Java获取系统的网卡IP

import java.net.Inet4Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.util.Enumeration;

/**
 * 
 * 
 */
public class NetUtil {
    public static String INTRANET_IP = getIntranetIp(); // 内网IP
    public static String INTERNET_IP = getInternetIp(); // 外网IP

    private NetUtil(){}

    /**
     * 获得内网IP
     * @return 内网IP
     */
    private static String getIntranetIp(){
        try{
            return InetAddress.getLocalHost().getHostAddress();
        } catch(Exception e){
            throw new RuntimeException(e);
        }
    }

    /**
     * 获得外网IP
     * @return 外网IP
     */
    private static String getInternetIp(){
        try{
            Enumeration networks = NetworkInterface.getNetworkInterfaces();
            InetAddress ip = null;
            Enumeration addrs;
            while (networks.hasMoreElements())
            {
                addrs = networks.nextElement().getInetAddresses();
                while (addrs.hasMoreElements())
                {
                    ip = addrs.nextElement();
                    if (ip != null
                            && ip instanceof Inet4Address
                            && ip.isSiteLocalAddress()
                            && !ip.getHostAddress().equals(INTRANET_IP))
                    {
                        return ip.getHostAddress();
                    }
                }
            }

            // 如果没有外网IP，就返回内网IP
            return INTRANET_IP;
        } catch(Exception e){
            throw new RuntimeException(e);
        }
    }

    /**
     * 获得指定网卡IP
     * @return IP
     */
    public static String getInternetIp(String type){
        try{
            Enumeration networks = NetworkInterface.getNetworkInterfaces();
            while (networks.hasMoreElements()){
            	NetworkInterface ni = (NetworkInterface) networks.nextElement();  
                if (!ni.getName().equals(type)) {  
                    continue;  
                } else {  
                    Enumeration e2 = ni.getInetAddresses();  
                    while (e2.hasMoreElements()) {  
                        InetAddress ia = (InetAddress) e2.nextElement();  
                        if (ia instanceof Inet6Address)
                            continue;  
                        return ia.getHostAddress();  
                    }  
                }
            }
            // 如果没有外网IP，就返回内网IP
            return INTRANET_IP;
        } catch(Exception e){
            throw new RuntimeException(e);
        }
    }
}