Book Image

Near Field Communication with Android Cookbook

By : Subtil
Book Image

Near Field Communication with Android Cookbook

By: Subtil

Overview of this book

An easy-to-follow guide, full of hands-on examples of and real-world applications. Each recipe is explained and placed in context. If you want to learn how to create NFC-enabled Android applications, this is the book for you. Perhaps you already know a bit about Android application developments but have never used NFC, or perhaps you know a little about NFC android development but want some more advanced features and examples. In either case, this book will get you up and running quickly. You are expected to have Android programming knowledge.

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Near Field Communication with Android Cookbook
Subtil
Jun, 2014 | 286 pages
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Table of Contents (12 chapters)
Preface
Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Free Chapter
1
1. Getting Started with NFC
1. Getting Started with NFC
Introduction
Requesting NFC permissions
Indicating that your app uses NFC
Defining minimal requirements
Verifying whether the device has an NFC adapter
Downloading Open NFC Android Edition
Downloading Open NFC SDK Edition
Configuring the Open NFC Android add-on into your Android SDK
Configuring an NFC-enabled testing AVD
Configuring the Connection Center tool
Testing your app all together
2
2. Detecting a Tag
2. Detecting a Tag
Introduction
Understanding the foreground dispatch system
Understanding the tag dispatch system
Verifying if your app started because of an NFC intent
Filtering tags by their content type
Filtering tags by their content type programmatically
Filtering tags by their technology
Filtering tags by their technology using programs
Filtering URI tags
3
3. Writing Tag Content
3. Writing Tag Content
Introduction
Working with the NDEF record
Writing a URI-formatted record
Writing a text-formatted record
Using Android Application Record
Working with external types
Working with custom mimes
4
4. Writing Tag Content – Real-life Examples
4. Writing Tag Content – Real-life Examples
Introduction
Making a phone call with one tap – Part 1
Sending a predefined SMS – Part 1
Visiting our website
Leaving a (small) note – Part 1
5
5. Reading Tag Content
5. Reading Tag Content
Introduction
Obtaining NDEF Message from Intent
Getting the data out of the message
Reading a text-formatted record
Reading a URI-formatted record
Reading external types
Reading custom mimes
6
6. Reading Tag Content – Real-life Examples
6. Reading Tag Content – Real-life Examples
Introduction
Making a phone call with one tap – Part 2
Sending a predefined SMS – Part 2
Leaving a (small) note – Part 2
Getting the tag information
7
7. Sharing Content across Devices
7. Sharing Content across Devices
Introduction
Creating a basic peer-to-peer Hello World application
Sending texts to other devices
Sending a friend invite on Facebook
Inviting a friend to play a game – Part 1
8
8. Error Handling and Content Validation
8. Error Handling and Content Validation
Introduction
Handling tag-writing errors
Handling tag-reading errors
Testing the tag data for integrity
9
9. Extending NFC
9. Extending NFC
Introduction
Turning other adapters on/off
Configuring a Wi-Fi network
Starting a Wi-Fi hotspot
Inviting a friend to play a game – Part 2
Controlling hotel room access with Arduino and NFC – Part 1
Controlling hotel room access with Arduino and NFC – Part 2
10
10. Real-life Examples – NFC Utilities
10. Real-life Examples – NFC Utilities
Introduction
Creating multi-action tags
Choosing the best format for our data
Locking tags
Joking with a friend
11
Index
Index

Testing the tag data for integrity

In this recipe, we will create a simple project to demonstrate a simple way to test for data integrity using and MD5 hash.

Getting ready

We will be using the project from the previous recipe, so make sure you have gone through it.

How to do it...

In this application, we will be adding an additional NdefRecord instance into our NdefMessage, which contains the MD5 hash of the main message that will allow us to test for data integrity. Perform the following steps:

  1. Open the project files from the Handling tag-reading errors recipe.

  2. Implement the getMd5Hash method in the NfcHelper class:

      private byte[] getMd5Hash(byte[] message) {

    byte[] salt = "nfcbook.ch8.example3".getBytes(Charset.forName("US-ASCII"));

    try {

      MessageDigest md = MessageDigest.getInstance("MD5");

      ByteArrayOutputStream stream = new ByteArrayOutputStream();

      stream.write(message);
      stream.write(salt);

      return md.digest(stream.toByteArray());

    } catch (Exception...
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