Nfc标签上的ID是否不唯一? [英] Id on Nfc tag not unique?

问题描述

我正在读取android手机上的nfc标签，我写给标签的值是这样写的:

I am reading nfc tags on android phone, there is value which I written to the tag which I read like this:

@Override
protected String doInBackground(Tag... params) {
    Tag tag = params[0];

    Ndef ndef = Ndef.get(tag);
    if (ndef == null) {
        // NDEF is not supported by this Tag.
        return null;
    }

    NdefMessage ndefMessage = ndef.getCachedNdefMessage();

    NdefRecord[] records = ndefMessage.getRecords();
    for (NdefRecord ndefRecord : records) {
        if (ndefRecord.getTnf() == NdefRecord.TNF_WELL_KNOWN && Arrays.equals(ndefRecord.getType(), NdefRecord.RTD_TEXT)) {
            try {
                return readText(ndefRecord);
            } catch (UnsupportedEncodingException e) {
                Log.e(TAG, "Unsupported Encoding", e);
            }
        }
    }
    return null;
}

private String readText(NdefRecord record) throws UnsupportedEncodingException {
    byte[] payload = record.getPayload();
    String textEncoding = ((payload[0] & 128) == 0) ? "UTF-8" : "UTF-16";                                               // Get the Text Encoding
    int languageCodeLength = payload[0] & 0063;                                                                         // Get the Language Code
    return new String(payload, languageCodeLength + 1, payload.length - languageCodeLength - 1, textEncoding);          // Get the Text
}

我尝试过，并且应该有一个只读的NfcTag唯一ID:

And there should be a unique Id of the NfcTag which is read only, I tried:

     Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
     mNfcId = tag.getId().toString();

但这在下次阅读时给出了不同的结果！！！ 如何从nfc标签读取唯一的只读标签?

But this is giving different results on next read !!! How can I read the unique read only tag from nfc Tag ?

推荐答案

出于隐私原因，有些标签没有唯一的ID.大多数包含NFC芯片的旅行证件和信用卡都在其中.

There are tags that don't have a unique ID for privacy reasons. Most travel documents and credit cards that contain an NFC chip are among them.

也:不要指望您可以读取的ID的唯一性.这些很容易被伪造.同样，许多NFC标签制造商也不保证ID的全球唯一性.

Also: Don't count on the uniqueness of the IDs you can read. These can easily be faked. Also many manufacturers of NFC tags don't guarantee the worldwide uniqueness of the ID.

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