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Java 比较两个主机名，以检查它们是否为同一主机，而不进行DNS解析。

欢马劈雪

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比较两个主机名，以检查它们是否为同一主机，而不进行DNS解析。

实例源码：

源代码：

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//package com.nowjava;
/* 
 来自 
*nowjava.com*/

import sun.net.util.IPAddressUtil;

public class Main {

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

String hostA = "nowjava.com";

String hostB = "nowjava.com";

System.out.println(ifSameHost(hostA, hostB));

}

/**

*  This method is to compare two host name

*  to check if they are the same host without DNS resolving.

*  If the host name is IP address string, e.g., '2001:1b70:82a9:6100::9'

*  the comparison supports to compare different format of same IP address.

*  If the host name is just an host name instead of IP address,

*  it just compare the String by using

*  String.equals(...)

* @param hostA

* @param hostB

* @return

*/
     /*
      from 时代Java公众号 - N o w J a  v a . c o m 
     */

public static boolean ifSameHost(String hostA, String hostB) {

boolean same = false;

if (hostA == null && hostB == null) {

return true;

}

byte[] addr1 = parseIpAddress(hostA);

byte[] addr2 = parseIpAddress(hostB);

//If this IP address string, compare the IP address

if (addr1 != null && addr2 != null) {

same = ifSameIpAddress(addr1, addr2);

}

//If this is host mame, just compare the host name string

if (!same && hostA != null)

same = hostA.equals(hostB);

return same;

}

/**

* This function parse the IP address string as a byte array

* If the IP address is IPv4 address, the byte array length is 4

* If the IP address is IPv6 address, the byte array length is 16

* If the host is not an IP address string, will return null;

* @param ipAddress

* @return if this is valid IPv4 address or IPv6 address, return byte array for the address

* otherwise return null.

* So, this method can be used to check if the ipAddress string is valid or not

public static byte[] parseIpAddress(String ipAddress) {

if (ipAddress == null)

return null;

boolean ipv6Expected = false;

if (ipAddress.charAt(0) == '[') {

// This is supposed to be an IPv6 literal

if (ipAddress.length() > 2

&& ipAddress.charAt(ipAddress.length() - 1) == ']') {

ipAddress = ipAddress.substring(1, ipAddress.length() - 1);

ipv6Expected = true;

} else {

// This was supposed to be a IPv6 address, but it's not!

//throw new UnknownHostException(host + ": invalid IPv6 address");

return null;

}

// if host is an IP address, we won't do further lookup

if (Character.digit(ipAddress.charAt(0), 16) != -1

|| (ipAddress.charAt(0) == ':')) {

byte[] addressBytes = null;

//            int numericZone = -1;

//            String ifname = null;

// see if it is IPv4 address

addressBytes = IPAddressUtil.textToNumericFormatV4(ipAddress);

if (addressBytes == null) {

addressBytes = IPAddressUtil

.textToNumericFormatV6(ipAddress);

} else if (ipv6Expected) {

// Means an IPv4 litteral between brackets!

//throw new UnknownHostException("["+host+"]");

return null;

}

return addressBytes;

} else if (ipv6Expected) {

// We were expecting an IPv6 Litteral, but got something else

//throw new UnknownHostException("["+host+"]");

return null;

}

return null;

}

/**

* Compare two IP address byte array, the length must be 4 or 16.

* @param address1

* @param address2

* @return

private static boolean ifSameIpAddress(byte[] address1, byte[] address2) {

if (address1 == null && address2 == null)

return true;

