我正在做一个应用程序，可以读取nfc，然后处理的内容消息，但我只希望某些人能够阅读标签。因此，在某种程度上，我希望用户扫描标签并在能够读取标签之前提示输入密码。这可能吗？愿意接受任何想法。也可以只保留读取模式，并将写入模式更改为在标签上写入密码的类型，以确保其安全。

btnWrite.setOnClickListener(new View.OnClickListener()
            {
                @Override
                public void onClick(View v) {
                    try {
                        if(myTag ==null) {
                            Toast.makeText(context, ERROR_DETECTED, Toast.LENGTH_LONG).show();
                        } else {
                            write(message.getText().toString(), myTag);
                            Toast.makeText(context, WRITE_SUCCESS, Toast.LENGTH_LONG ).show();
                        }
                    } catch (IOException e) {
                        Toast.makeText(context, WRITE_ERROR, Toast.LENGTH_LONG ).show();
                        e.printStackTrace();
                    } catch (FormatException e) {
                        Toast.makeText(context, WRITE_ERROR, Toast.LENGTH_LONG ).show();
                        e.printStackTrace();
                    }
                }
            });

            nfcAdapter = NfcAdapter.getDefaultAdapter(this);
            if (nfcAdapter == null) {
                // Stop here, we definitely need NFC
                Toast.makeText(this, "This device doesn't support NFC.", Toast.LENGTH_LONG).show();
                finish();
            }
            readFromIntent(getIntent());

            pendingIntent = PendingIntent.getActivity(this, 0, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
            IntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);
            tagDetected.addCategory(Intent.CATEGORY_DEFAULT);
            writeTagFilters = new IntentFilter[] { tagDetected };
        }

        private void readFromIntent(Intent intent) {
            String action = intent.getAction();
            if (NfcAdapter.ACTION_TAG_DISCOVERED.equals(action)
                    || NfcAdapter.ACTION_TECH_DISCOVERED.equals(action)
                    || NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)) {
                Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
                NdefMessage[] msgs = null;
                if (rawMsgs != null) {
                    msgs = new NdefMessage[rawMsgs.length];
                    for (int i = 0; i < rawMsgs.length; i++) {
                        msgs[i] = (NdefMessage) rawMsgs[i];
                    }
                }
                buildTagViews(msgs);
            }
        }
        private void buildTagViews(NdefMessage[] msgs) {
            if (msgs == null || msgs.length == 0) return;

            String text = "";
//        String tagId = new String(msgs[0].getRecords()[0].getType());
            byte[] payload = msgs[0].getRecords()[0].getPayload();
            String textEncoding = ((payload[0] & 128) == 0) ? "UTF-8" : "UTF-16"; // Get the Text Encoding
            int languageCodeLength = payload[0] & 0063; // Get the Language Code, e.g. "en"
            // String languageCode = new String(payload, 1, languageCodeLength, "US-ASCII");

            try {
                // Get the Text
                text = new String(payload, languageCodeLength + 1, payload.length - languageCodeLength - 1, textEncoding);
            } catch (UnsupportedEncodingException e) {
                Log.e("UnsupportedEncoding", e.toString());
            }
            tvNFCContent.setText(text+"\n( taille de la trame: " + text.length () +")");
        }
        private void write(String text, Tag tag) throws IOException, FormatException {
            NdefRecord[] records = { createRecord(text) };
            NdefMessage message = new NdefMessage(records);
            // Get an instance of Ndef for the tag.
            Ndef ndef = Ndef.get(tag);
            // Enable I/O
            ndef.connect();
            // Write the message
            ndef.writeNdefMessage(message);
            // Close the connection
            ndef.close();
        }
        private NdefRecord createRecord(String text) throws UnsupportedEncodingException {
            String lang       = "en";
            byte[] textBytes  = text.getBytes();
            byte[] langBytes  = lang.getBytes("US-ASCII");
            int    langLength = langBytes.length;
            int    textLength = textBytes.length;
            byte[] payload    = new byte[1 + langLength + textLength];

            // set status byte (see NDEF spec for actual bits)
            payload[0] = (byte) langLength;

            // copy langbytes and textbytes into payload
            System.arraycopy(langBytes, 0, payload, 1,              langLength);
            System.arraycopy(textBytes, 0, payload, 1 + langLength, textLength);

            NdefRecord recordNFC = new NdefRecord(NdefRecord.TNF_WELL_KNOWN,  NdefRecord.RTD_TEXT,  new byte[0], payload);

            return recordNFC;
        }

        @Override
        protected void onNewIntent(Intent intent) {
            setIntent(intent);
            readFromIntent(intent);
            if(NfcAdapter.ACTION_TAG_DISCOVERED.equals(intent.getAction())){
                myTag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
            }
        }

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

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

        private void WriteModeOn(){
            writeMode = true;
            nfcAdapter.enableForegroundDispatch(this, pendingIntent, writeTagFilters, null);
        }
        private void WriteModeOff(){
            writeMode = false;
            nfcAdapter.disableForegroundDispatch(this);
        }
    }