我一直在使用 HCE 并在

isoDep.connect();

在特定的 Android 阅读器设备上 cr100 simcent .

当我使用以下标志在 NFC 中启用阅读器模式时，HCE 工作得非常好。

public static int READER_FLAGS =
        NfcAdapter.FLAG_READER_NFC_A | NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK;

但是我无法读取 NDEF 标签。尽管相同的代码在 Nexus 7 (2012) 平板电脑上运行良好。

附上完整代码

读卡器 fragment

public class CardReaderFragment extends Fragment implements LoyaltyCardReader.AccountCallback {

    public static final String TAG = "CardReaderFragment";
    // Recommend NfcAdapter flags for reading from other Android devices. Indicates that this
    // activity is interested in NFC-A devices (including other Android devices), and that the
    // system should not check for the presence of NDEF-formatted data (e.g. Android Beam).
    public static int READER_FLAGS =
            NfcAdapter.FLAG_READER_NFC_A | NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK;
    public LoyaltyCardReader mLoyaltyCardReader;
    private TextView mAccountField;

    /** Called when sample is created. Displays generic UI with welcome text. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View v = inflater.inflate(R.layout.main_fragment, container, false);
        if (v != null) {
            mAccountField = (TextView) v.findViewById(R.id.card_account_field);
            mAccountField.setText("Waiting...");

            mLoyaltyCardReader = new LoyaltyCardReader(this);

            // Disable Android Beam and register our card reader callback
            enableReaderMode();
        }

        return v;
    }

    @Override
    public void onPause() {
        super.onPause();
        disableReaderMode();
    }

    @Override
    public void onResume() {
        super.onResume();
        enableReaderMode();
    }

    private void enableReaderMode() {
        Log.i(TAG, "Enabling reader mode");
        Activity activity = getActivity();
        NfcAdapter nfc = NfcAdapter.getDefaultAdapter(activity);
        if (nfc != null) {
            nfc.enableReaderMode(activity, mLoyaltyCardReader, READER_FLAGS, null);
        }
    }

    private void disableReaderMode() {
        Log.i(TAG, "Disabling reader mode");
        Activity activity = getActivity();
        NfcAdapter nfc = NfcAdapter.getDefaultAdapter(activity);
        if (nfc != null) {
            nfc.disableReaderMode(activity);
        }
    }

    @Override
    public void onAccountReceived(final String account) {
        // This callback is run on a background thread, but updates to UI elements must be performed
        // on the UI thread.
        getActivity().runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mAccountField.setText(account);
            }
        });
    }
}

忠诚卡阅读器

public class LoyaltyCardReader implements NfcAdapter.ReaderCallback {
    private static final String TAG = "LoyaltyCardReader";
    // AID for our loyalty card service.
    private static final String SAMPLE_LOYALTY_CARD_AID = "F222222222";
    // ISO-DEP command HEADER for selecting an AID.
    // Format: [Class | Instruction | Parameter 1 | Parameter 2]
    private static final String SELECT_APDU_HEADER = "00A40400";
    // "OK" status word sent in response to SELECT AID command (0x9000)
    private static final byte[] SELECT_OK_SW = {(byte) 0x90, (byte) 0x00};

    // Weak reference to prevent retain loop. mAccountCallback is responsible for exiting
    // foreground mode before it becomes invalid (e.g. during onPause() or onStop()).
    private WeakReference<AccountCallback> mAccountCallback;

    public interface AccountCallback {
        public void onAccountReceived(String account);
    }

    public LoyaltyCardReader(AccountCallback accountCallback) {
        mAccountCallback = new WeakReference<AccountCallback>(accountCallback);
    }

    /**
     * Callback when a new tag is discovered by the system.
     * <p>
     * <p>Communication with the card should take place here.
     *
     * @param tag Discovered tag
     */
    @Override
    public void onTagDiscovered(Tag tag) {
        Log.i(TAG, "New tag discovered");
        // Android's Host-based Card Emulation (HCE) feature implements the ISO-DEP (ISO 14443-4)
        // protocol.
        //
        // In order to communicate with a device using HCE, the discovered tag should be processed
        // using the IsoDep class.
        IsoDep isoDep = IsoDep.get(tag);
        if (isoDep != null) {
            try {
                // Connect to the remote NFC device
                isoDep.connect();
                // Build SELECT AID command for our loyalty card service.
                // This command tells the remote device which service we wish to communicate with.
                Log.i(TAG, "Requesting remote AID: " + SAMPLE_LOYALTY_CARD_AID);
                byte[] command = BuildSelectApdu(SAMPLE_LOYALTY_CARD_AID);
                // Send command to remote device
                Log.i(TAG, "Sending: " + ByteArrayToHexString(command));
                byte[] result = isoDep.transceive(command);
                // If AID is successfully selected, 0x9000 is returned as the status word (last 2
                // bytes of the result) by convention. Everything before the status word is
                // optional payload, which is used here to hold the account number.
                int resultLength = result.length;
                byte[] statusWord = {result[resultLength - 2], result[resultLength - 1]};
                byte[] payload = Arrays.copyOf(result, resultLength - 2);
                if (Arrays.equals(SELECT_OK_SW, statusWord)) {
                    // The remote NFC device will immediately respond with its stored account number
                    String accountNumber = new String(payload, "UTF-8");
                    Log.i(TAG, "Received: " + accountNumber);
                    // Inform CardReaderFragment of received account number
                    mAccountCallback.get().onAccountReceived(accountNumber);
                }
            } catch (IOException e) {
                Log.e(TAG, "Error communicating with card: " + e.toString());
            }
        } else {
            Ndef ndef = Ndef.get(tag);
            if (ndef == null) {
                // NDEF is not supported by this Tag.
                Log.d("NFCCardTagNDEF", "even this is null");
//                return;
            }

