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| 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 package org.chromium.device.nfc; |
| 6 |
| 7 import android.nfc.FormatException; |
| 8 import android.nfc.NdefMessage; |
| 9 import android.nfc.Tag; |
| 10 import android.nfc.TagLostException; |
| 11 import android.nfc.tech.Ndef; |
| 12 import android.nfc.tech.NdefFormatable; |
| 13 import android.nfc.tech.TagTechnology; |
| 14 |
| 15 import java.io.IOException; |
| 16 |
| 17 /** |
| 18 * Utility class that provides I/O operations for NFC tags. |
| 19 */ |
| 20 public final class NfcTagHandler { |
| 21 private final TagTechnology mTech; |
| 22 private final TagTechnologyHandler mTechHandler; |
| 23 private boolean mWasConnected; |
| 24 |
| 25 /** |
| 26 * Factory method that creates NfcTagHandler for a given NFC Tag. |
| 27 * |
| 28 * @param tag @see android.nfc.Tag |
| 29 * @return NfcTagHandler or null when unsupported Tag is provided. |
| 30 */ |
| 31 public static NfcTagHandler create(Tag tag) { |
| 32 if (tag == null) return null; |
| 33 |
| 34 Ndef ndef = Ndef.get(tag); |
| 35 if (ndef != null) return new NfcTagHandler(ndef, new NdefHandler(ndef)); |
| 36 |
| 37 NdefFormatable formattable = NdefFormatable.get(tag); |
| 38 if (formattable != null) { |
| 39 return new NfcTagHandler(formattable, new NdefFormattableHandler(for
mattable)); |
| 40 } |
| 41 |
| 42 return null; |
| 43 } |
| 44 |
| 45 /** |
| 46 * NdefFormatable and Ndef interfaces have different signatures for operatin
g with NFC tags. |
| 47 * This interface provides generic methods. |
| 48 */ |
| 49 private interface TagTechnologyHandler { |
| 50 public void write(NdefMessage message) |
| 51 throws IOException, TagLostException, FormatException; |
| 52 // TODO(crbug.com/625589): add read method for nfc.watch. |
| 53 } |
| 54 |
| 55 /** |
| 56 * Implementation of TagTechnologyHandler that uses Ndef tag technology. |
| 57 * @see android.nfc.tech.Ndef |
| 58 */ |
| 59 private static class NdefHandler implements TagTechnologyHandler { |
| 60 private final Ndef mNdef; |
| 61 |
| 62 NdefHandler(Ndef ndef) { |
| 63 mNdef = ndef; |
| 64 } |
| 65 |
| 66 public void write(NdefMessage message) |
| 67 throws IOException, TagLostException, FormatException { |
| 68 mNdef.writeNdefMessage(message); |
| 69 } |
| 70 } |
| 71 |
| 72 /** |
| 73 * Implementation of TagTechnologyHandler that uses NdefFormatable tag techn
ology. |
| 74 * @see android.nfc.tech.NdefFormatable |
| 75 */ |
| 76 private static class NdefFormattableHandler implements TagTechnologyHandler
{ |
| 77 private final NdefFormatable mNdefFormattable; |
| 78 |
| 79 NdefFormattableHandler(NdefFormatable ndefFormattable) { |
| 80 mNdefFormattable = ndefFormattable; |
| 81 } |
| 82 |
| 83 public void write(NdefMessage message) |
| 84 throws IOException, TagLostException, FormatException { |
| 85 mNdefFormattable.format(message); |
| 86 } |
| 87 } |
| 88 |
| 89 private NfcTagHandler(TagTechnology tech, TagTechnologyHandler handler) { |
| 90 mTech = tech; |
| 91 mTechHandler = handler; |
| 92 } |
| 93 |
| 94 /** |
| 95 * Connects to NFC tag. |
| 96 */ |
| 97 public void connect() throws IOException, TagLostException { |
| 98 if (!mTech.isConnected()) { |
| 99 mTech.connect(); |
| 100 mWasConnected = true; |
| 101 } |
| 102 } |
| 103 |
| 104 /** |
| 105 * Closes connection. |
| 106 */ |
| 107 public void close() throws IOException { |
| 108 mTech.close(); |
| 109 } |
| 110 |
| 111 /** |
| 112 * Writes NdefMessage to NFC tag. |
| 113 */ |
| 114 public void write(NdefMessage message) throws IOException, TagLostException,
FormatException { |
| 115 mTechHandler.write(message); |
| 116 } |
| 117 |
| 118 /** |
| 119 * If tag was previously connected and subsequent connection to the same tag
fails, consider |
| 120 * tag to be out of range. |
| 121 */ |
| 122 public boolean isTagOutOfRange() { |
| 123 try { |
| 124 connect(); |
| 125 } catch (IOException e) { |
| 126 return mWasConnected; |
| 127 } |
| 128 return false; |
| 129 } |
| 130 } |
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