Android NFC
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This document provides an overview of using NFC (Near Field Communication) on Android devices. It discusses registering an NFC intent filter in the manifest to listen for NDEF tags, handling foreground NFC dispatch, interacting with tags using the NfcAdapter class, and reading the payload of NDEF tags which can contain text, URIs, or other data. Future posts will describe extracting specific information from different tag types.
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![Filtering with intents works if our app is not in foreground. If our app is running in foreground, it won't be
notified, if move our smart phone near a NFC tag. In this case we have to use a different technique called
NFC Foreground dispatch. The first step is defining in our code the intent filter (as we did in the
manifest.xml):
Now we have to register our filter, and we do it in onResume method, in this way:
We should, also, remember to disable foreground dispatch as soon as the app gets in background and the
best place to do it is in onPause method.
where nfcAdpt is the NFC Adapter.
Handle NFC Using NFCAdapterHandle NFC Using NFCAdapter
Once we created our filters, we have to interact with the NFC component in our smart phone. For this
purpose, we use NfcAdapter, provided by Android SDK. Using this class, we can check, for example, if the
NFC is supported by our smart phone or if the NFC is turned on or off:
NFC Data: PayloadNFC Data: Payload
Once we know how to handle NFC tag, we want to read the tag content. There are several type of content
defined in NFC specs:
NFC Forum well-known type
Media-type
Absolute URI
NFC Forum external type
Each type has it is own payload. Generally speaking, a NFC NDEF data is composed by a Message. A message
can contain one or more records. Each record is made by an header and a payload (the real information).
By now, if we want to read the data inside a NFC NDEF tag we can use:
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@Override
protected void onCreate(Bundle savedInstanceState) {
...
Intent nfcIntent = new Intent(this, getClass());
nfcIntent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
nfcPendingIntent =
PendingIntent.getActivity(this, 0, nfcIntent, 0);
IntentFilter tagIntentFilter =
new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
try {
tagIntentFilter.addDataType("text/plain");
intentFiltersArray = new IntentFilter[]{tagIntentFilter};
}
catch (Throwable t) {
t.printStackTrace();
}
}
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protected void onResume() {
super.onResume();
nfcAdpt.enableForegroundDispatch(
this,
nfcPendingIntent,
intentFiltersArray,
null);
handleIntent(getIntent());
}
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@Override
protected void onPause() {
super.onPause();
nfcAdpt.disableForegroundDispatch(this);
}
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@Override
protected void onCreate(Bundle savedInstanceState) {
...
nfcAdpt = NfcAdapter.getDefaultAdapter(this);
// Check if the smartphone has NFC
if (nfcAdpt == null) {
Toast.makeText(this, "NFC not supported", Toast.LENGTH_LONG).show();
finish();
}
// Check if NFC is enabled
if (!nfcAdpt.isEnabled()) {
Toast.makeText(this, "Enable NFC before using the app", Toast.LENGTH_LONG).show();
}
}
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Android NFC
- 1. Topics covered NFCNFC NDEFNDEF NFC Foreground dispatchNFC Foreground dispatch NFC payloadNFC payload NFC filterNFC filter Home » androd » ndef » nfc » tag » First steps with NFC in Android FIRST STEPS WITH NFC IN ANDROID PUBBLICATO DA FRANCESCO AZZOLA IN ANDROD, NDEF, NFC, TAG - ON MARCH 8, 2015 - NO COMMENTS This post describes how to use NFC in Android. The NFC technology stands for Near Field Communication and you can find the specification at NFC Forum. In this first post, we will analyse some basic aspects of NFC and we will describe how we can implement an app in Android that handles NFC tags. If you want to experiment NFC, there are several web site where you can buy NFC with a few euro. NFC can be used in different situation: we can use it to turn on our Wifi when we are at home or launch task actions and so on. We will focus our attention on NDEF data that is a special type of NFC tag. There are some basic steps we have to follow before using the NFC. NFC FilterNFC Filter When we use NFC tag,, the first thing we want is our app is notified when we get near a NFC tag. To this purpose we use a intent filter. Android SDK provides three different filter that we can use with different level of priority: ACTION_NDEF_DISCOVERED ACTION_TECH_DISCOVERED ACTION_TAG_DISCOVERED We focus our attention on ACTION_NDEF_DISCOVERED, that has the highest level of priority. As said, our goal is being notified when the smart phone is near a NFC tag and, if we have only this app installed and capable to handle this NFC tag, we