java网络编程，InetAddress类实现IP地址的类型判断。

IPTest.java

import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.UnknownHostException;

public class IPTest {
  public static void main(String[] args) {
		InetAddress address;
		try {
			//根据网址域名查出地址
			//address=InetAddress.getLocalHost();
			address=InetAddress.getByName("www.baidu.com");
			System.out.println("IP地址："+address);
			
			String add1=address.getHostAddress();//61.135.169.125
			String add2=address.getHostName();//www.baidu.com
			byte[] addr=address.getAddress();
			
			System.out.println(add1);
			System.out.println(add2);
			
			int k=addr[0];
			if(k<0){
				k=k+256;
			}
			if(address instanceof Inet4Address){
				System.out.println("当前地址类型为IPv4地址！");
				if(k>=1&&k<=127){
					System.out.println("该地址是A类地址");
				}else if(k>=128&&k<=191){
					System.out.println("该地址是B类地址");
				}else if(k>=192&&k<=223){
					System.out.println("该地址是C类地址");
				}else if(k>=224&&k<=239){
					System.out.println("该地址是D类地址");
				}else if(k>=234&&k<=254){
					System.out.println("该地址是E类地址");
				}else{
					System.out.println("该地址非法");
				}
			}else if(address instanceof Inet6Address){
				System.out.println("根据地址类型判断，该地址是IPv6地址！");
			}else{
				System.out.println("该地址不是IPv6，也不是IPv4");
			}
			System.out.println(addr[0]);
			System.out.println(addr[1]);
			System.out.println(addr[2]);
			System.out.println(addr[3]);
			/*address = InetAddress.getLocalHost();//获取当前IP地址
			System.out.println(address);*/
		} catch (UnknownHostException e) {
			e.printStackTrace();
		}
	}
}