if (address1 != null && address2 != null

&& address1.length == address2.length) {

//this IPv4 address

if (address1.length == 4) {
/**代码未完, 请加载全部代码(NowJava.com).**/

​x
 
​
​
//package com.nowjava;
/* 
 来自 
*nowjava.com*/
​
import sun.net.util.IPAddressUtil;
​
​
public class Main {
​
    public static void main(String[] argv) throws Exception {
​
        String hostA = "nowjava.com";
​
        String hostB = "nowjava.com";
​
        System.out.println(ifSameHost(hostA, hostB));
​
    }
​
​
    /**
​
     *  This method is to compare two host name
​
     *  to check if they are the same host without DNS resolving.
​
     *  If the host name is IP address string, e.g., '2001:1b70:82a9:6100::9'
​
     *  the comparison supports to compare different format of same IP address.
​
     *
​
     *  If the host name is just an host name instead of IP address,
​
     *  it just compare the String by using
​
     *  String.equals(...)
​
     *
​
     * @param hostA
​
     * @param hostB
​
     * @return
​
     */
     /*
      from 时代Java公众号 - N o w J a  v a . c o m 
     */
​
    public static boolean ifSameHost(String hostA, String hostB) {
​
​
        boolean same = false;
​
​
        if (hostA == null && hostB == null) {
​
            return true;
​
        }
​
​
        byte[] addr1 = parseIpAddress(hostA);
​
​
        byte[] addr2 = parseIpAddress(hostB);
​
​
        //If this IP address string, compare the IP address
​
        if (addr1 != null && addr2 != null) {
​
            same = ifSameIpAddress(addr1, addr2);
​
        }
​
​
        //If this is host mame, just compare the host name string
​
        if (!same && hostA != null)
​
            same = hostA.equals(hostB);
​
​
        return same;
​
    }
​
​
    /**
​
     * This function parse the IP address string as a byte array
​
     * If the IP address is IPv4 address, the byte array length is 4
​
     * If the IP address is IPv6 address, the byte array length is 16
​
     * If the host is not an IP address string, will return null;
​
     * @param ipAddress
​
     * @return if this is valid IPv4 address or IPv6 address, return byte array for the address
​
     * otherwise return null.
​
     * So, this method can be used to check if the ipAddress string is valid or not
​
     */
​
    public static byte[] parseIpAddress(String ipAddress) {
​
        if (ipAddress == null)
​
            return null;
​
        boolean ipv6Expected = false;
​
        if (ipAddress.charAt(0) == '[') {
​
            // This is supposed to be an IPv6 literal
​
            if (ipAddress.length() > 2
​
                    && ipAddress.charAt(ipAddress.length() - 1) == ']') {
​
                ipAddress = ipAddress.substring(1, ipAddress.length() - 1);
​
                ipv6Expected = true;
​
            } else {
​
                // This was supposed to be a IPv6 address, but it's not!
​
                //throw new UnknownHostException(host + ": invalid IPv6 address");
​
                return null;
​
            }
​
        }
​
​
        // if host is an IP address, we won't do further lookup
​
        if (Character.digit(ipAddress.charAt(0), 16) != -1
​
                || (ipAddress.charAt(0) == ':')) {
​
            byte[] addressBytes = null;
​
            //            int numericZone = -1;
​
            //            String ifname = null;
​
​
            // see if it is IPv4 address
​
            addressBytes = IPAddressUtil.textToNumericFormatV4(ipAddress);
​
            if (addressBytes == null) {
​
                addressBytes = IPAddressUtil
​
                        .textToNumericFormatV6(ipAddress);
​
            } else if (ipv6Expected) {
​
                // Means an IPv4 litteral between brackets!
​
                //throw new UnknownHostException("["+host+"]");
​
                return null;
​
            }
​
            return addressBytes;
​
​
        } else if (ipv6Expected) {
​
            // We were expecting an IPv6 Litteral, but got something else
​
            //throw new UnknownHostException("["+host+"]");
​
            return null;
​
        }
​
​
        return null;
​
    }
​
​
    /**
​
     * Compare two IP address byte array, the length must be 4 or 16.
​
     * @param address1
​
     * @param address2
​
     * @return
​
     */
​
    private static boolean ifSameIpAddress(byte[] address1, byte[] address2) {
​
        if (address1 == null && address2 == null)
​
            return true;
​
​
        if (address1 != null && address2 != null
​
                && address1.length == address2.length) {
​
            //this IPv4 address
​
            if (address1.length == 4) {
/**代码未完, 请加载全部代码(NowJava.com).**/