Java InetAddress to toAddrString(InetAddress ip)

Description

to Addr String

License

Apache License

Declaration

public static String toAddrString(InetAddress ip) 

Method Source Code

//package com.java2s;
/*//from w  w  w .  j av a  2s.com
 * Copyright 2018 The gRPC Authors
 *
 * 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.
 */

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.primitives.Ints;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.util.Arrays;

public class Main {
    private static final int IPV6_PART_COUNT = 8;

    public static String toAddrString(InetAddress ip) {
        checkNotNull(ip);
        if (ip instanceof Inet4Address) {
            // For IPv4, Java's formatting is good enough.
            return ip.getHostAddress();
        }
        checkArgument(ip instanceof Inet6Address);
        byte[] bytes = ip.getAddress();
        int[] hextets = new int[IPV6_PART_COUNT];
        for (int i = 0; i < hextets.length; i++) {
            hextets[i] = Ints.fromBytes((byte) 0, (byte) 0, bytes[2 * i], bytes[2 * i + 1]);
        }
        compressLongestRunOfZeroes(hextets);
        return hextetsToIPv6String(hextets);
    }

    private static void compressLongestRunOfZeroes(int[] hextets) {
        int bestRunStart = -1;
        int bestRunLength = -1;
        int runStart = -1;
        for (int i = 0; i < hextets.length + 1; i++) {
            if (i < hextets.length && hextets[i] == 0) {
                if (runStart < 0) {
                    runStart = i;
                }
            } else if (runStart >= 0) {
                int runLength = i - runStart;
                if (runLength > bestRunLength) {
                    bestRunStart = runStart;
                    bestRunLength = runLength;
                }
                runStart = -1;
            }
        }
        if (bestRunLength >= 2) {
            Arrays.fill(hextets, bestRunStart, bestRunStart + bestRunLength, -1);
        }
    }

    private static String hextetsToIPv6String(int[] hextets) {
        // While scanning the array, handle these state transitions:
        //   start->num => "num"     start->gap => "::"
        //   num->num   => ":num"    num->gap   => "::"
        //   gap->num   => "num"     gap->gap   => ""
        StringBuilder buf = new StringBuilder(39);
        boolean lastWasNumber = false;
        for (int i = 0; i < hextets.length; i++) {
            boolean thisIsNumber = hextets[i] >= 0;
            if (thisIsNumber) {
                if (lastWasNumber) {
                    buf.append(':');
                }
                buf.append(Integer.toHexString(hextets[i]));
            } else {
                if (i == 0 || lastWasNumber) {
                    buf.append("::");
                }
            }
            lastWasNumber = thisIsNumber;
        }
        return buf.toString();
    }
}

Related

1. InetAddressToInt(InetAddress ip)
2. inetAddressToThriftBinary(InetAddress inetAddress)
3. ipv4AddressToInt(InetAddress addr)
4. str(InetAddress address)
5. toAddressString(InetAddress ip)
6. toDotString(InetAddress ip)
7. toIntArray(InetAddress addr)
8. toIpAddrString(final InetAddress addr)
9. toLong(InetAddress addr)