want that the app starts immediately. To do it, we register the filter in the Manifest.xml: At line 6 we register our app so that it can be notified with ACTION_NDEF_DISCOVERED. We can use different types of filter, in this example (at line 8) we used mime type. In other word when a NFC tag NDEF is discovered and it has a mime type text/plain then our app will be started. We can filter using several mime types not only text/pain. We can, moreover, use other type of filters like android:scheme to filter using the protocol or using a string pattern. NFC Foreground DispatchNFC Foreground Dispatch 28 2LikeLike 1 2 3 4 5 6 7 8 9 10 <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.survivingwithandroid.nfc" > .... <intent-filter> <action android:name="android.nfc.action.NDEF_DISCOVERED" /> <category android:name="android.intent.category.DEFAULT" /> <data android:mimeType="text/plain"/> </intent-filter> <manifest> ? SURVIVING W/ ANDROID ANDROID DEVELOPMENT BLOG TUTORIALS ABOUT ANDROID DEV TOPICS Search here....! " # + %
- 2. Filtering with intents works if our app is not in foreground. If our app is running in foreground, it won't be notified, if move our smart phone near a NFC tag. In this case we have to use a different technique called NFC Foreground dispatch. The first step is defining in our code the intent filter (as we did in the manifest.xml): Now we have to register our filter, and we do it in onResume method, in this way: We should, also, remember to disable foreground dispatch as soon as the app gets in background and the best place to do it is in onPause method. where nfcAdpt is the NFC Adapter. Handle NFC Using NFCAdapterHandle NFC Using NFCAdapter Once we created our filters, we have to interact with the NFC component in our smart phone. For this purpose, we use NfcAdapter, provided by Android SDK. Using this class, we can check, for example, if the NFC is supported by our smart phone or if the NFC is turned on or off: NFC Data: PayloadNFC Data: Payload Once we know how to handle NFC tag, we want to read the tag content. There are several type of content defined in NFC specs: NFC Forum well-known type Media-type Absolute URI NFC Forum external type Each type has it is own payload. Generally speaking, a NFC NDEF data is composed by a Message. A message can contain one or more records. Each record is made by an header and a payload (the real information). By now, if we want to read the data inside a NFC NDEF tag we can use: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 @Override protected void onCreate(Bundle savedInstanceState) { ... Intent nfcIntent = new Intent(this, getClass()); nfcIntent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP); nfcPendingIntent = PendingIntent.getActivity(this, 0, nfcIntent, 0); IntentFilter tagIntentFilter = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED); try { tagIntentFilter.addDataType("text/plain"); intentFiltersArray = new IntentFilter[]{tagIntentFilter}; } catch (Throwable t) { t.printStackTrace(); } } 1 2 3 4 5 6 7 8 9 protected void onResume() { super.onResume(); nfcAdpt.enableForegroundDispatch( this, nfcPendingIntent, intentFiltersArray, null); handleIntent(getIntent()); } 1 2 3 4 5 @Override protected void onPause() { super.onPause(); nfcAdpt.disableForegroundDispatch(this); } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 @Override protected void onCreate(Bundle savedInstanceState) { ... nfcAdpt = NfcAdapter.getDefaultAdapter(this); // Check if the smartphone has NFC if (nfcAdpt == null) { Toast.makeText(this, "NFC not supported", Toast.LENGTH_LONG).show(); finish(); } // Check if NFC is enabled if (!nfcAdpt.isEnabled()) { Toast.makeText(this, "Enable NFC before using the app", Toast.LENGTH_LONG).show(); } } ? ? ? ?
- 3. Android Text to Speech (TTS) NFC Android: Read NDEF Tag Android Text to Speech (TTS) NFC Android: Read NDEF Tag RELATED POSTS : RELATED POSTS : In the next post, we will describe how to read different NDEF types and how to extract information from the tag. If you want to know how to read look at NFC - Read NDEF Tag. ETICHETTE: ANDROD, NDEF, NFC, TAG 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 @Override public void onNewIntent(Intent intent) { Log.d("Nfc", "New intent"); getTag(intent); } private void getTag(Intent i) { if (i == null) return ; String type = i.getType(); String action = i.getAction(); List<ndefdata> dataList = new ArrayList<ndefdata>(); if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)) { Log.d("Nfc", "Action NDEF Found"); Parcelable[] parcs = i.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES); for (Parcelable p : parcs) { recNumberTxt.setText(String.valueOf(numRec)); NdefRecord[] records = msg.getRecords(); for (NdefRecord record: records) { short tnf = record.getTnf(); // Here we handle the payload } } } } </ndefdata></ndefdata> 227 66Google + 1 26DZone 106Reddit 1 ?
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