/*
* 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 NFC-A (ISO 14443-3A) properties and I/O operations on a Tag. Acquire a NfcA object using get.
The primary NFC-A I/O operation is transceive. Applications must implement their own protocol stack on top of transceive.
Note: Methods that perform I/O operations require the NFC.NFC permission.
/**
* Provides access to NFC-A (ISO 14443-3A) properties and I/O operations on a {@link Tag}.
*
* <p>Acquire a {@link NfcA} object using {@link #get}.
* <p>The primary NFC-A I/O operation is {@link #transceive}. Applications must
* implement their own protocol stack on top of {@link #transceive}.
*
* <p class="note"><strong>Note:</strong> Methods that perform I/O operations
* require the {@link android.Manifest.permission#NFC} permission.
*/
public final class NfcA extends BasicTagTechnology {
private static final String TAG = "NFC";
@hide
/** @hide */
public static final String EXTRA_SAK = "sak";
@hide
/** @hide */
public static final String EXTRA_ATQA = "atqa";
private short mSak;
private byte[] mAtqa;
Get an instance of NfcA for the given tag. Returns null if NfcA was not enumerated in Tag.getTechList. This indicates the tag does not support NFC-A.
Does not cause any RF activity and does not block.
Params: - tag – an NFC-A compatible tag
Returns: NFC-A object
/**
* Get an instance of {@link NfcA} for the given tag.
* <p>Returns null if {@link NfcA} was not enumerated in {@link Tag#getTechList}.
* This indicates the tag does not support NFC-A.
* <p>Does not cause any RF activity and does not block.
*
* @param tag an NFC-A compatible tag
* @return NFC-A object
*/
public static NfcA get(Tag tag) {
if (!tag.hasTech(TagTechnology.NFC_A)) return null;
try {
return new NfcA(tag);
} catch (RemoteException e) {
return null;
}
}
@hide
/** @hide */
public NfcA(Tag tag) throws RemoteException {
super(tag, TagTechnology.NFC_A);
Bundle extras = tag.getTechExtras(TagTechnology.NFC_A);
mSak = extras.getShort(EXTRA_SAK);
mAtqa = extras.getByteArray(EXTRA_ATQA);
}
Return the ATQA/SENS_RES bytes from tag discovery.
Does not cause any RF activity and does not block.
Returns: ATQA/SENS_RES bytes
/**
* Return the ATQA/SENS_RES bytes from tag discovery.
*
* <p>Does not cause any RF activity and does not block.
*
* @return ATQA/SENS_RES bytes
*/
public byte[] getAtqa() {
return mAtqa;
}
Return the SAK/SEL_RES bytes from tag discovery.
Does not cause any RF activity and does not block.
Returns: SAK bytes
/**
* Return the SAK/SEL_RES bytes from tag discovery.
*
* <p>Does not cause any RF activity and does not block.
*
* @return SAK bytes
*/
public short getSak() {
return mSak;
}
Send raw NFC-A commands to the tag and receive the response.
Applications must not append the EoD (CRC) to the payload,
it will be automatically calculated.
Applications must only send commands that are complete bytes,
for example a SENS_REQ is not possible (these are used to
manage tag polling and initialization).
Use getMaxTransceiveLength to retrieve the maximum number of bytes that can be sent with transceive.
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 IOException if BasicTagTechnology.close is called from another thread.
Requires the NFC.NFC permission.
Params: - data – bytes to send
Throws: - TagLostException – if the tag leaves the field
- IOException – if there is an I/O failure, or this operation is canceled
Returns: bytes received in response
/**
* Send raw NFC-A commands to the tag and receive the response.
*
* <p>Applications must not append the EoD (CRC) to the payload,
* it will be automatically calculated.
* <p>Applications must only send commands that are complete bytes,
* for example a SENS_REQ is not possible (these are used to
* manage tag polling and initialization).
*
* <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 bytes to send
* @return bytes received in response
* @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 transceive. Returns: the maximum number of bytes that can be sent with transceive.
/**
* 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();
}
Set the transceive timeout in milliseconds. The timeout only applies to transceive on this object, and is reset to a default value when BasicTagTechnology.close is called.
Setting a longer timeout may be useful when performing
transactions that require a long processing time on the tag
such as key generation.
Requires the NFC.NFC permission.
Params: - timeout – timeout value in milliseconds
/**
* Set the {@link #transceive} timeout in milliseconds.
*
* <p>The timeout only applies to {@link #transceive} on this object,
* 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.NFC_A, 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 transceive timeout in milliseconds. Requires the NFC.NFC permission.
Returns: timeout value in milliseconds
/**
* Get the current {@link #transceive} timeout 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.NFC_A);
} catch (RemoteException e) {
Log.e(TAG, "NFC service dead", e);
return 0;
}
}
}