import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.http.HttpServletRequest;
import java.net.InetAddress;
import java.net.UnknownHostException;

/**
 * IP工具类
 * @author justin.zheng
 * @date 2020/2/12 15:08
 */
public class IpUtils {

    private static Logger logger = LoggerFactory.getLogger(IpUtils.class);

    /**
     * 获取用户真实IP地址，不使用request.getRemoteAddr();的原因是有可能用户使用了代理软件方式避免真实IP地址。
     * 可是，如果通过了多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP值，究竟哪个才是真正的用户端的真实IP呢？
     * 答案是取X-Forwarded-For中第一个非unknown的有效IP字符串
     * @param request
     * @return
     */
    public static String getIpAddr(HttpServletRequest request) {
        String ip = request.getHeader("x-forwarded-for");
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_CLIENT_IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_X_FORWARDED_FOR");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
            if("127.0.0.1".equals(ip)||"0:0:0:0:0:0:0:1".equals(ip)){
                //根据网卡取本机配置的IP
                InetAddress inet=null;
                try {
                    inet = InetAddress.getLocalHost();
                    ip= inet.getHostAddress();
                } catch (UnknownHostException e) {
                    logger.error("==>getIpAddr error",e);
                }
            }
        }

        if(ip!=null&&ip.length()>0){
            //取第一个非unknown的有效IP字符串
            String[] split = ip.split(",");
            for (String s : split) {
                if(!"unknown".equalsIgnoreCase(s)){
                    ip = s;
                    break;
                }
            }
        }

        return ip;
    }


    private IpUtils() {
    }
}