NdefRecord.java revision 590b73bc5b8e5f7b59bff1d9264a52388a5162e6 
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
17package android.nfc;
18
19import android.os.Parcel;
20import android.os.Parcelable;
21
22import java.lang.UnsupportedOperationException;
23
24/**
25 * NDEF Record data.
26 * <p>
27 * Immutable data class. An NDEF record always contains
28 * <ul>
29 * <li>3-bit TNF field
30 * <li>Variable length type
31 * <li>Variable length ID
32 * <li>Variable length payload
33 * </ul>
34 * The TNF (Type Name Format) field indicates how to interpret the type field.
35 * <p>
36 * This class represents a logical (unchunked) NDEF record. The underlying
37 * representation may be chunked across several NDEF records when the payload is
38 * large.
39 */
40public class NdefRecord implements Parcelable {
41    /**
42     * Indicates no type, id, or payload is associated with this NDEF Record.
43     * <p>
44     * Type, id and payload fields must all be empty to be a valid TNF_EMPTY
45     * record.
46     */
47    public static final short TNF_EMPTY = 0x00;
48
49    /**
50     * Indicates the type field uses the RTD type name format.
51     * <p>
52     * Use this TNF with RTD types such as RTD_TEXT, RTD_URI.
53     */
54    public static final short TNF_WELL_KNOWN = 0x01;
55
56    /**
57     * Indicates the type field contains a value that follows the media-type BNF
58     * construct defined by RFC 2046.
59     */
60    public static final short TNF_MIME_MEDIA = 0x02;
61
62    /**
63     * Indicates the type field contains a value that follows the absolute-URI
64     * BNF construct defined by RFC 3986.
65     */
66    public static final short TNF_ABSOLUTE_URI = 0x03;
67
68    /**
69     * Indicates the type field contains a value that follows the RTD external
70     * name specification.
71     * <p>
72     * Note this TNF should not be used with RTD_TEXT or RTD_URI constants.
73     * Those are well known RTD constants, not external RTD constants.
74     */
75    public static final short TNF_EXTERNAL_TYPE = 0x04;
76
77    /**
78     * Indicates the payload type is unknown.
79     * <p>
80     * This is similar to the "application/octet-stream" MIME type. The payload
81     * type is not explicitly encoded within the NDEF Message.
82     * <p>
83     * The type field must be empty to be a valid TNF_UNKNOWN record.
84     */
85    public static final short TNF_UNKNOWN = 0x05;
86
87    /**
88     * Indicates the payload is an intermediate or final chunk of a chunked
89     * NDEF Record.
90     * <p>
91     * The payload type is specified in the first chunk, and subsequent chunks
92     * must use TNF_UNCHANGED with an empty type field. TNF_UNCHANGED must not
93     * be used in any other situation.
94     */
95    public static final short TNF_UNCHANGED = 0x06;
96
97    /**
98     * Reserved TNF type.
99     * <p>
100     * The NFC Forum NDEF Specification v1.0 suggests for NDEF parsers to treat this
101     * value like TNF_UNKNOWN.
102     * @hide
103     */
104    public static final short TNF_RESERVED = 0x07;
105
106    /**
107     * RTD Text type. For use with TNF_WELL_KNOWN.
108     */
109    public static final byte[] RTD_TEXT = {0x54};  // "T"
110
111    /**
112     * RTD URI type. For use with TNF_WELL_KNOWN.
113     */
114    public static final byte[] RTD_URI = {0x55};   // "U"
115
116    /**
117     * RTD Smart Poster type. For use with TNF_WELL_KNOWN.
118     */
119    public static final byte[] RTD_SMART_POSTER = {0x53, 0x70};  // "Sp"
120
121    /**
122     * RTD Alternative Carrier type. For use with TNF_WELL_KNOWN.
123     */
124    public static final byte[] RTD_ALTERNATIVE_CARRIER = {0x61, 0x63};  // "ac"
125
126    /**
127     * RTD Handover Carrier type. For use with TNF_WELL_KNOWN.
128     */
129    public static final byte[] RTD_HANDOVER_CARRIER = {0x48, 0x63};  // "Hc"
130
131    /**
132     * RTD Handover Request type. For use with TNF_WELL_KNOWN.
133     */
134    public static final byte[] RTD_HANDOVER_REQUEST = {0x48, 0x72};  // "Hr"
135
136    /**
137     * RTD Handover Select type. For use with TNF_WELL_KNOWN.
