https://source.android.com/ 
/*
 * 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.Tag;
import android.os.Bundle;
import android.os.RemoteException;

import java.io.IOException;


Provides access to NFC-V (ISO 15693) properties and I/O operations on a Tag. 
Acquire a NfcV object using get. 
The primary NFC-V 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-V (ISO 15693) properties and I/O operations on a {@link Tag}.
 *
 * <p>Acquire a {@link NfcV} object using {@link #get}.
 * <p>The primary NFC-V 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 NfcV extends BasicTagTechnology {
    
@hide
/** @hide */
    public static final String EXTRA_RESP_FLAGS = "respflags";

    
@hide
/** @hide */
    public static final String EXTRA_DSFID = "dsfid";

    private byte mRespFlags;
    private byte mDsfId;

    
Get an instance of NfcV for the given tag. 
Returns null if NfcV was not enumerated in Tag.getTechList. This indicates the tag does not support NFC-V. 
Does not cause any RF activity and does not block.

Params:
  • tag – an NFC-V compatible tag
Returns:NFC-V object
/**
     * Get an instance of {@link NfcV} for the given tag.
     * <p>Returns null if {@link NfcV} was not enumerated in {@link Tag#getTechList}.
     * This indicates the tag does not support NFC-V.
     * <p>Does not cause any RF activity and does not block.
     *
     * @param tag an NFC-V compatible tag
     * @return NFC-V object
     */
    public static NfcV get(Tag tag) {
        if (!tag.hasTech(TagTechnology.NFC_V)) return null;
        try {
            return new NfcV(tag);
        } catch (RemoteException e) {
            return null;
        }
    }

    
@hide
/** @hide */
    public NfcV(Tag tag) throws RemoteException {
        super(tag, TagTechnology.NFC_V);
        Bundle extras = tag.getTechExtras(TagTechnology.NFC_V);
        mRespFlags = extras.getByte(EXTRA_RESP_FLAGS);
        mDsfId = extras.getByte(EXTRA_DSFID);
    }

    
Return the Response Flag bytes from tag discovery.

Does not cause any RF activity and does not block.

Returns:Response Flag bytes
/**
     * Return the Response Flag bytes from tag discovery.
     *
     * <p>Does not cause any RF activity and does not block.
     *
     * @return Response Flag bytes
     */
    public byte getResponseFlags() {
        return mRespFlags;
    }

    
Return the DSF ID bytes from tag discovery.

Does not cause any RF activity and does not block.

Returns:DSF ID bytes
/**
     * Return the DSF ID bytes from tag discovery.
     *
     * <p>Does not cause any RF activity and does not block.
     *
     * @return DSF ID bytes
     */
    public byte getDsfId() {
        return mDsfId;
    }

    
Send raw NFC-V commands to the tag and receive the response.

Applications must not append the CRC to the payload,
it will be automatically calculated. The application does
provide FLAGS, CMD and PARAMETER bytes.

Use getMaxTransceiveLength to retrieve the maximum amount 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-V commands to the tag and receive the response.
     *
     * <p>Applications must not append the CRC to the payload,
     * it will be automatically calculated. The application does
     * provide FLAGS, CMD and PARAMETER bytes.
     *
     * <p>Use {@link #getMaxTransceiveLength} to retrieve the maximum amount 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();
    }
}