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 android.nfc.tech; 18 19 import android.nfc.ErrorCodes; 20 import android.nfc.Tag; 21 import android.os.Bundle; 22 import android.os.RemoteException; 23 import android.util.Log; 24 25 import 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 */ 37 public 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 */ get(Tag tag)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 */ NfcA(Tag tag)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 */ getAtqa()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 */ getSak()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>Use {@link #getMaxTransceiveLength} to retrieve the maximum number of bytes 106 * that can be sent with {@link #transceive}. 107 * 108 * <p>This is an I/O operation and will block until complete. It must 109 * not be called from the main application thread. A blocked call will be canceled with 110 * {@link IOException} if {@link #close} is called from another thread. 111 * 112 * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission. 113 * 114 * @param data bytes to send 115 * @return bytes received in response 116 * @throws TagLostException if the tag leaves the field 117 * @throws IOException if there is an I/O failure, or this operation is canceled 118 */ transceive(byte[] data)119 public byte[] transceive(byte[] data) throws IOException { 120 return transceive(data, true); 121 } 122 123 /** 124 * Return the maximum number of bytes that can be sent with {@link #transceive}. 125 * @return the maximum number of bytes that can be sent with {@link #transceive}. 126 */ getMaxTransceiveLength()127 public int getMaxTransceiveLength() { 128 return getMaxTransceiveLengthInternal(); 129 } 130 131 /** 132 * Set the {@link #transceive} timeout in milliseconds. 133 * 134 * <p>The timeout only applies to {@link #transceive} on this object, 135 * and is reset to a default value when {@link #close} is called. 136 * 137 * <p>Setting a longer timeout may be useful when performing 138 * transactions that require a long processing time on the tag 139 * such as key generation. 140 * 141 * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission. 142 * 143 * @param timeout timeout value in milliseconds 144 * @throws SecurityException if the tag object is reused after the tag has left the field 145 */ setTimeout(int timeout)146 public void setTimeout(int timeout) { 147 try { 148 int err = mTag.getTagService().setTimeout(TagTechnology.NFC_A, timeout); 149 if (err != ErrorCodes.SUCCESS) { 150 throw new IllegalArgumentException("The supplied timeout is not valid"); 151 } 152 } catch (RemoteException e) { 153 Log.e(TAG, "NFC service dead", e); 154 } 155 } 156 157 /** 158 * Get the current {@link #transceive} timeout in milliseconds. 159 * 160 * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission. 161 * 162 * @return timeout value in milliseconds 163 * @throws SecurityException if the tag object is reused after the tag has left the field 164 */ getTimeout()165 public int getTimeout() { 166 try { 167 return mTag.getTagService().getTimeout(TagTechnology.NFC_A); 168 } catch (RemoteException e) { 169 Log.e(TAG, "NFC service dead", e); 170 return 0; 171 } 172 } 173 } 174