当用户扫描 nfc 时从标记读取 nfc 消息

Question

我需要在用户扫描 nfc 标签的同时打开我的应用程序并读取 nfc 消息。

目前，当用户点击或扫描 nfc 时，我可以打开我的，但我无法同时读取 nfc 中的数据。

@TargetApi(Build.VERSION_CODES.GINGERBREAD)

@SuppressLint（"NewApi"）公共类 主活动扩展活动 {

public static final String TAG = "NfcDemo";
private TextView mTextView;
// private NfcAdapter mNfcAdapter;
protected PendingIntent nfcPendingIntent;
NfcAdapter nfcAdapter;
IntentFilter[] readTagFilters;
PendingIntent pendingIntent;
Tag detectedTag;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mTextView = (TextView) findViewById(R.id.textView1);
    nfcAdapter = NfcAdapter.getDefaultAdapter(this);
    detectedTag = getIntent().getParcelableExtra(NfcAdapter.EXTRA_TAG);
    pendingIntent = PendingIntent.getActivity(this, 0, new Intent(this,this.getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
    IntentFilter tagDetected = new IntentFilter(
            NfcAdapter.ACTION_TAG_DISCOVERED);
    IntentFilter filter2 = new IntentFilter(
            NfcAdapter.ACTION_NDEF_DISCOVERED);
    readTagFilters = new IntentFilter[] { tagDetected, filter2 };
    Log.d(TAG, "ok" + getIntent().getAction());

}
public void enableForegroundMode() {
    Log.d(TAG, "enableForegroundMode");
    IntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED); 
    Log.d("done ", "in " + tagDetected.getAction(0));
    IntentFilter[] writeTagFilters = new IntentFilter[] { tagDetected };
}
@Override
protected void onResume() {
    Log.d(TAG, "onResume");
    super.onResume();
    nfcAdapter.enableForegroundDispatch(this, pendingIntent,readTagFilters, null);
    Intent ndefDetected = new Intent(NfcAdapter.ACTION_TAG_DISCOVERED);
    Tag tag = ndefDetected.getParcelableExtra(NfcAdapter.EXTRA_TAG);
    Parcelable[] rawMsgs = ndefDetected .getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
    if (rawMsgs != null) {
        Log.d(TAG, "onResume1");
    } else {
        Log.d(TAG, "onResume2");
    }
}
@Override
protected void onPause() {
    Log.d(TAG, "onPause");
    super.onPause();
    if (NfcAdapter.getDefaultAdapter(this) != null)
        NfcAdapter.getDefaultAdapter(this).disableForegroundDispatch(this);
}
@Override
protected void onNewIntent(Intent intent) {
    // TODO Auto-generated method stub
    setIntent(intent);
    Log.d(TAG, "NewIntent is ...." + intent.getAction() + "....."
            + NfcAdapter.ACTION_NDEF_DISCOVERED);
    getTagMsg(intent);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}
public void getTagMsg(Intent intent) {
    Log.d(TAG, "getTagContent" + intent.getAction() + "....."
            + NfcAdapter.ACTION_NDEF_DISCOVERED);
    if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(intent.getAction())) {
        Log.d(TAG, "New Intent/1");
        NdefMessage[] messages = null;
        Parcelable[] rawMsgs = intent
                .getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
        if (rawMsgs != null) {
            messages = new NdefMessage[rawMsgs.length];
            Log.d(TAG, "New Intent/2:" + messages);
            for (int i = 0; i < rawMsgs.length; i++) {
                messages[i] = (NdefMessage) rawMsgs[i];
            }
        }
        if (messages[0] != null) {
            String result = "";
            byte[] payload = messages[0].getRecords()[0].getPayload();
            // this assumes that we get back am SOH followed by host/code
            for (int b = 0; b < payload.length; b++) { // skip SOH
                result += (char) payload[b];
            }
            Log.d(TAG, "New Intent/3:" + result);
            Toast.makeText(getApplicationContext(),
                    "Tag Contains " + result, Toast.LENGTH_SHORT).show();
        }
    }
}

}

Answer 1

当你的活动开始时，你并没有真正做任何事情。您应该在活动onCreate中从Intent中抓取的标签上调用getTagMsg。在方法的末尾，只需调用 getTagMsg(detectedTag) 即可。

您可能应该有一个从Intent开始的帮助程序方法，获取可解析的额外内容，并从中读取标记的内容。然后，您可以在onCreate和onNewIntent中使用此方法。