Leyendo NFC Tags con Android

  <uses-sdk

		android:minSdkVersion="10"

        android:targetSdkVersion="17" />

	<TextView

        android:id="@+id/textView_explanation"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="@string/explanation" />

	<uses-permission android:name="android.permission.NFC" />

    <uses-feature

        android:name="android.hardware.nfc"

        android:required="true" />

	package net.vrallev.android.nfc.demo;

	import android.app.Activity;

	import android.nfc.NfcAdapter;

	import android.os.Bundle;

	import android.widget.TextView;

	import android.widget.Toast;

	/**

	 * Activity for reading data from an NDEF Tag.

	 * 

	 * @author Ralf Wondratschek

	 *

	 */

	public class MainActivity extends Activity {

		public static final String TAG = "NfcDemo";

		private TextView mTextView;

		private NfcAdapter mNfcAdapter;

		@Override

		protected void onCreate(Bundle savedInstanceState) {

			super.onCreate(savedInstanceState);

			setContentView(R.layout.activity_main);

			mTextView = (TextView) findViewById(R.id.textView_explanation);

			mNfcAdapter = NfcAdapter.getDefaultAdapter(this);

			if (mNfcAdapter == null) {

				// Stop here, we definitely need NFC

				Toast.makeText(this, "This device doesn't support NFC.", Toast.LENGTH_LONG).show();

				finish();

				return;

			}

			if (!mNfcAdapter.isEnabled()) {

				mTextView.setText("NFC is disabled.");

			} else {

				mTextView.setText(R.string.explanation);

			}

			handleIntent(getIntent());

		}

		private void handleIntent(Intent intent) {

			// TODO: handle Intent

		}

	}

	<intent-filter>

		<action android:name="android.nfc.action.NDEF_DISCOVERED" />

		<category android:name="android.intent.category.DEFAULT" />

		<data android:mimeType="text/plain" />

	</intent-filter>

	package net.vrallev.android.nfc.demo;

	import android.app.Activity;

	import android.app.PendingIntent;

	import android.content.Intent;

	import android.content.IntentFilter;

	import android.content.IntentFilter.MalformedMimeTypeException;

	import android.nfc.NfcAdapter;

	import android.os.Bundle;

	import android.widget.TextView;

	import android.widget.Toast;

	/**

	 * Activity for reading data from an NDEF Tag.

	 * 

	 * @author Ralf Wondratschek

	 *

	 */

	public class MainActivity extends Activity {

		public static final String MIME_TEXT_PLAIN = "text/plain";

		public static final String TAG = "NfcDemo";

		private TextView mTextView;

		private NfcAdapter mNfcAdapter;

		@Override

		protected void onCreate(Bundle savedInstanceState) {

			super.onCreate(savedInstanceState);

			setContentView(R.layout.activity_main);

			mTextView = (TextView) findViewById(R.id.textView_explanation);

			mNfcAdapter = NfcAdapter.getDefaultAdapter(this);

			if (mNfcAdapter == null) {

				// Stop here, we definitely need NFC

				Toast.makeText(this, "This device doesn't support NFC.", Toast.LENGTH_LONG).show();

				finish();

				return;

			}

			if (!mNfcAdapter.isEnabled()) {

				mTextView.setText("NFC is disabled.");

			} else {

				mTextView.setText(R.string.explanation);

			}

			handleIntent(getIntent());

		}

		@Override

		protected void onResume() {

			super.onResume();

			/**

			 * It's important, that the activity is in the foreground (resumed). Otherwise

			 * an IllegalStateException is thrown. 

			 */

			setupForegroundDispatch(this, mNfcAdapter);

		}

		@Override

		protected void onPause() {

			/**

			 * Call this before onPause, otherwise an IllegalArgumentException is thrown as well.

			 */

			stopForegroundDispatch(this, mNfcAdapter);

			super.onPause();

		}

		@Override

		protected void onNewIntent(Intent intent) { 

			/**

			 * This method gets called, when a new Intent gets associated with the current activity instance.

			 * Instead of creating a new activity, onNewIntent will be called. For more information have a look

			 * at the documentation.

			 * 

			 * In our case this method gets called, when the user attaches a Tag to the device.

			 */

			handleIntent(intent);

		}

		private void handleIntent(Intent intent) {

			// TODO: handle Intent

		}

		/**

		 * @param activity The corresponding {@link Activity} requesting the foreground dispatch.

		 * @param adapter The {@link NfcAdapter} used for the foreground dispatch.

