如何用 Java 获取系统 IP

import java.net.*;

public class Test6 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		InetAddress ia=null;
		try {
			ia=ia.getLocalHost();
			
			String localname=ia.getHostName();
			String localip=ia.getHostAddress();
			System.out.println("本机名称是："+ localname);
			System.out.println("本机的ip是 ："+localip);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}

public static InetAddress getSystemLocalIp() throws UnknownHostException{
InetAddress inet=null;
String osname=getSystemOSName();
try {
//针对window系统
if(osname.equalsIgnoreCase("Windows XP")){
inet=getWinLocalIp();
//针对linux系统
}else if(osname.equalsIgnoreCase("Linux")){
inet=getUnixLocalIp();
}
if(null==inet){
throw new UnknownHostException("主机的ip地址未知");
}
}catch (SocketException e) {
logger.error("获取本机ip错误"+e.getMessage());
throw new UnknownHostException("获取本机ip错误"+e.getMessage());
}
return inet;
}