CODEWITHSUNDEEP
androidandroid-intentnfc
ollie299792458
ollie299792458

Reputation: 256

Scan and recieve all nfc tags when open, but none when closed

I have an app that scans several things, when it gets round to nfc it launches an activity that prompts the user to scan nfc, how should I make it so that it only receives nfc when this activity is open? (Some form of active listener, like the difference between receiving a shared image from the gallery and launching a camera intent for result).

Or, if you could suggest an app that functions similarly to zxings barcode scanner (you can start it for result and it returns the data).

Upvotes: 0

Views: 219

Answers (1)

Stephan Branczyk
Stephan Branczyk

Reputation: 9375

To enable foreground NFC dispatching, just use a pending intent inside your Activity.

http://developer.android.com/guide/topics/connectivity/nfc/advanced-nfc.html#foreground-dispatch

Here is an actual working sample from API Demos: (which is also available here on Google Play)

package com.example.android.apis.nfc;
import com.example.android.apis.R;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.IntentFilter.MalformedMimeTypeException;
import android.nfc.NfcAdapter;
import android.nfc.tech.NfcF;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
/**
 * An example of how to use the NFC foreground dispatch APIs. This will intercept any MIME data
 * based NDEF dispatch as well as all dispatched for NfcF tags.
 */
public class ForegroundDispatch extends Activity {
    private NfcAdapter mAdapter;
    private PendingIntent mPendingIntent;
    private IntentFilter[] mFilters;
    private String[][] mTechLists;
    private TextView mText;
    private int mCount = 0;
    @Override
    public void onCreate(Bundle savedState) {
        super.onCreate(savedState);
        setContentView(R.layout.foreground_dispatch);
        mText = (TextView) findViewById(R.id.text);
        mText.setText("Scan a tag");
        mAdapter = NfcAdapter.getDefaultAdapter(this);
        // Create a generic PendingIntent that will be deliver to this activity. The NFC stack
        // will fill in the intent with the details of the discovered tag before delivering to
        // this activity.
        mPendingIntent = PendingIntent.getActivity(this, 0,
                new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
        // Setup an intent filter for all MIME based dispatches
        IntentFilter ndef = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
        try {
            ndef.addDataType("*/*");
        } catch (MalformedMimeTypeException e) {
            throw new RuntimeException("fail", e);
        }
        mFilters = new IntentFilter[] {
                ndef,
        };
        // Setup a tech list for all NfcF tags
        mTechLists = new String[][] { new String[] { NfcF.class.getName() } };
    }
    @Override
    public void onResume() {
        super.onResume();
        if (mAdapter != null) mAdapter.enableForegroundDispatch(this, mPendingIntent, mFilters,
                mTechLists);
    }
    @Override
    public void onNewIntent(Intent intent) {
        Log.i("Foreground dispatch", "Discovered tag with intent: " + intent);
        mText.setText("Discovered tag " + ++mCount + " with intent: " + intent);
    }
    @Override
    public void onPause() {
        super.onPause();
        if (mAdapter != null) mAdapter.disableForegroundDispatch(this);
    }
}

Upvotes: 1

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