android/beam/Beam.java

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.beam;

import android.app.Activity;
import android.content.Intent;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.NfcAdapter.CreateNdefMessageCallback;
import android.nfc.NfcAdapter.OnNdefPushCompleteCallback;
import android.nfc.NfcEvent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.Parcelable;
import android.provider.Settings;
import android.text.format.Time;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;

import java.nio.charset.Charset;


public class Beam extends Activity implements CreateNdefMessageCallback,
        OnNdefPushCompleteCallback {
    NfcAdapter mNfcAdapter;
    TextView mInfoText;
    private static final int MESSAGE_SENT = 1;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mInfoText = (TextView) findViewById(R.id.textView);
        // Check for available NFC Adapter
        mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
        if (mNfcAdapter == null) {
            mInfoText = (TextView) findViewById(R.id.textView);
            mInfoText.setText("NFC is not available on this device.");
        }
        // Register callback to set NDEF message
        mNfcAdapter.setNdefPushMessageCallback(this, this);
        // Register callback to listen for message-sent success
        mNfcAdapter.setOnNdefPushCompleteCallback(this, this);
    }


    /**
     * Implementation for the CreateNdefMessageCallback interface
     */
    @Override
    public NdefMessage createNdefMessage(NfcEvent event) {
        Time time = new Time();
        time.setToNow();
        String text = ("Beam me up!\n\n" +
                "Beam Time: " + time.format("%H:%M:%S"));
        NdefMessage msg = new NdefMessage(
                new NdefRecord[] { createMimeRecord(
                        "application/com.example.android.beam", text.getBytes())
         /**
          * The Android Application Record (AAR) is commented out. When a device
          * receives a push with an AAR in it, the application specified in the AAR
          * is guaranteed to run. The AAR overrides the tag dispatch system.
          * You can add it back in to guarantee that this
          * activity starts when receiving a beamed message. For now, this code
          * uses the tag dispatch system.
          */
          //,NdefRecord.createApplicationRecord("com.example.android.beam")
        });
        return msg;
    }

    /**
     * Implementation for the OnNdefPushCompleteCallback interface
     */
    @Override
    public void onNdefPushComplete(NfcEvent arg0) {
        // A handler is needed to send messages to the activity when this
        // callback occurs, because it happens from a binder thread
        mHandler.obtainMessage(MESSAGE_SENT).sendToTarget();
    }

    /** This handler receives a message from onNdefPushComplete */
    private final Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case MESSAGE_SENT:
                Toast.makeText(getApplicationContext(), "Message sent!", Toast.LENGTH_LONG).show();
                break;
            }
        }
    };

    @Override
    public void onResume() {
        super.onResume();
        // Check to see that the Activity started due to an Android Beam
        if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {
            processIntent(getIntent());
        }
    }

    @Override
    public void onNewIntent(Intent intent) {
        // onResume gets called after this to handle the intent
        setIntent(intent);
    }

    /**
     * Parses the NDEF Message from the intent and prints to the TextView
     */
    void processIntent(Intent intent) {
        Parcelable[] rawMsgs = intent.getParcelableArrayExtra(
                NfcAdapter.EXTRA_NDEF_MESSAGES);
        // only one message sent during the beam
        NdefMessage msg = (NdefMessage) rawMsgs[0];
        // record 0 contains the MIME type, record 1 is the AAR, if present
        mInfoText.setText(new String(msg.getRecords()[0].getPayload()));
    }

    /**
     * Creates a custom MIME type encapsulated in an NDEF record
     *
     * @param mimeType
     */
    public NdefRecord createMimeRecord(String mimeType, byte[] payload) {
        byte[] mimeBytes = mimeType.getBytes(Charset.forName("US-ASCII"));
        NdefRecord mimeRecord = new NdefRecord(
                NdefRecord.TNF_MIME_MEDIA, mimeBytes, new byte[0], payload);
        return mimeRecord;
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // If NFC is not available, we won't be needing this menu
        if (mNfcAdapter == null) {
            return super.onCreateOptionsMenu(menu);
        }
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.options, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.menu_settings:
                Intent intent = new Intent(Settings.ACTION_NFCSHARING_SETTINGS);
                startActivity(intent);
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }
}