如何将NDEF记录写入NFC标签？

Question

如何将NDEF消息写入NFC标记？我必须更改清单文件吗？到目前为止，我有生成NDEF消息的代码：

    public NdefRecord createTextRecord(String payload, Locale locale, boolean encodeInUtf8) {
    byte[] langBytes = locale.getLanguage().getBytes(Charset.forName("US-ASCII"));
    Charset utfEncoding = encodeInUtf8 ? Charset.forName("UTF-8") : Charset.forName("UTF-16");
    byte[] textBytes = payload.getBytes(utfEncoding);
    int utfBit = encodeInUtf8 ? 0 : (1 << 7);
    char status = (char) (utfBit + langBytes.length);
    byte[] data = new byte[1 + langBytes.length + textBytes.length];
    data[0] = (byte) status;
    System.arraycopy(langBytes, 0, data, 1, langBytes.length);
    System.arraycopy(textBytes, 0, data, 1 + langBytes.length, textBytes.length);
    NdefRecord record = new NdefRecord(NdefRecord.TNF_WELL_KNOWN,
            NdefRecord.RTD_TEXT, new byte[0], data);
    return record;
}

如何发现标签？有人能帮我吗？

Answer 1

我会忽略谷歌文档中的内容，以便在https://developer.android.com/guide/topics/connectivity/nfc/nfc和用于在https://developer.android.com/guide/topics/connectivity/nfc/advanced-nfc#read-写入，因为这提供了非常糟糕的用户写入标签的体验，并且由于用户行为导致大量写入失败。

要获得可靠的写入NFC与Android你应该使用更新和更好的enableReaderModeAPIhttps://developer.android.com/reference/android/nfc/NfcAdapter

使用这个较新的API可以减少失败的写入和损坏的卡，因为您可以控制通知声音发生的时间。使用旧的基于Intent的系统，系统应用程序暂停您的应用程序，然后读取卡并发出通知声音，然后用户在应用程序恢复之前使用卡的方式，并有机会处理卡数据并写入卡片。

使用较新的enableReaderModeAPI，您可以关闭系统通知声音，并且您的应用程序不会暂停以读取NFC卡，然后您可以读取和写入该卡，当您成功写入该卡时，您可以自己发出通知声音。

由于任何错误都是无声的，因此用户将继续尝试出示卡，直到收到成功通知。不需要额外的逻辑来在每次显示一张卡或不同的卡时写入相同的消息。

一些示例代码（改编自我的应用程序NFC低级别读写（不是Ndef Tag技术））

public class NFCActivity extends AppCompatActivity implements NfcAdapter.ReaderCallback{

private NfcAdapter mNfcAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_nfc);

        mNfcAdapter = NfcAdapter.getDefaultAdapter(this);

        // Rest of Activity setup
     }

@Override
    protected void onResume() {
        super.onResume();

        if(mNfcAdapter!= null) {
            Bundle options = new Bundle();
            // Work around for some broken Nfc firmware implementations that poll the card too fast
            options.putInt(NfcAdapter.EXTRA_READER_PRESENCE_CHECK_DELAY, 250);

            // Enable ReaderMode for all types of card and disable platform sounds
            mNfcAdapter.enableReaderMode(this,
                    this,
                    NfcAdapter.FLAG_READER_NFC_A |
                            NfcAdapter.FLAG_READER_NFC_B |
                            NfcAdapter.FLAG_READER_NFC_F |
                            NfcAdapter.FLAG_READER_NFC_V |
                            NfcAdapter.FLAG_READER_NFC_BARCODE |
                            NfcAdapter.FLAG_READER_NO_PLATFORM_SOUNDS,
                    options);
        }

    }

    @Override
    protected void onPause() {
        super.onPause();
        if(mNfcAdapter!= null)
            mNfcAdapter.disableReaderMode(this);
    }
    
   // This method is run in another thread when a card is discovered
   // !!!! This method cannot cannot direct interact with the UI Thread
   // Use `runOnUiThread` method to change the UI from this method
   public void onTagDiscovered(Tag tag) {

      // Read and or write to Tag here to the appropriate Tag Technology type class
      // in this example the card should be an Ndef Technology Type 
      Ndef mNdef = Ndef.get(tag);

      // Check that it is an Ndef capable card
      if (mNdef!= null) {

      // If we want to read
      // As we did not turn on the NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK
      // We can get the cached Ndef message the system read for us.

      NdefMessage mNdefMessage = mNdef.getCachedNdefMessage();


      // Or if we want to write a Ndef message

      // Create a Ndef Record
      NdefRecord mRecord = NdefRecord.createTextRecord("en","English String");

      // Add to a NdefMessage
      NdefMessage mMsg = new NdefMessage(mRecord);
      
      // Catch errors
      try {
          mNdef.connect();
          mNdef.writeNdefMessage(mMsg);

          // Success if got to here
          runOnUiThread(() -> {
             Toast.makeText(getApplicationContext(),
               "Write to NFC Success",
               Toast.LENGTH_SHORT).show();
          });

          // Make a Sound
          try {
              Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
              Ringtone r = RingtoneManager.getRingtone(getApplicationContext(),
                  notification);
              r.play();
              } catch (Exception e) {
                 // Some error playing sound
              }
          
      } catch (FormatException e) {
        // if the NDEF Message to write is malformed
      } catch (TagLostException e) {
        // Tag went out of range before operations were complete
      } catch (IOException e){
        // if there is an I/O failure, or the operation is cancelled
      } finally {
        // Be nice and try and close the tag to
        // Disable I/O operations to the tag from this TagTechnology object, and release resources. 
         try {
                mNdef.close();
             } catch (IOException e) {
               // if there is an I/O failure, or the operation is cancelled
             }
      }

   }

}