android NFC開發實例

對于Android 4.0 SDK中提供的Beam例子，對于NFC開發來說的確是一個不錯的模板。對于了解NFC的NDEF消息處理過程不妨看下面的代碼。

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

    mNfcAdapter.setNdefPushMessageCallback(this, this); //注冊NDEF回調消息
    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);
    }
}

}</pre>