NFCManager.java

package com.survivingwithandroid.nfcwriter;
/*
 * Copyright (C) 2016, francesco Azzola 
 *
 *(http://www.survivingwithandroid.com)
 *
 * 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.
 *
 * 03/01/16
 */

import android.app.Activity;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.nfc.tech.NdefFormatable;
import android.support.design.widget.Snackbar;

import java.io.ByteArrayOutputStream;
import java.util.Locale;

public class NFCManager {

    private Activity activity;
    private NfcAdapter nfcAdpt;

    public NFCManager(Activity activity) {
        this.activity = activity;
    }

    public void verifyNFC() throws NFCNotSupported, NFCNotEnabled {

        nfcAdpt = NfcAdapter.getDefaultAdapter(activity);

        if (nfcAdpt == null)
            throw new NFCNotSupported();

        if (!nfcAdpt.isEnabled())
            throw new NFCNotEnabled();

    }

    public void enableDispatch() {
        Intent nfcIntent = new Intent(activity, getClass());
        nfcIntent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(activity, 0, nfcIntent, 0);
        IntentFilter[] intentFiltersArray = new IntentFilter[] {};
        String[][] techList = new String[][] { { android.nfc.tech.Ndef.class.getName() }, { android.nfc.tech.NdefFormatable.class.getName() } };


        nfcAdpt.enableForegroundDispatch(activity, pendingIntent, intentFiltersArray, techList);
    }

    public void disableDispatch() {
        nfcAdpt.disableForegroundDispatch(activity);
    }

    public static class NFCNotSupported extends Exception {

        public NFCNotSupported() {
            super();
        }
    }

    public static class NFCNotEnabled extends Exception {

        public NFCNotEnabled() {
            super();
        }
    }


    public void writeTag(Tag tag, NdefMessage message)  {
        if (tag != null) {
            try {
                Ndef ndefTag = Ndef.get(tag);

                if (ndefTag == null) {
                    // Let's try to format the Tag in NDEF
                    NdefFormatable nForm = NdefFormatable.get(tag);
                    if (nForm != null) {
                        nForm.connect();
                        nForm.format(message);
                        nForm.close();
                    }
                }
                else {
                    ndefTag.connect();
                    ndefTag.writeNdefMessage(message);
                    ndefTag.close();
                }
            }
            catch(Exception e) {
                e.printStackTrace();
            }
        }
    }

    public NdefMessage createUriMessage(String content, String type) {
        NdefRecord record = NdefRecord.createUri(type + content);
        NdefMessage msg = new NdefMessage(new NdefRecord[]{record});
        return msg;

    }

    public NdefMessage createTextMessage(String content) {
        try {
            // Get UTF-8 byte
            byte[] lang = Locale.getDefault().getLanguage().getBytes("UTF-8");
            byte[] text = content.getBytes("UTF-8"); // Content in UTF-8

            int langSize = lang.length;
            int textLength = text.length;

            ByteArrayOutputStream payload = new ByteArrayOutputStream(1 + langSize + textLength);
            payload.write((byte) (langSize & 0x1F));
            payload.write(lang, 0, langSize);
            payload.write(text, 0, textLength);
            NdefRecord record = new NdefRecord(NdefRecord.TNF_WELL_KNOWN, NdefRecord.RTD_TEXT, new byte[0], payload.toByteArray());
            return new NdefMessage(new NdefRecord[]{record});
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    public NdefMessage createExternalMessage(String content) {
        NdefRecord externalRecord = NdefRecord.createExternal("com.survivingwithandroid", "data", content.getBytes());

        NdefMessage ndefMessage = new NdefMessage(new NdefRecord[] { externalRecord });

        return ndefMessage;
    }
}