JAVA 和python 多网卡情况下获取正确的IP地址

要获取内网地址，可以尝试连接到10.255.255.255:1。如果连接成功，获取本地套接字的地址信息就是当前的内网IP。

python实现：

import socket

def extract_ip():
    st = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    try:
        st.connect(('10.255.255.255', 1))
        IP = st.getsockname()[0]
    except Exception:
        IP = '127.0.0.1'
    finally:
        st.close()
    return IP

Java:

import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

/**
 * 网络工具
 * @author jqpeng
 */
public class NetUtils {

    public static void main(String[] args) throws UnknownHostException {
        InetAddress localHost = InetAddress.getLocalHost();
        System.out.println(localHost.getHostAddress());

        System.out.println("----------------下面才是正确的获取方式----------------");
        localHost = getLocalHostExactAddress();
        System.out.println(localHost.getHostAddress());
        // System.out.println(localHost.getHostName());
    }


    public static InetAddress getLocalHostExactAddress() {
        try {
            DatagramSocket socket = new DatagramSocket();
            socket.connect(InetAddress.getByName("10.255.255.255"), 1);
            InetAddress address = socket.getLocalAddress();
            socket.close();
            return address;
        } catch (UnknownHostException | SocketException e) {
            try {
                return InetAddress.getLocalHost();
            } catch (UnknownHostException ex) {
                throw new RuntimeException(ex);
            }
        }
    }

}

在java里，为了解决eureka获取client ip错误问题，可以重写InetUtils

/**
 * 自定义InetUtils，重写findFirstNonLoopbackAddress方法，解决获取IP错误
 * @author jqpeng
 */
@Slf4j
public class CustomInetUtils extends InetUtils {

    public CustomInetUtils(InetUtilsProperties properties) {
        super(properties);
        log.info(properties.toString());
        log.info("CustomInetUtils init");
    }

    @Override
    public InetAddress findFirstNonLoopbackAddress() {
        log.info("CustomInetUtils.findFirstNonLoopbackAddress");
        return NetUtils.getLocalHostExactAddress();
    }
}

用上面的类替换InetUtils ：

    @Bean
    public InetUtils inetUtils(InetUtilsProperties inetUtilsProperties){
        // 内网ip
        inetUtilsProperties.setUseOnlySiteLocalInterfaces(true);
        return new CustomInetUtils(inetUtilsProperties);
    }