Java example source code file (ResponseAPDU.java)

This example Java source code file (ResponseAPDU.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

classnotfoundexception, illegalargumentexception, responseapdu, string, util

The ResponseAPDU.java Java example source code

/*
 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package javax.smartcardio;

import java.util.Arrays;

/**
 * A response APDU as defined in ISO/IEC 7816-4. It consists of a conditional
 * body and a two byte trailer.
 * This class does not attempt to verify that the APDU encodes a semantically
 * valid response.
 *
 * <p>Instances of this class are immutable. Where data is passed in or out
 * via byte arrays, defensive cloning is performed.
 *
 * @see CommandAPDU
 * @see CardChannel#transmit CardChannel.transmit
 *
 * @since   1.6
 * @author  Andreas Sterbenz
 * @author  JSR 268 Expert Group
 */
public final class ResponseAPDU implements java.io.Serializable {

    private static final long serialVersionUID = 6962744978375594225L;

    /** @serial */
    private byte[] apdu;

    /**
     * Constructs a ResponseAPDU from a byte array containing the complete
     * APDU contents (conditional body and trailed).
     *
     * <p>Note that the byte array is cloned to protect against subsequent
     * modification.
     *
     * @param apdu the complete response APDU
     *
     * @throws NullPointerException if apdu is null
     * @throws IllegalArgumentException if apdu.length is less than 2
     */
    public ResponseAPDU(byte[] apdu) {
        apdu = apdu.clone();
        check(apdu);
        this.apdu = apdu;
    }

    private static void check(byte[] apdu) {
        if (apdu.length < 2) {
            throw new IllegalArgumentException("apdu must be at least 2 bytes long");
        }
    }

    /**
     * Returns the number of data bytes in the response body (Nr) or 0 if this
     * APDU has no body. This call is equivalent to
     * <code>getData().length.
     *
     * @return the number of data bytes in the response body or 0 if this APDU
     * has no body.
     */
    public int getNr() {
        return apdu.length - 2;
    }

    /**
     * Returns a copy of the data bytes in the response body. If this APDU as
     * no body, this method returns a byte array with a length of zero.
     *
     * @return a copy of the data bytes in the response body or the empty
     *    byte array if this APDU has no body.
     */
    public byte[] getData() {
        byte[] data = new byte[apdu.length - 2];
        System.arraycopy(apdu, 0, data, 0, data.length);
        return data;
    }

    /**
     * Returns the value of the status byte SW1 as a value between 0 and 255.
     *
     * @return the value of the status byte SW1 as a value between 0 and 255.
     */
    public int getSW1() {
        return apdu[apdu.length - 2] & 0xff;
    }

    /**
     * Returns the value of the status byte SW2 as a value between 0 and 255.
     *
     * @return the value of the status byte SW2 as a value between 0 and 255.
     */
    public int getSW2() {
        return apdu[apdu.length - 1] & 0xff;
    }

    /**
     * Returns the value of the status bytes SW1 and SW2 as a single
     * status word SW.
     * It is defined as
     * {@code (getSW1() << 8) | getSW2()}
     *
     * @return the value of the status word SW.
     */
    public int getSW() {
        return (getSW1() << 8) | getSW2();
    }

    /**
     * Returns a copy of the bytes in this APDU.
     *
     * @return a copy of the bytes in this APDU.
     */
    public byte[] getBytes() {
        return apdu.clone();
    }

    /**
     * Returns a string representation of this response APDU.
     *
     * @return a String representation of this response APDU.
     */
    public String toString() {
        return "ResponseAPDU: " + apdu.length + " bytes, SW="
            + Integer.toHexString(getSW());
    }

    /**
     * Compares the specified object with this response APDU for equality.
     * Returns true if the given object is also a ResponseAPDU and its bytes are
     * identical to the bytes in this ResponseAPDU.
     *
     * @param obj the object to be compared for equality with this response APDU
     * @return true if the specified object is equal to this response APDU
     */
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof ResponseAPDU == false) {
            return false;
        }
        ResponseAPDU other = (ResponseAPDU)obj;
        return Arrays.equals(this.apdu, other.apdu);
    }

    /**
     * Returns the hash code value for this response APDU.
     *
     * @return the hash code value for this response APDU.
     */
    public int hashCode() {
        return Arrays.hashCode(apdu);
    }

    private void readObject(java.io.ObjectInputStream in)
            throws java.io.IOException, ClassNotFoundException {
        apdu = (byte[])in.readUnshared();
        check(apdu);
    }

}