Question

我试图检测是否有手机已经扫描过的标签，而不是从历史记录发出的意图。

问题在于，当我扫描标签时，会抛出异常，就像connect（）失败一样。

我将手机放在标签上，以便有足够的时间阅读标签。

为什么连接失败的任何想法？

提前致谢。

Log.e(TAG, "just scanned an nfc tag and DB must be empty");
                Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);

                tagId = bytesToHexString(tag.getId());
                Log.e(TAG, "tagId immediately after scanning nfc tag = " + tagId);

                if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {






                    Ndef ndefTag = Ndef.get(tag);

                    try {
                        ndefTag.connect();  // this should already perform an IO operation and should therefore fail if there is no tag
                       // NdefMessage ndefMsg = ndefTag.getNdefMessage();  // this reads the current NDEF message from the tag and consequently causes an IO operation
                    } catch (Exception e) {
                        // there is no tag or communication with tag dropped
                        Log.e(TAG, "There a problem with connecting to the tag using Ndef.connect(");
                    } finally {
                        try {
                            ndefTag.close();
                        } catch (Exception e) {
                        }
                    }








                    Log.e(TAG, "A formatted NFC Tag just scanned");

   06-02 13:32:30.226: E/NfcscannerActivity(24683): formatted three days ago time = 30/May/14 13:32pm
    06-02 13:32:30.226: E/LoginValidate(24683): scantime from db = 2014-06-02 11:40:20.187 specific time = 2014-05-30 13:32:30.237
    06-02 13:32:30.236: E/NfcscannerActivity(24683): action of intent = android.nfc.action.NDEF_DISCOVERED
    06-02 13:32:30.236: E/LoginValidate(24683): getting last tag touched
    06-02 13:32:30.236: E/NfcscannerActivity(24683): just scanned an nfc tag and DB must be empty
    06-02 13:32:30.246: I/System.out(24683): 04
    06-02 13:32:30.246: I/System.out(24683): 4e
    06-02 13:32:30.246: I/System.out(24683): 0e
    06-02 13:32:30.246: I/System.out(24683): 22
    06-02 13:32:30.246: I/System.out(24683): c2
    06-02 13:32:30.246: I/System.out(24683): 23
    06-02 13:32:30.246: I/System.out(24683): 84
    06-02 13:32:30.246: E/NfcscannerActivity(24683): tagId immediately after scanning nfc tag = 0x044e0e22c22384
    06-02 13:32:30.256: E/NfcscannerActivity(24683): There a problem with connecting to the tag using Ndef.connect(
    06-02 13:32:30.256: E/NfcscannerActivity(24683): A formatted NFC Tag just scanned
    06-02 13:32:30.256: E/NfcscannerActivity(24683): ndefrecord has a length of 1
    06-02 13:32:30.256: E/NfcscannerActivity(24683): TextRecord.text = 1,10,5,Alice riswell
    06-02 13:32:30.256: E/NfcscannerActivity(24683): payload has a length of 20

[EDIT1]

if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {


                    new Thread(new Runnable() {

                        @Override
                        public void run() {


                            Ndef ndefTag = Ndef.get(tag);

                            try {
                                Log.e(TAG, "about to test connect()********************************************");
                                ndefTag.connect();  // this should already perform an IO operation and should therefore fail if there is no tag
                                Log.e(TAG, "Ndef.connect() connected!********************************************");
                                NdefMessage ndefMsg = ndefTag.getNdefMessage();  // this reads the current NDEF message from the tag and consequently causes an IO operation

                            } catch (Exception e) {
                                // there is no tag or communication with tag dropped
                                Log.e(TAG, "There a problem with connecting to the tag using Ndef.connect(");
                            } finally {
                                try {
                                    ndefTag.close();
                                } catch (Exception e) {
                                }
                            }

                        }
                    }).start();

。

06-02 14:03:19.396: E/NfcscannerActivity(15153): we need to insert record as db empty
06-02 14:03:19.396: E/NfcscannerActivity(15153): about to test connect()********************************************
06-02 14:03:19.396: E/NfcscannerActivity(15153): formattedNowTime = 2014-06-02 14:03:19.405
06-02 14:03:19.396: E/NfcscannerActivity(15153): There a problem with connecting to the tag using Ndef.connect(

Answer 1

connect（）代码需要在一个单独的线程中运行，我需要权限

<uses-permission android:name="android.permission.NFC" />

ndefTag.connect（）没有连接到标签

1 个答案: