Java网络编程从入门到精通（10）：Inet4Address类和Inet6Address类

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="ProgId" content="Word.Document"> <meta name="Generator" content="Microsoft Word 11"> <meta name="Originator" content="Microsoft Word 11"> <link rel="File-List" href="file:///C:%5CDOCUME%7E1%5CADMINI%7E1%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"> <!--[if gte mso 9]><xml> Normal 0 7.8 磅 0 2 false false false MicrosoftInternetExplorer4 </xml><![endif]--><!--[if gte mso 9]><![endif]--><style> <!-- /* Font Definitions */ &#64;font-face {font-family:宋体; panose-1:2 1 6 0 3 1 1 1 1 1;} &#64;font-face {font-family:""&#64;宋体"; panose-1:2 1 6 0 3 1 1 1 1 1;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; text-align:justify; text-justify:inter-ideograph; font-size:10.5pt; font-family:"Times New Roman";} /* Page Definitions */ &#64;page {} &#64;page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt;} div.Section1 {page:Section1;} --> </style> <!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable { mso-style-parent:""; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} </style> <![endif]-->

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上一篇：Java网络编程从入门到精通 （9）：使用isXxx方法判断地址类型

为了区分IPv4和IPv6地址，Java提供了两个类：Inet4Address和Inet6Address，它们都是InetAddress类的子类，这两个类的定义如下：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> public final class Inet4Address extends InetAddress
public final class Inet6Address extends InetAddress

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 11"><meta name="Originator" content="Microsoft Word 11"><link rel="File-List" href="file:///C:%5CDOCUME%7E1%5CADMINI%7E1%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"><!--[if gte mso 9]><xml> Normal 0 7.8 磅 0 2 false false false MicrosoftInternetExplorer4 </xml><![endif]--><!--[if gte mso 9]><![endif]--><style> <!-- /* Font Definitions */ &#64;font-face {font-family:宋体; panose-1:2 1 6 0 3 1 1 1 1 1;} &#64;font-face {font-family:""&#64;宋体"; panose-1:2 1 6 0 3 1 1 1 1 1;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; text-align:justify; text-justify:inter-ideograph; font-size:10.5pt; font-family:"Times New Roman";} /* Page Definitions */ &#64;page {} &#64;page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt;} div.Section1 {page:Section1;} --> </style><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable { mso-style-parent:""; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} </style> <![endif]-->

这两个类分别按着IPv4和IPv6的规则实现了InetAddress类中的public方法。它们所不同的是Inet6Address类比Inet4Address类多了一个方法：isIPv4CompatibleAddress，这个方法用来判断一个IPv6地址是否和IPv4地址兼容。和IPv4兼容的IPv6地址除了最后四个字节有值名，其他的字节都是0，如0:0:0:0:0:0.192.168.18.10、::ABCD:FAFA都是和IPv4兼容的IPv6地址。

当使用InetAddress类的四个静态方法创建InetAddress对象后，可以通过getAddress返回的byte数组来判断这个IP地址是IPv4还是IPv6地址（byte数组长度为4就是IPv4地址，byte数组长度为16就是IPv6地址），也可以将instanceof来确定InetAddress对象是它的哪个子类的实例。下面的代码演示了如何判断一个IP地址是IPv4还是IPv6地址：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> package mynet;

import java.net. * ;

public class MyIP
{
public static void main(String[]args) throws Exception
{
if (args.length == 0 )
return ;
InetAddressaddress = InetAddress.getByName(args[ 0 ]);
System.out.println( " IP: " + address.getHostAddress());
switch (address.getAddress().length)
{
case 4 :
System.out.println( " 根据byte数组长度判断这个IP地址是IPv4地址! " );
break ;
case 16 :
System.out.println( " 根据byte数组长度判断这个IP地址是IPv6地址! " );
break ;
}
if (address instanceof Inet4Address)
System.out.println( " 使用instanceof判断这个IP地址是IPv4地址! " );
else if (address instanceof Inet6Address)
System.out.println( " 使用instanceof判断这个IP地址是IPv6地址! " );
}
}

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 11"><meta name="Originator" content="Microsoft Word 11"><link rel="File-List" href="file:///C:%5CDOCUME%7E1%5CADMINI%7E1%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"><!--[if gte mso 9]><xml> Normal 0 7.8 磅 0 2 false false false MicrosoftInternetExplorer4 </xml><![endif]--><!--[if gte mso 9]><![endif]--><!--[if !mso]> <style> st1":*{behavior:url(#ieooui) } </style> <![endif]--><style> <!-- /* Font Definitions */ &#64;font-face {font-family:Wingdings; panose-1:5 0 0 0 0 0 0 0 0 0;} &#64;font-face {font-family:宋体; panose-1:2 1 6 0 3 1 1 1 1 1;} &#64;font-face {font-family:""&#64;宋体"; panose-1:2 1 6 0 3 1 1 1 1 1;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; text-align:justify; text-justify:inter-ideograph; font-size:10.5pt; font-family:"Times New Roman";} /* Page Definitions */ &#64;page {} &#64;page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt;} div.Section1 {page:Section1;} /* List Definitions */ &#64;list l0 {} &#64;list l0:level1 { margin-left:42.75pt; text-indent:-21.0pt; font-family:Wingdings;} ol {margin-bottom:0cm;} ul {margin-bottom:0cm;} --> </style><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable { mso-style-parent:""; font-size:10.0pt; font-family:"Times New Roman";} </style> <![endif]-->测试1

执行如下命令：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> javamynet.MyIPwww.csdn.net

运行结果：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> IP: 211.100.26.122
根据byte数组长度判断这个IP地址是IPv4地址!
使用instanceof判断这个IP地址是IPv4地址!

测试2

执行如下命令：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> javamynet.MyIPwww.neu6.edu.cn

运行结果：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> IP: 2001 :da8: 9000 :b255: 200 :e8ff:feb0:5c5e
根据byte数组长度判断这个IP地址是IPv6地址!
使用instanceof判断这个IP地址是IPv6地址!

下一篇： Java网络编程从入门到精通（11）：使用NetworkInterface类获得网络接口信息

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