Java获取客户端真实IP地址过程解析

　　request.getHeader("x-forwarded-for") : 10.47.103.13,4.2.2.2,10.96.112.230
　　request.getHeader("X-Real-IP") : 10.47.103.13
　　request.getRemoteAddr():10.96.112.230

/**
 * 获取客户端的IP地址<br/>
 * 注意本地测试访问项目地址时，浏览器请求不要用 localhost，请用本机IP；否则，取不到 IP
 *
 * @author east7
 * @date 2019年12月03日
 * @return String 真实IP地址
 */
public static String getClientIpAddress(HttpServletRequest request) {
  // 获取请求主机IP地址,如果通过代理进来，则透过防火墙获取真实IP地址
  String headerName = "x-forwarded-for";
  String ip = request.getHeader(headerName);
  if (null != ip && ip.length() != 0 && !"unknown".equalsIgnoreCase(ip)) {
    // 多次反向代理后会有多个IP值，第一个IP才是真实IP,它们按照英文逗号','分割
    if (ip.indexOf(",") != -1) {
      ip = ip.split(",")[0];
    }
  }
  if (checkIp(ip)) {
    headerName = "Proxy-Client-IP";
    ip = request.getHeader(headerName);
  }
  if (checkIp(ip)) {
    headerName = "WL-Proxy-Client-IP";
    ip = request.getHeader(headerName);
  }
  if (checkIp(ip)) {
    headerName = "HTTP_CLIENT_IP";
    ip = request.getHeader(headerName);
  }
  if (checkIp(ip)) {
    headerName = "HTTP_X_FORWARDED_FOR";
    ip = request.getHeader(headerName);
  }
  if (checkIp(ip)) {
    headerName = "X-Real-IP";
    ip = request.getHeader(headerName);
  }
  if (checkIp(ip)) {
    headerName = "remote addr";
    ip = request.getRemoteAddr();
    // 127.0.0.1 ipv4, 0:0:0:0:0:0:0:1 ipv6
    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();
      } catch (UnknownHostException e) {
        e.printStackTrace();
      }
      ip = inet.getHostAddress();
    }
  }
  logger.info("getClientIp IP is " + ip + ", headerName = " + headerName);
  return ip;
}
private static boolean checkIp(String ip) {
  if (null == ip || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
    return true;
  }
  return false;
}