Java获得系统的外网IP

关于如何获得系统外网IP？在网上找了好久，大多数解决方案都没法直接用，所以今天和大家分享一段获得外网IP的代码！

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

/**
 * 系统工具类，用于获取系统相关信息
 * Created by kagome.
 */
public class CustomSystemUtil {
    public static String INTRANET_IP = getIntranetIp(); // 内网IP
    public static String INTERNET_IP = getInternetIp(); // 外网IP

    private CustomSystemUtil(){}

    /**
     * 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<NetworkInterface> networks = NetworkInterface.getNetworkInterfaces();
            InetAddress ip = null;
            Enumeration<InetAddress> 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);
        }
    }
}