Android NFC framework introduction and develop guide(6)

Android system NFC framework introduction and develop guide

1. Try to start an Activity with the intent that was created by the tag dispatch system when

parsing the NFC tag (either ACTION_NDEF_DISCOVERED or ACTION_TECH_DISCOVERED).

2. If no activities filter for that intent, try to start an Activity with the next lowest priority intent

(either ACTION_TECH_DISCOVERED or ACTION_TAG_DISCOVERED) until an application filters for the intent or until the tag dispatch system tries all possible intents.

3. If no applications filter for any of the intents, do nothing.

Figure 1. Tag Dispatch System

Whenever possible, work with NDEF messages and the ACTION_NDEF_DISCOVERED intent, because it is the most specific out of the three. This intent allows you to start your application at a more appropriate time than the other two intents, giving the user a better experience. Requesting NFC Access in the Android Manifest

Before you can access a device's NFC hardware and properly handle NFC intents, declare these items in your AndroidManifest.xml file:

The NFC <uses-permission> element to access the NFC hardware:

The minimum SDK version that your application can support. API level 9 only supports

limited tag dispatch via ACTION_TAG_DISCOVERED, and only gives access to NDEF

messages via the EXTRA_NDEF_MESSAGES extra. No other tag properties or I/O