Android NFC開發實戰

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

1. public class Beam extends Activity implements CreateNdefMessageCallback,
2. OnNdefPushCompleteCallback {
3. NfcAdapter mNfcAdapter;
4. TextView mInfoText;
5. private static final int MESSAGE_SENT = 1;
7. @Override
8. public void onCreate(Bundle savedInstanceState) {
9. super.onCreate(savedInstanceState);
10. setContentView(R.layout.main);
12. mInfoText = (TextView) findViewById(R.id.textView);
14. mNfcAdapter = NfcAdapter.getDefaultAdapter(this); //實例化NFC設備
15. if (mNfcAdapter == null) {
16. mInfoText = (TextView) findViewById(R.id.textView);
17. mInfoText.setText("NFC is not available on this device.");
18. }
20. mNfcAdapter.setNdefPushMessageCallback(this, this); //注冊NDEF回調消息
21. mNfcAdapter.setOnNdefPushCompleteCallback(this, this);
22. }
25. @Override
26. public NdefMessage createNdefMessage(NfcEvent event) {
27. Time time = new Time();
28. time.setToNow();
29. String text = ("Beam me up!\n\n" +
30. "Beam Time: " + time.format("%H:%M:%S"));
31. NdefMessage msg = new NdefMessage(
32. new NdefRecord[] { createMimeRecord(
33. "application/com.example.android.beam", text.getBytes())
34. });
35. return msg;
36. }
38. @Override
39. public void onNdefPushComplete(NfcEvent arg0) {
40. // A handler is needed to send messages to the activity when this
41. // callback occurs, because it happens from a binder thread
42. mHandler.obtainMessage(MESSAGE_SENT).sendToTarget();
43. }
45. private final Handler mHandler = new Handler() {
46. @Override
47. public void handleMessage(Message msg) {
48. switch (msg.what) {
49. case MESSAGE_SENT:
50. Toast.makeText(getApplicationContext(), "Message sent!", Toast.LENGTH_LONG).show();
51. break;
52. }
53. }
54. };
56. @Override
57. public void onResume() {
58. super.onResume();
59. if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {
60. processIntent(getIntent());
61. }
62. }
64. @Override
65. public void onNewIntent(Intent intent) {
66. // onResume gets called after this to handle the intent
67. setIntent(intent);
68. }
70. /**
71. * Parses the NDEF Message from the intent and prints to the TextView
72. */
73. void processIntent(Intent intent) {
74. Parcelable[] rawMsgs = intent.getParcelableArrayExtra(
75. NfcAdapter.EXTRA_NDEF_MESSAGES);
76. // only one message sent during the beam
77. NdefMessage msg = (NdefMessage) rawMsgs[0];
78. // record 0 contains the MIME type, record 1 is the AAR, if present
79. mInfoText.setText(new String(msg.getRecords()[0].getPayload()));
80. }
82. /**
83. * Creates a custom MIME type encapsulated in an NDEF record
84. *
85. * @param mimeType
86. */
87. public NdefRecord createMimeRecord(String mimeType, byte[] payload) {
88. byte[] mimeBytes = mimeType.getBytes(Charset.forName("US-ASCII"));
89. NdefRecord mimeRecord = new NdefRecord(
90. NdefRecord.TNF_MIME_MEDIA, mimeBytes, new byte[0], payload);
91. return mimeRecord;
92. }
94. @Override
95. public boolean onCreateOptionsMenu(Menu menu) {
96. // If NFC is not available, we won't be needing this menu
97. if (mNfcAdapter == null) {
98. return super.onCreateOptionsMenu(menu);
99. }
100. MenuInflater inflater = getMenuInflater();
101. inflater.inflate(R.menu.options, menu);
102. return true;
103. }
104. @Override
105. public boolean onOptionsItemSelected(MenuItem item) {
106. switch (item.getItemId()) {
107. case R.id.menu_settings:
108. Intent intent = new Intent(Settings.ACTION_NFCSHARING_SETTINGS);
109. startActivity(intent);
110. return true;
111. default:
112. return super.onOptionsItemSelected(item);
113. }
114. }
115. }