NfcA.java revision 112fdf612db71a552fce063136bf2796df3b71ec 
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.tech;
18
19import android.nfc.ErrorCodes;
20import android.nfc.Tag;
21import android.os.Bundle;
22import android.os.RemoteException;
23import android.util.Log;
24
25import java.io.IOException;
26
27/**
28 * Provides access to NFC-A (ISO 14443-3A) properties and I/O operations on a {@link Tag}.
29 *
30 * <p>Acquire a {@link NfcA} object using {@link #get}.
31 * <p>The primary NFC-A I/O operation is {@link #transceive}. Applications must
32 * implement their own protocol stack on top of {@link #transceive}.
33 *
34 * <p class="note"><strong>Note:</strong> Methods that perform I/O operations
35 * require the {@link android.Manifest.permission#NFC} permission.
36 */
37public final class NfcA extends BasicTagTechnology {
38    private static final String TAG = "NFC";
39
40    /** @hide */
41    public static final String EXTRA_SAK = "sak";
42    /** @hide */
43    public static final String EXTRA_ATQA = "atqa";
44
45    private short mSak;
46    private byte[] mAtqa;
47
48    /**
49     * Get an instance of {@link NfcA} for the given tag.
50     * <p>Returns null if {@link NfcA} was not enumerated in {@link Tag#getTechList}.
51     * This indicates the tag does not support NFC-A.
52     * <p>Does not cause any RF activity and does not block.
53     *
54     * @param tag an NFC-A compatible tag
55     * @return NFC-A object
56     */
57    public static NfcA get(Tag tag) {
58        if (!tag.hasTech(TagTechnology.NFC_A)) return null;
59        try {
60            return new NfcA(tag);
61        } catch (RemoteException e) {
62            return null;
63        }
64    }
65
66    /** @hide */
67    public NfcA(Tag tag) throws RemoteException {
68        super(tag, TagTechnology.NFC_A);
69        Bundle extras = tag.getTechExtras(TagTechnology.NFC_A);
70        mSak = extras.getShort(EXTRA_SAK);
71        mAtqa = extras.getByteArray(EXTRA_ATQA);
72    }
73
74    /**
75     * Return the ATQA/SENS_RES bytes from tag discovery.
76     *
77     * <p>Does not cause any RF activity and does not block.
78     *
79     * @return ATQA/SENS_RES bytes
80     */
81    public byte[] getAtqa() {
82        return mAtqa;
83    }
84
85    /**
86     * Return the SAK/SEL_RES bytes from tag discovery.
87     *
88     * <p>Does not cause any RF activity and does not block.
89     *
90     * @return SAK bytes
91     */
92    public short getSak() {
93        return mSak;
94    }
95
96    /**
97     * Send raw NFC-A commands to the tag and receive the response.
98     *
99     * <p>Applications must not append the EoD (CRC) to the payload,
100     * it will be automatically calculated.
101     * <p>Applications must only send commands that are complete bytes,
102     * for example a SENS_REQ is not possible (these are used to
103     * manage tag polling and initialization).
104     *
105     * <p>This is an I/O operation and will block until complete. It must
106     * not be called from the main application thread. A blocked call will be canceled with
107     * {@link IOException} if {@link #close} is called from another thread.
108     *
109     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
110     *
111     * @param data bytes to send
112     * @return bytes received in response
113     * @throws TagLostException if the tag leaves the field
114     * @throws IOException if there is an I/O failure, or this operation is canceled
115     */
116    public byte[] transceive(byte[] data) throws IOException {
117        return transceive(data, true);
118    }
119
120    /**
121     * Set the timeout of {@link #transceive} in milliseconds.
122     * <p>The timeout only applies to NfcA {@link #transceive}, and is
123     * reset to a default value when {@link #close} is called.
124     * <p>Setting a longer timeout may be useful when performing
125     * transactions that require a long processing time on the tag
126     * such as key generation.
127     *
128     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
129     *
130     * @param timeout timeout value in milliseconds
131     * @hide
132     */
133    // TODO Unhide for ICS
134    public void setTimeout(int timeout) {
135        try {
136            int err = mTag.getTagService().setTimeout(TagTechnology.NFC_A, timeout);
137            if (err != ErrorCodes.SUCCESS) {
138                throw new IllegalArgumentException("The supplied timeout is not valid");
139            }
140        } catch (RemoteException e) {
141            Log.e(TAG, "NFC service dead", e);
142        }
143    }
144}
145