		 */

		public static void setupForegroundDispatch(final Activity activity, NfcAdapter adapter) {

			final Intent intent = new Intent(activity.getApplicationContext(), activity.getClass());

			intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);

			final PendingIntent pendingIntent = PendingIntent.getActivity(activity.getApplicationContext(), 0, intent, 0);

			IntentFilter[] filters = new IntentFilter[1];

			String[][] techList = new String[][]{};

			// Notice that this is the same filter as in our manifest.

			filters[0] = new IntentFilter();

			filters[0].addAction(NfcAdapter.ACTION_NDEF_DISCOVERED);

			filters[0].addCategory(Intent.CATEGORY_DEFAULT);

			try {

				filters[0].addDataType(MIME_TEXT_PLAIN);

			} catch (MalformedMimeTypeException e) {

				throw new RuntimeException("Check your mime type.");

			}

			adapter.enableForegroundDispatch(activity, pendingIntent, filters, techList);

		}

		/**

		 * @param activity The corresponding {@link BaseActivity} requesting to stop the foreground dispatch.

		 * @param adapter The {@link NfcAdapter} used for the foreground dispatch.

		 */

		public static void stopForegroundDispatch(final Activity activity, NfcAdapter adapter) {

			adapter.disableForegroundDispatch(activity);

		}

	}

	package net.vrallev.android.nfc.demo;

	import java.io.UnsupportedEncodingException;

	import java.util.Arrays;

	import android.app.Activity;

	import android.app.PendingIntent;

	import android.content.Intent;

	import android.content.IntentFilter;

	import android.content.IntentFilter.MalformedMimeTypeException;

	import android.nfc.NdefMessage;

	import android.nfc.NdefRecord;

	import android.nfc.NfcAdapter;

	import android.nfc.Tag;

	import android.nfc.tech.Ndef;

	import android.os.AsyncTask;

	import android.os.Bundle;

	import android.util.Log;

	import android.widget.TextView;

	import android.widget.Toast;

	/*

	 * ... other code parts

	 */

	private void handleIntent(Intent intent) {

		String action = intent.getAction();

		if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)) {

			String type = intent.getType();

			if (MIME_TEXT_PLAIN.equals(type)) {

				Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);

				new NdefReaderTask().execute(tag);

			} else {

				Log.d(TAG, "Wrong mime type: " + type);

			}

		} else if (NfcAdapter.ACTION_TECH_DISCOVERED.equals(action)) {

			// In case we would still use the Tech Discovered Intent

			Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);

			String[] techList = tag.getTechList();

			String searchedTech = Ndef.class.getName();

			for (String tech : techList) {

				if (searchedTech.equals(tech)) {

					new NdefReaderTask().execute(tag);

					break;

				}

			}

		}

	}

	/**

	 * Background task for reading the data. Do not block the UI thread while reading. 

	 * 

	 * @author Ralf Wondratschek

	 *

	 */

	private class NdefReaderTask extends AsyncTask<Tag, Void, String> {

		@Override

		protected String doInBackground(Tag... params) {

			Tag tag = params[0];

			Ndef ndef = Ndef.get(tag);

			if (ndef == null) {

				// NDEF is not supported by this Tag. 

				return null;

			}

			NdefMessage ndefMessage = ndef.getCachedNdefMessage();

			NdefRecord[] records = ndefMessage.getRecords();

			for (NdefRecord ndefRecord : records) {

				if (ndefRecord.getTnf() == NdefRecord.TNF_WELL_KNOWN && Arrays.equals(ndefRecord.getType(), NdefRecord.RTD_TEXT)) {

					try {

						return readText(ndefRecord);

					} catch (UnsupportedEncodingException e) {

						Log.e(TAG, "Unsupported Encoding", e);

					}

				}

			}

			return null;

		}

		private String readText(NdefRecord record) throws UnsupportedEncodingException {

			/*

			 * See NFC forum specification for "Text Record Type Definition" at 3.2.1 

			 * 

			 * http://www.nfc-forum.org/specs/

			 * 

			 * bit_7 defines encoding

			 * bit_6 reserved for future use, must be 0

			 * bit_5..0 length of IANA language code

			 */

			byte[] payload = record.getPayload();

			// Get the Text Encoding

			String textEncoding = ((payload[0] & 128) == 0) ? "UTF-8" : "UTF-16";

			// Get the Language Code

			int languageCodeLength = payload[0] & 0063;

			// String languageCode = new String(payload, 1, languageCodeLength, "US-ASCII");

			// e.g. "en"

			// Get the Text

			return new String(payload, languageCodeLength + 1, payload.length - languageCodeLength - 1, textEncoding);

		}

		@Override

		protected void onPostExecute(String result) {

			if (result != null) {

				mTextView.setText("Read content: " + result);

			}

		}

	}