138     */
139    public static final byte[] RTD_HANDOVER_SELECT = {0x48, 0x73}; // "Hs"
140
141    private static final byte FLAG_MB = (byte) 0x80;
142    private static final byte FLAG_ME = (byte) 0x40;
143    private static final byte FLAG_CF = (byte) 0x20;
144    private static final byte FLAG_SR = (byte) 0x10;
145    private static final byte FLAG_IL = (byte) 0x08;
146
147    private final byte mFlags;
148    private final short mTnf;
149    private final byte[] mType;
150    private final byte[] mId;
151    private final byte[] mPayload;
152
153    /**
154     * Construct an NDEF Record.
155     * <p>
156     * Applications should not attempt to manually chunk NDEF Records - the
157     * implementation of android.nfc will automatically chunk an NDEF Record
158     * when necessary (and only present a single logical NDEF Record to the
159     * application). So applications should not use TNF_UNCHANGED.
160     *
161     * @param tnf  a 3-bit TNF constant
162     * @param type byte array, containing zero to 255 bytes, must not be null
163     * @param id   byte array, containing zero to 255 bytes, must not be null
164     * @param payload byte array, containing zero to (2 ** 32 - 1) bytes,
165     *                must not be null
166     */
167    public NdefRecord(short tnf, byte[] type, byte[] id, byte[] payload) {
168        /* check arguments */
169        if ((type == null) || (id == null) || (payload == null)) {
170            throw new IllegalArgumentException("Illegal null argument");
171        }
172
173        /* generate flag */
174        byte flags = FLAG_MB | FLAG_ME;
175
176        /* Determine if it is a short record */
177        if(payload.length < 0xFF) {
178            flags |= FLAG_SR;
179        }
180
181        /* Determine if an id is present */
182        if(id.length != 0) {
183            flags |= FLAG_IL;
184        }
185
186        mFlags = flags;
187        mTnf = tnf;
188        mType = type.clone();
189        mId = id.clone();
190        mPayload = payload.clone();
191    }
192
193    /**
194     * Construct an NDEF Record from raw bytes.
195     * <p>
196     * Validation is performed to make sure the header is valid, and that
197     * the id, type and payload sizes appear to be valid.
198     *
199     * @throws FormatException if the data is not a valid NDEF record
200     */
201    public NdefRecord(byte[] data) {
202        throw new UnsupportedOperationException();
203    }
204
205    /**
206     * Returns the 3-bit TNF.
207     * <p>
208     * TNF is the top-level type.
209     */
210    public short getTnf() {
211        return mTnf;
212    }
213
214    /**
215     * Returns the variable length Type field.
216     * <p>
217     * This should be used in conjunction with the TNF field to determine the
218     * payload format.
219     */
220    public byte[] getType() {
221        return mType.clone();
222    }
223
224    /**
225     * Returns the variable length ID.
226     */
227    public byte[] getId() {
228        return mId.clone();
229    }
230
231    /**
232     * Returns the variable length payload.
233     */
234    public byte[] getPayload() {
235        return mPayload.clone();
236    }
237
238    /**
239     * Return this NDEF Record as a byte array.
240     * @hide
241     */
242    public byte[] toByteArray() {
243        return generate(mFlags, mTnf, mType, mId, mPayload);
244    }
245
246    public int describeContents() {
247        return 0;
248    }
249
250    public void writeToParcel(Parcel dest, int flags) {
251        dest.writeInt(mTnf);
252        dest.writeInt(mType.length);
253        dest.writeByteArray(mType);
254        dest.writeInt(mId.length);
255        dest.writeByteArray(mId);
256        dest.writeInt(mPayload.length);
257        dest.writeByteArray(mPayload);
258    }
259
260    public static final Parcelable.Creator<NdefRecord> CREATOR =
261            new Parcelable.Creator<NdefRecord>() {
262        public NdefRecord createFromParcel(Parcel in) {
263            short tnf = (short)in.readInt();
264            int typeLength = in.readInt();
265            byte[] type = new byte[typeLength];
266            in.readByteArray(type);
267            int idLength = in.readInt();
268            byte[] id = new byte[idLength];
269            in.readByteArray(id);
270            int payloadLength = in.readInt();
271            byte[] payload = new byte[payloadLength];
272            in.readByteArray(payload);
273
274            return new NdefRecord(tnf, type, id, payload);
275        }
276        public NdefRecord[] newArray(int size) {
277            return new NdefRecord[size];
278        }
279    };
280
281    private native byte[] generate(short flags, short tnf, byte[] type, byte[] id, byte[] data);
282}