Java tutorial
/* * Copyright (C) 2010 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package android.nfc.tech; import android.nfc.ErrorCodes; import android.nfc.Tag; import android.os.Bundle; import android.os.RemoteException; import android.util.Log; import java.io.IOException; /** * Provides access to ISO-DEP (ISO 14443-4) properties and I/O operations on a {@link Tag}. * * <p>Acquire an {@link IsoDep} object using {@link #get}. * <p>The primary ISO-DEP I/O operation is {@link #transceive}. Applications must * implement their own protocol stack on top of {@link #transceive}. * <p>Tags that enumerate the {@link IsoDep} technology in {@link Tag#getTechList} * will also enumerate * {@link NfcA} or {@link NfcB} (since IsoDep builds on top of either of these). * * <p class="note"><strong>Note:</strong> Methods that perform I/O operations * require the {@link android.Manifest.permission#NFC} permission. */ public final class IsoDep extends BasicTagTechnology { private static final String TAG = "NFC"; /** @hide */ public static final String EXTRA_HI_LAYER_RESP = "hiresp"; /** @hide */ public static final String EXTRA_HIST_BYTES = "histbytes"; private byte[] mHiLayerResponse = null; private byte[] mHistBytes = null; /** * Get an instance of {@link IsoDep} for the given tag. * <p>Does not cause any RF activity and does not block. * <p>Returns null if {@link IsoDep} was not enumerated in {@link Tag#getTechList}. * This indicates the tag does not support ISO-DEP. * * @param tag an ISO-DEP compatible tag * @return ISO-DEP object */ public static IsoDep get(Tag tag) { if (!tag.hasTech(TagTechnology.ISO_DEP)) return null; try { return new IsoDep(tag); } catch (RemoteException e) { return null; } } /** @hide */ public IsoDep(Tag tag) throws RemoteException { super(tag, TagTechnology.ISO_DEP); Bundle extras = tag.getTechExtras(TagTechnology.ISO_DEP); if (extras != null) { mHiLayerResponse = extras.getByteArray(EXTRA_HI_LAYER_RESP); mHistBytes = extras.getByteArray(EXTRA_HIST_BYTES); } } /** * Set the timeout of {@link #transceive} in milliseconds. * <p>The timeout only applies to ISO-DEP {@link #transceive}, and is * reset to a default value when {@link #close} is called. * <p>Setting a longer timeout may be useful when performing * transactions that require a long processing time on the tag * such as key generation. * * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission. * * @param timeout timeout value in milliseconds */ public void setTimeout(int timeout) { try { int err = mTag.getTagService().setTimeout(TagTechnology.ISO_DEP, timeout); if (err != ErrorCodes.SUCCESS) { throw new IllegalArgumentException("The supplied timeout is not valid"); } } catch (RemoteException e) { Log.e(TAG, "NFC service dead", e); } } /** * Get the current timeout for {@link #transceive} in milliseconds. * * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission. * * @return timeout value in milliseconds */ public int getTimeout() { try { return mTag.getTagService().getTimeout(TagTechnology.ISO_DEP); } catch (RemoteException e) { Log.e(TAG, "NFC service dead", e); return 0; } } /** * Return the ISO-DEP historical bytes for {@link NfcA} tags. * <p>Does not cause any RF activity and does not block. * <p>The historical bytes can be used to help identify a tag. They are present * only on {@link IsoDep} tags that are based on {@link NfcA} RF technology. * If this tag is not {@link NfcA} then null is returned. * <p>In ISO 14443-4 terminology, the historical bytes are a subset of the RATS * response. * * @return ISO-DEP historical bytes, or null if this is not a {@link NfcA} tag */ public byte[] getHistoricalBytes() { return mHistBytes; } /** * Return the higher layer response bytes for {@link NfcB} tags. * <p>Does not cause any RF activity and does not block. * <p>The higher layer response bytes can be used to help identify a tag. * They are present only on {@link IsoDep} tags that are based on {@link NfcB} * RF technology. If this tag is not {@link NfcB} then null is returned. * <p>In ISO 14443-4 terminology, the higher layer bytes are a subset of the * ATTRIB response. * * @return ISO-DEP historical bytes, or null if this is not a {@link NfcB} tag */ public byte[] getHiLayerResponse() { return mHiLayerResponse; } /** * Send raw ISO-DEP data to the tag and receive the response. * * <p>Applications must only send the INF payload, and not the start of frame and * end of frame indicators. Applications do not need to fragment the payload, it * will be automatically fragmented and defragmented by {@link #transceive} if * it exceeds FSD/FSC limits. * * <p>Use {@link #getMaxTransceiveLength} to retrieve the maximum number of bytes * that can be sent with {@link #transceive}. * * <p>This is an I/O operation and will block until complete. It must * not be called from the main application thread. A blocked call will be canceled with * {@link IOException} if {@link #close} is called from another thread. * * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission. * * @param data command bytes to send, must not be null * @return response bytes received, will not be null * @throws TagLostException if the tag leaves the field * @throws IOException if there is an I/O failure, or this operation is canceled */ public byte[] transceive(byte[] data) throws IOException { return transceive(data, true); } /** * Return the maximum number of bytes that can be sent with {@link #transceive}. * @return the maximum number of bytes that can be sent with {@link #transceive}. */ public int getMaxTransceiveLength() { return getMaxTransceiveLengthInternal(); } /** * <p>Standard APDUs have a 1-byte length field, allowing a maximum of * 255 payload bytes, which results in a maximum APDU length of 261 bytes. * * <p>Extended length APDUs have a 3-byte length field, allowing 65535 * payload bytes. * * <p>Some NFC adapters, like the one used in the Nexus S and the Galaxy Nexus * do not support extended length APDUs. They are expected to be well-supported * in the future though. Use this method to check for extended length APDU * support. * * @return whether the NFC adapter on this device supports extended length APDUs. */ public boolean isExtendedLengthApduSupported() { try { return mTag.getTagService().getExtendedLengthApdusSupported(); } catch (RemoteException e) { Log.e(TAG, "NFC service dead", e); return false; } } }