android NFC开发实例

对于Android 4.0 SDK中提供的Beam例子，对于NFC开发来说的确是一个不错的模板。对于了解NFC的NDEF消息处理过程不妨看下面的代码。

public class Beam extends Activity implements CreateNdefMessageCallback,
OnNdefPushCompleteCallback {
NfcAdapter mNfcAdapter;
TextView mInfoText;
private static final int MESSAGE_SENT = 1;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

mInfoText = (TextView) findViewById(R.id.textView);

mNfcAdapter = NfcAdapter.getDefaultAdapter(this); //实例化NFC设备
if (mNfcAdapter == null) {
mInfoText = (TextView) findViewById(R.id.textView);
mInfoText.setText("NFC is not available on this device.");
}

mNfcAdapter.setNdefPushMessageCallback(this, this); //注册NDEF回调消息
mNfcAdapter.setOnNdefPushCompleteCallback(this, this);
}

@Override
public NdefMessage createNdefMessage(NfcEvent event) {
Time time = new Time();
time.setToNow();
String text = ("Beam me up!\n\n" +
"Beam Time: " + time.format("%H:%M:%S"));
NdefMessage msg = new NdefMessage(
new NdefRecord[] { createMimeRecord(
"application/com.example.android.beam", text.getBytes())
});
return msg;
}

@Override
public void onNdefPushComplete(NfcEvent arg0) {
// A handler is needed to send messages to the activity when this
// callback occurs, because it happens from a binder thread
mHandler.obtainMessage(MESSAGE_SENT).sendToTarget();
}

private final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MESSAGE_SENT:
Toast.makeText(getApplicationContext(), "Message sent!", Toast.LENGTH_LONG).show();
break;
}
}
};

@Override
public void onResume() {
super.onResume();
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {
processIntent(getIntent());
}
}

@Override
public void onNewIntent(Intent intent) {
// onResume gets called after this to handle the intent
setIntent(intent);
}

/**
* Parses the NDEF Message from the intent and prints to the TextView
*/
void processIntent(Intent intent) {
Parcelable[] rawMsgs = intent.getParcelableArrayExtra(
NfcAdapter.EXTRA_NDEF_MESSAGES);
// only one message sent during the beam
NdefMessage msg = (NdefMessage) rawMsgs[0];
// record 0 contains the MIME type, record 1 is the AAR, if present
mInfoText.setText(new String(msg.getRecords()[0].getPayload()));
}

/**
* Creates a custom MIME type encapsulated in an NDEF record
*
* @param mimeType
*/
public NdefRecord createMimeRecord(String mimeType, byte[] payload) {
byte[] mimeBytes = mimeType.getBytes(Charset.forName("US-ASCII"));
NdefRecord mimeRecord = new NdefRecord(
NdefRecord.TNF_MIME_MEDIA, mimeBytes, new byte[0], payload);
return mimeRecord;
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// If NFC is not available, we won't be needing this menu
if (mNfcAdapter == null) {
return super.onCreateOptionsMenu(menu);
}
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.options, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_settings:
Intent intent = new Intent(Settings.ACTION_NFCSHARING_SETTINGS);
startActivity(intent);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}