Professional Android 4 Application Development

Near Field Communication x 697
Introducing Android Beam
Android Beam, introduced in Android 4.0 (API level 14), provides a simple API for an application to
transmit data between two devices using NFC, simply by placing them back-to-back. For example,
the native contacts, browser, and YouTube applications use Android Beam to share the currently
viewed contact, web page, and video, respectively, with other devices.
To beam messages, your application must be in the foreground and the device
receiving the data must not be locked.
Android Beam is initiated by tapping two NFC-enabled Android devices
together. Users are presented with a “touch to beam” UI, at which point they
can choose to “beam” the foreground application to the other device.
Android Beam uses NFC to push NDEF messages between devices when they are physically placed
together.
By enabling Android Beam within your application, you can define the payload of the beamed
message. If you don’t customize the message, the default action for your application will be to
launch it on the target device. If your application isn’t installed on the target device, the Google Play
Store will launch and display your application’s details page.
To define the message your application beams, you need to request the NFC permission in the
manifest:
The process to define your own custom payload is described as follows:
1. Create an NdefMessage object that contains an NdefRecord that contains your message
payload.
2. Assign your Ndef Message to the NFC Adapter as your Android Beam payload.
3. Configure your application to listen for incoming Android Beam messages.
Creating Android Beam Messages
To create a new Ndef Message, create a new NdefMessage object that contains at least one
NdefRecord containing the payload you want to beam to your application on the target device.
When creating a new Ndef Record, you must specify the type of record it represents, a MIME
type, an ID, and a payload. There are several common types of Ndef Record that can be used to
transmit data using Android Beam; note that they should always be the first record added to each
beamed message.