011 Android Market Place Apple App Store 8.1 billion app downloads 6 billion * 14

19 Easy to get started Programs are written in Java ( ) 15

20 Easy to get started Programs are written in Java ( ) 15

21 Easy to get started Programs are written in Java ( ) 15

22 Easy APIs and concepts no real applications, only loosely coupled components Activities Services Content Providers Broadcast Receivers describes the unit of work for one screen does background work like synchronization with a cloud service component that knows how to render and manipulate content of a certain type knows how to receive and respond to system-wide events like screen shutoff. * 16

23 A Simple Activity package org.springframework.android.activities; import android.app.activity; import android.os.bundle; public class HelloAndroid extends Activity { public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.main); } 17

24 A Simple Activity package org.springframework.android.activities; import android.app.activity; import android.os.bundle; You *must* extend Android classes to build proper components public class HelloAndroid extends Activity { public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.main); } 17

25 A Simple Activity package org.springframework.android.activities; import android.app.activity; import android.os.bundle; You *must* extend Android classes to build proper components public class HelloAndroid extends Activity public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.main); } R.* refers to constants that Android code generates for you that correspond to resources } 17

26 Declaring the Simple Activity /res/values/strings.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/layout/main.xml <?xml version="1.0" encoding="utf-8"?> <TextView xmlns:android=" android:id="@+id/textview" android:layout_width="fill_parent" android:layout_height="fill_parent" android:text="@string/hello"/> 18

27 Lifecycle Android controls lifecycles of these components Registered in manifest <activity android:name=".activities.helloandroid <intent-filter> <action android:name="android.intent.action.main" /> <category android:name="android.intent.category.launcher" /> </intent-filter> </activity> 19

28 Lifecycle Android controls lifecycles of these components Registered in manifest Class is set relative to root package specified in manifest <activity android:name=".activities.helloandroid <intent-filter> <action android:name="android.intent.action.main" /> <category android:name="android.intent.category.launcher" /> </intent-filter> </activity> 19

29 Lifecycle Android controls lifecycles of these components Registered in manifest Class is set relative to root package specified in manifest <activity android:name=".activities.helloandroid <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 19

30 Android Sample Demo How to use STS and the Android Eclipse plugin 20

31 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 Maven Android SDK Deployer If you need to use Google maps, then you have to go this route Maven Android Plugin Provides support for Maven dependency management within Android projects 21

32 Maven Android Plugin Configuration <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> 22

33 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 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

34 Running the simple Activity 24

35 Running the simple Activity 24

36 ...what about something a bit more non-trivial? 25

37 Enter Spring Android! Spring s aim: bring simplicity to java development modern web data access integration mobile social security the cloud: CloudFoundry Google App Engine Amazon Web Services BeanStalk Heroku The Spring framework lightweight tc Server Tomcat Jetty traditional WebSphere JBoss AS WebLogic (on legacy versions, too!) 26

38 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. 27

39 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 28

40 Basic Rest Template Example Google search example RestTemplate resttemplate = new RestTemplate(); String url = " String result = resttemplate.getforobject(url, String.class, "SpringSource"); Multiple parameters RestTemplate resttemplate = new RestTemplate(); String url = " String result = resttemplate.getforobject(url, String.class, "42", 21 ); 29

41 Demo Using Spring Android to communicate with a RESTful web service (Google Search Demo) 30

42 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(...) 31

43 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 32

44 Spring Android Showcase Examples HTTP GET JSON XML HTTP GET with Parameters JSON XML HTTP POST String JSON XML MultiValueMap HTTP and GZIP 33

45 Spring Android Demos Spring Android Showcase Demo 34

46 Spring Social on Android Supports connecting to supported Spring Social services uses same RESTful connectivity based on RestTemplate 35

47 Enter Spring Android! 36

48 do NOT reinvent the Wheel! 37

49 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 38

50 Dependency Injection on Android Lots of options RoboGuice Android Annotations the Android way 39

51 Dependency Injection on Android 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!) 40

52 Dependency Injection on Android RoboGuice ( before RoboGuice public class MyActivity extends Activity { private TextView label; private Drawable image; private SearchManager searchmanager; 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) } 41

53 Dependency Injection on Android RoboGuice ( 41

54 Dependency Injection on Android RoboGuice ( with RoboGuice public class MyActivity extends RoboActivity TextView Drawable SearchManager searchmanager; public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.myactivity); } 41

55 Dependency Injection on Android RoboGuice ( with RoboGuice public class MyActivity extends RoboActivity TextView label; used to inject other widgets or Drawable SearchManager searchmanager; public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.myactivity); } 41

56 Dependency Injection on Android RoboGuice ( with RoboGuice public class MyActivity extends RoboActivity TextView Drawable image; used to inject other widgets or views used to inject SearchManager searchmanager; public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.myactivity); } 41

57 Dependency Injection on Android RoboGuice ( with RoboGuice public class MyActivity extends RoboActivity TextView Drawable SearchManager searchmanager; used to inject other widgets or views used to inject Resources used to inject other objects public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.myactivity); } 41

58 Dependency Injection on Android 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 42

59 Beyond Dependency Injection Android Annotations ( 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 43

60 Beyond Dependency Injection Android Annotations public class MyActivity extends Activity TextView Drawable image; SearchManager searchmanager; 44

61 Beyond Dependency Injection Android Annotations public class MyActivity extends Activity { sets the TextView Drawable image; SearchManager searchmanager; 44

62 Beyond Dependency Injection Android Annotations public class MyActivity extends Activity TextView mylabel; sets the layout Inject another widget or Drawable image; SearchManager searchmanager; 44

63 Beyond Dependency Injection Android Annotations public class MyActivity extends Activity TextView Drawable image; sets the layout Inject another widget or view specify a resource id (it is optional) SearchManager searchmanager; 44

64 Beyond Dependency Injection Android Annotations public class MyActivity extends Activity TextView Drawable image; sets the layout Inject another widget or view specify a resource id (it is optional) SearchManager searchmanager; Inject objects configured manually 44

65 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! 45

66 Dependency Injection on Android The Android way public class MainApplication extends Application { private MyService public void oncreate() { super.oncreate(); service = new MyServiceImpl(); } } public MyService getmyservice() { return this.service; } 46

67 Dependency Injection on Android The Android way public class MainApplication extends Application { private MyService service; extend the public void oncreate() { super.oncreate(); service = new MyServiceImpl(); } } public MyService getmyservice() { return this.service; } 46

68 Dependency Injection on Android The Android way public class MainApplication extends Application { private MyService public void oncreate() { super.oncreate(); service = new MyServiceImpl(); } extend the Application register your global singleton services } public MyService getmyservice() { return this.service; } 46

69 Dependency Injection on Android The Android way public class MainActivity extends Activity { private MyService service; public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); MainApplication app = (MainApplication) getapplication(); service = app.getmyservice(); } 47

70 Dependency Injection on Android The Android way public class MainActivity extends Activity { } private MyService service; get a pointer to the public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); MainApplication app = (MainApplication) getapplication(); service = app.getmyservice(); } 47

71 Dependency Injection on Android The Android way public class MainActivity extends Activity { } private MyService service; get a pointer to the public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); MainApplication app = (MainApplication) getapplication(); service = app.getmyservice(); } access your service 47

72 Additional Resources Project Home Sample Code Blog Posts 48

73 Q&A SpringOne 2GX All rights reserved. Do not distribute without permission.