Android -- 读取NFC卡号

Posted 2020-08-20 _iorilan

1. menifest文件中需要添加：

<uses-permission android:name="android.permission.NFC" />
<uses-feature
    android:name="android.hardware.nfc"
    android:required="true" />

在activity中添加：

<intent-filter>
    <action android:name="android.nfc.action.TAG_DISCOVERED" />
    <category android:name="android.intent.category.DEFAULT" />
</intent-filter>

2. 初始化时代码： 

Intent nfcIntent = new Intent(this, getClass());
nfcIntent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
mPendingIntent =
        PendingIntent.getActivity(this, 0,nfcIntent , 0);


mAdapter = NfcAdapter.getDefaultAdapter(this);
if (mAdapter == null) {
    Toast.makeText(getApplicationContext(), "NFC feature is supported on this device.", Toast.LENGTH_SHORT).show();
    return;
}

需要Override的函数：

 private NfcAdapter mAdapter;
    private PendingIntent mPendingIntent;
    @TargetApi(Build.VERSION_CODES.GINGERBREAD_MR1)
    protected void onResume() {
        super.onResume();
        mAdapter.enableForegroundDispatch(this, mPendingIntent, null, null);
    }


    @Override
    protected void onNewIntent(Intent intent){
        getTagInfo(intent);
    }
    @TargetApi(Build.VERSION_CODES.GINGERBREAD_MR1)
    private void getTagInfo(Intent intent) {
        Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
        byte[] tagId = tag.getId();
        String str = ByteArrayToHexString(tagId);
        str = flipHexStr(str);
        Long cardNo = Long.parseLong(str, 16);


        String ignoreOperationId = m_operationid;
        if(m_isOnline){
            // if select all , pass in the operation id encoded in ticket
            // there should NOT be many operations, take the only one

            new CardValidationAsyncTask().execute(cardNo.toString());
        }
    }




    @TargetApi(Build.VERSION_CODES.GINGERBREAD_MR1)
    @Override
    protected void onPause() {
        super.onPause();
        if (mAdapter != null) {
            mAdapter.disableForegroundDispatch(this);
        }
    }

以下为helper函数：
   

 private String flipHexStr(String s){
        StringBuilder  result = new StringBuilder();
        for (int i = 0; i <=s.length()-2; i=i+2) {
            result.append(new StringBuilder(s.substring(i,i+2)).reverse());
        }
        return result.reverse().toString();
    }


    private String ByteArrayToHexString(byte[] inarray) {
        int i, j, in;
        String[] hex = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A",
                "B", "C", "D", "E", "F" };
        String out = "";


        for (j = 0; j < inarray.length; ++j) {
            in = (int) inarray[j] & 0xff;
            i = (in >> 4) & 0x0f;
            out += hex[i];
            i = in & 0x0f;
            out += hex[i];
        }
        return out;
    }