Pro Android Web Apps_ Develop for Android using HTML5, CSS3 and JavaScript [Oehlman & Blanc 2011-02-21].pdf

Pro Android Web Apps: Develop for Android Using HTML5, CSS3 & JavaScript

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ISBN-13 (pbk): 978-1-4302-3276-6

ISBN-13 (electronic): 978-1-4302-3277-3

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Lead Editors: Steve Anglin and Douglas Pundick

Technical Reviewer: Kunal Mittal

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••

Contents

■ Contents at a Glance....................................................................................... iv

■

About the Authors ........................................................................................... x

■ About the Technical Reviewer........................................................................ xi

■

Acknowledgments ......................................................................................... xii

■ Introduction .................................................................................................. xiii

■ Chapter 1: Getting Started ............................................................................... 1

Understanding Android Platform Capabilities ......................................................................................................... 1

Device Connectivity............................................................................................................................................ 2

Touch ................................................................................................................................................................. 3

Geolocation ........................................................................................................................................................ 3

Hardware Sensors ............................................................................................................................................. 4

Local Databases and Storage ............................................................................................................................ 5

Camera Support ................................................................................................................................................. 5

Messaging and Push Notifications..................................................................................................................... 5

WebKit Web Browser ......................................................................................................................................... 6

Process Management ........................................................................................................................................ 6

Android OS Feature Summary ........................................................................................................................... 7

Preparing the Development Environment ............................................................................................................... 8

Text Editors and Working Directories ................................................................................................................ 8

Web Server ........................................................................................................................................................ 9

Emulator .......................................................................................................................................................... 11

Hello World............................................................................................................................................................ 16

Summary .............................................................................................................................................................. 19

■ CONTENTS

■ Chapter 2: Building a Mobile HTML Entry Form............................................. 21

HTML for the Mobile Web ..................................................................................................................................... 21

Mobile-Ready Web Pages ................................................................................................................................ 21

Adding Form Elements..................................................................................................................................... 26

Adding Some Style................................................................................................................................................ 27

Form Styles with a Splash of CSS3.................................................................................................................. 30

Improving the Page Title Appearance .............................................................................................................. 33

Coding for Different Screen Sizes .................................................................................................................... 34

Handling Device Orientation Changes.............................................................................................................. 35

Adding Form Validation......................................................................................................................................... 39

Providing Feedback with Limited Screen Space ............................................................................................. 40

Summary .............................................................................................................................................................. 46

Chapter 3: HTML5 Storage APIs..................................................................... 47

The Web Storage API ............................................................................................................................................ 48

Saving Objects to Web Storage Using JSON .................................................................................................... 49

Local vs. Session Storage ................................................................................................................................ 54

The Web SQL Database......................................................................................................................................... 54

Saving To-Do List Items with a Client-Side Database ..................................................................................... 56

Database Versioning and Upgrades ................................................................................................................. 62

Summary .............................................................................................................................................................. 63

■

Chapter 4: Constructing a Multipage App ..................................................... 65

Single HTML File, Multiple App Pages .................................................................................................................. 65

Creating a View Manager................................................................................................................................. 68

Implementing View Actions ............................................................................................................................. 70

Building the Application’s Main Screen ................................................................................................................ 73

Tweaking ViewManager Functionality ............................................................................................................. 77

Home Screen Storage Requirements............................................................................................................... 78

Wiring Up the Home Screen............................................................................................................................. 82

Building the All Tasks Screen ............................................................................................................................... 85

Implementing the View Stack ............................................................................................................................... 91

Summary .............................................................................................................................................................. 94

■ Chapter 5: Synchronizing with the Cloud ...................................................... 95

Exploring Online Storage Options ......................................................................................................................... 95

Online Synchronization Store Requirements ................................................................................................... 96

Avoiding a Three-Tier Architecture .................................................................................................................. 96

User Authentication ......................................................................................................................................... 96

A JavaScript Synchronization Library .............................................................................................................. 97

Possible Synchronization Solutions ................................................................................................................. 97

Getting Started with Google App Engine............................................................................................................... 98

Deploying jsonengine Locally .......................................................................................................................... 99

Choosing a Suitable Synchronization Mode................................................................................................... 100

Sending Your Offline Data to jsonengine ....................................................................................................... 101

Updating the User Interface for Online Synchronization ..................................................................................... 103

Making a Desktop Interface ................................................................................................................................ 106

Querying a jsonengine Instance..................................................................................................................... 107

Deploying Your Application on the Cloud ....................................................................................................... 109

Summary ............................................................................................................................................................ 110

■

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