            NdefMessage ndefMessage = ndef.getCachedNdefMessage();

            if (ndefMessage == null) {
                Log.d("NFCCardTagNDEF", "ndef message is null");
//                return;
            }

            NdefRecord[] records = ndefMessage.getRecords();
            String text = ndefRecordToString(records[0]);
            Log.d("NFCCardTagNFC", "old" + text);
            mAccountCallback.get().onAccountReceived(text);
        }
    }


    public String ndefRecordToString(NdefRecord record) {
        byte[] payload = record.getPayload();
        return new String(payload);
    }

    /**
     * Build APDU for SELECT AID command. This command indicates which service a reader is
     * interested in communicating with. See ISO 7816-4.
     *
     * @param aid Application ID (AID) to select
     * @return APDU for SELECT AID command
     */
    public static byte[] BuildSelectApdu(String aid) {
        // Format: [CLASS | INSTRUCTION | PARAMETER 1 | PARAMETER 2 | LENGTH | DATA]
        return HexStringToByteArray(SELECT_APDU_HEADER + String.format("%02X", aid.length() / 2) + aid);
    }

    /**
     * Utility class to convert a byte array to a hexadecimal string.
     *
     * @param bytes Bytes to convert
     * @return String, containing hexadecimal representation.
     */
    public static String ByteArrayToHexString(byte[] bytes) {
        final char[] hexArray = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
        char[] hexChars = new char[bytes.length * 2];
        int v;
        for (int j = 0; j < bytes.length; j++) {
            v = bytes[j] & 0xFF;
            hexChars[j * 2] = hexArray[v >>> 4];
            hexChars[j * 2 + 1] = hexArray[v & 0x0F];
        }
        return new String(hexChars);
    }

    /**
     * Utility class to convert a hexadecimal string to a byte string.
     * <p>
     * <p>Behavior with input strings containing non-hexadecimal characters is undefined.
     *
     * @param s String containing hexadecimal characters to convert
     * @return Byte array generated from input
     */
    public static byte[] HexStringToByteArray(String s) {
        int len = s.length();
        byte[] data = new byte[len / 2];
        for (int i = 0; i < len; i += 2) {
            data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
                    + Character.digit(s.charAt(i + 1), 16));
        }
        return data;
    }

}

任何帮助将不胜感激

最佳答案

通常，对于此错误您无能为力。 IsoDep.connect() 上的 IOException(或更具体的 TagLostException)表示读取电话无法启动与 HCE 设备的通信。这通常是由于耦合不良(例如天线尺寸不匹配、天线设计不良、天线部分被设备电池覆盖而天线设计不当等)或加电时间长(通常仅使用无源卡和不适用于 HCE)。因此，通常此错误不是由通信协议(protocol)的逻辑问题(您可以通过软件修复)引起的，而是由设备的物理特性问题引起的(通常需要修改硬件)。

不幸的是，您对此无能为力。可能的解决方法是:

1. 尽量将两部手机更好地放在一起(以便阅读器设备天线和 HCE 设备天线)彼此对齐，并且设备外壳或设备电池的金属部分不会覆盖其他设备的天线.如果天线尺寸明显不同，请尝试将天线的其他边界彼此对齐，以便较小的位于较大的内部。

2. 在某些(!)设备上，它可能有助于在调用 connect() 之前增加收发超时:

   isoDep.setTimeout(10000);
   

   但是，在大多数设备上调用 connect 之前，此超时似乎没有任何影响。

3. 存在用于 NFC 的天线“助推器”，它可以使 HF 共振频率失谐以获得更好的匹配，减轻耦合问题以适应电池周围的天线形状，或者完全取代原始天线。我在这方面没有太多经验，无法引用此类助推器的任何来源。

编辑

重新阅读您的问题后，如果您在阅读器设备上设置标志 NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK，cr100 和 HCE 设备之间的通信似乎可以正常工作。如果是这种情况，IOException 可能确实是由逻辑错误引起的。在这种情况下，可能是 cr100 有一个损坏的 NFC 发现实现，如果 ISO-DEP 卡(例如 HCE 设备)没有实现 NDEF 标签规范，它就会中断。虽然我认为这不太可能，但您可以通过在 HCE 应用程序中实现 Type 4 标签应用程序来轻松测试它。参见 my answer here和 source code here有关如何执行此操作的示例。

关于android - 基于主机的卡仿真的 IOException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44967567/