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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) {
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编辑于 2020-03-26 09:23:272020-03-26 09:23:27

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