从IPv4映射的IPv6地址转换

/*

 * Copyright (c) 2004, 2015, 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

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//package com.nowjava;// 来 自 时 代 J a v a 公 众 号


public class Main {

    public static void main(String[] argv) throws Exception {

        byte[] addr = new byte[] { 34, 35, 36, 37, 37, 37, 67, 68, 69 };

        System.out.println(java.util.Arrays

                .toString(convertFromIPv4MappedAddress(addr)));

    }


    private static final int INADDR4SZ = 4;

    private static final int INADDR16SZ = 16;


    public static byte[] convertFromIPv4MappedAddress(byte[] addr) {

        if (isIPv4MappedAddress(addr)) {

            byte[] newAddr = new byte[INADDR4SZ];/** 来 自 N o w J a v a . c o m - 时  代  Java**/

            System.arraycopy(addr, 12, newAddr, 0, INADDR4SZ);

            return newAddr;

        }

        return null;

    }


    /**

     * Utility routine to check if the InetAddress is an

     * IPv4 mapped IPv6 address.

     *

     * @return a <code>boolean</code> indicating if the InetAddress is

     * an IPv4 mapped IPv6 address; or false if address is IPv4 address.

     */

    private static boolean isIPv4MappedAddress(byte[] addr) {

        if (addr.length < INADDR16SZ) {

            return false;

        }

        if ((ad