1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.apps.tag.record; 18 19 import com.android.apps.tag.R; 20 import com.google.common.annotations.VisibleForTesting; 21 import com.google.common.base.Preconditions; 22 import com.google.common.primitives.Bytes; 23 24 import android.app.Activity; 25 import android.content.Context; 26 import android.nfc.NdefRecord; 27 import android.view.LayoutInflater; 28 import android.view.View; 29 import android.view.ViewGroup; 30 import android.widget.TextView; 31 32 import java.io.UnsupportedEncodingException; 33 import java.nio.charset.Charset; 34 import java.util.Arrays; 35 import java.util.Locale; 36 37 /** 38 * An NFC Text Record 39 */ 40 public class TextRecord extends ParsedNdefRecord { 41 42 public static final String RECORD_TYPE = "TextRecord"; 43 44 /** ISO/IANA language code */ 45 private final String mLanguageCode; 46 private final String mText; 47 TextRecord(String languageCode, String text)48 private TextRecord(String languageCode, String text) { 49 mLanguageCode = Preconditions.checkNotNull(languageCode); 50 mText = Preconditions.checkNotNull(text); 51 } 52 53 @Override getView(Activity activity, LayoutInflater inflater, ViewGroup parent, int offset)54 public View getView(Activity activity, LayoutInflater inflater, ViewGroup parent, int offset) { 55 TextView text = (TextView) inflater.inflate(R.layout.tag_text, parent, false); 56 text.setText(mText); 57 return text; 58 } 59 60 @Override getSnippet(Context context, Locale locale)61 public String getSnippet(Context context, Locale locale) { 62 return mText; 63 } 64 getText()65 public String getText() { 66 return mText; 67 } 68 69 /** 70 * Returns the ISO/IANA language code associated with this text element. 71 * 72 * TODO: this should return a {@link java.util.Locale} 73 */ 74 @VisibleForTesting getLanguageCode()75 public String getLanguageCode() { 76 return mLanguageCode; 77 } 78 79 // TODO: deal with text fields which span multiple NdefRecords parse(NdefRecord record)80 public static TextRecord parse(NdefRecord record) { 81 Preconditions.checkArgument(record.getTnf() == NdefRecord.TNF_WELL_KNOWN); 82 Preconditions.checkArgument(Arrays.equals(record.getType(), NdefRecord.RTD_TEXT)); 83 try { 84 85 byte[] payload = record.getPayload(); 86 Preconditions.checkArgument(payload.length > 0); 87 88 /* 89 * payload[0] contains the "Status Byte Encodings" field, per 90 * the NFC Forum "Text Record Type Definition" section 3.2.1. 91 * 92 * bit7 is the Text Encoding Field. 93 * 94 * if (Bit_7 == 0): The text is encoded in UTF-8 95 * if (Bit_7 == 1): The text is encoded in UTF16 96 * 97 * Bit_6 is reserved for future use and must be set to zero. 98 * 99 * Bits 5 to 0 are the length of the IANA language code. 100 */ 101 102 String textEncoding = ((payload[0] & 0200) == 0) ? "UTF-8" : "UTF-16"; 103 int languageCodeLength = payload[0] & 0077; 104 Preconditions.checkArgument(payload.length - languageCodeLength - 1 >= 0); 105 106 String languageCode = new String(payload, 1, languageCodeLength, "US-ASCII"); 107 String text = new String(payload, 108 languageCodeLength + 1, 109 payload.length - languageCodeLength - 1, 110 textEncoding); 111 return new TextRecord(languageCode, text); 112 113 } catch (UnsupportedEncodingException e) { 114 // should never happen unless we get a malformed tag. 115 throw new IllegalArgumentException(e); 116 } 117 } 118 isText(NdefRecord record)119 public static boolean isText(NdefRecord record) { 120 try { 121 parse(record); 122 return true; 123 } catch (IllegalArgumentException e) { 124 return false; 125 } 126 } 127 128 @VisibleForTesting newTextRecord(String text, Locale locale)129 public static NdefRecord newTextRecord(String text, Locale locale) { 130 return newTextRecord(text, locale, true); 131 } 132 newTextRecord(String text, Locale locale, boolean encodeInUtf8)133 public static NdefRecord newTextRecord(String text, Locale locale, boolean encodeInUtf8) { 134 Preconditions.checkNotNull(text); 135 Preconditions.checkNotNull(locale); 136 137 byte[] langBytes = locale.getLanguage().getBytes(Charset.forName("US-ASCII")); 138 139 Charset utfEncoding = encodeInUtf8 ? Charset.forName("UTF-8") : Charset.forName("UTF-16"); 140 byte[] textBytes = text.getBytes(utfEncoding); 141 142 int utfBit = encodeInUtf8 ? 0 : (1 << 7); 143 char status = (char) (utfBit + langBytes.length); 144 145 byte[] data = Bytes.concat( 146 new byte[] { (byte) status }, 147 langBytes, 148 textBytes 149 ); 150 151 return new NdefRecord(NdefRecord.TNF_WELL_KNOWN, NdefRecord.RTD_TEXT, new byte[0], data); 152 } 153 } 154