方法 onNewIntent(intent) 不在 NFC 中执行

Question

I am implementing the NFC in android project. I have written the entries which are required in the AndroidManifest.xml and Java code.

When any tag come near by device then my app detect the tag then it open the activity but here I am getting NFC Tag Info but onNewIntent is not executing.

Please guys share your views.

public class NFCActivity extends Activity {

    private NfcAdapter mNFCAdapter;
    private PendingIntent mNfcPendingIntent;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_nfc);

        // Create the OpenSqliteHelper object. It always best to create only
        // once instance of this OpenSqliteHelper
        DatabaseManager.init(this);

        mNFCAdapter = NfcAdapter.getDefaultAdapter(this);

        if (mNFCAdapter == null) {
            // Device does not support NFC
            Toast.makeText(this,
                    getString(R.string.device_does_not_support_nfc),
                    Toast.LENGTH_LONG).show();
        } else {
            if (!mNFCAdapter.isEnabled()) {
                // NFC is disabled
                Toast.makeText(this, getString(R.string.enable_nfc),
                        Toast.LENGTH_LONG).show();
            } else {
                mNfcPendingIntent = PendingIntent.getActivity(NFCActivity.this,
                        0, new Intent(NFCActivity.this, NFCActivity.class)
                                .addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
            }
        }
        finish();
    }

    @Override
    protected void onNewIntent(Intent intent) {
        Tag mTag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
    }

    @Override
    protected void onPause() {
        super.onPause();
        mNFCAdapter.disableForegroundDispatch(this);
    }

    @Override
    public void onResume() {
        super.onResume();
        mNFCAdapter.enableForegroundDispatch(this, mNfcPendingIntent, null,
                null);
    }
}

AndroidManifest.xml

<activity
    android:name="net.livepatrols.thepartnerSA.NFCActivity"
    android:theme="@android:style/Theme.NoDisplay" >
    <intent-filter>
        <action android:name="android.nfc.action.TECH_DISCOVERED" />
    </intent-filter>

    <meta-data
        android:name="android.nfc.action.TECH_DISCOVERED"
        android:resource="@xml/nfc_tech_filter" />

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

        <category android:name="android.intent.category.DEFAULT" />
    </intent-filter>
</activity>

Answer 1

Your code works fine when your activity is on foreground, but it won't work when the Activity is started by an Intent with android.nfc.action.XXX_DISCOVERED action. As it is the first intent, onNewIntent() won't be called, but you can use the intent in your onCreate() method. You should call your NFC logic from onCreate() and from onNewIntent() , validating the action before accessing the tag.

public class NFCActivity extends Activity {

    private NfcAdapter mNFCAdapter;
    private PendingIntent mNfcPendingIntent;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ...
        performTagOperations(getIntent());
    }

    @Override
    protected void onNewIntent(Intent intent) {
        performTagOperations(intent);
    }

    private void performTagOperations(Intent intent){
        String action = intent.getAction();
        if(action.equals(NfcAdapter.ACTION_TAG_DISCOVERED) ||
        action.equals(NfcAdapter.ACTION_TECH_DISCOVERED) ){
            //PERFORM TAG OPERATIONS
        }
    }
    ...
}

Answer 2

In my case the problem was, that I followed the documentation for nfcAdapter.enableForegroundDispatch(...) blindly and I pasted this code into fragment :

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

Since it actually expects activity, just change all to this to getContext() and especially getClass() .

pendingIntent = PendingIntent.getActivity(
            getContext(),
            0,
            new Intent(getContext(), getContext().getClass())
                .addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);