java 获取客户端用户真实ip

public final static String getIpAddress(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 ip = request.getHeader("X-Forwarded-For");*/
  String ip = request.getHeader("x-forwarded-for");
  logger.info("x-forwarded-for------------------------------------:" + ip);
  if (logger.isInfoEnabled()) {
    logger.info("getIpAddress(HttpServletRequest) - X-Forwarded-For - String ip=" + ip);
  }

  if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
      ip = request.getHeader("Proxy-Client-IP");
      if (logger.isInfoEnabled()) {
        logger.info("getIpAddress(HttpServletRequest) - Proxy-Client-IP - String ip=" + ip);
      }
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
      ip = request.getHeader("WL-Proxy-Client-IP");
      if (logger.isInfoEnabled()) {
        logger.info("getIpAddress(HttpServletRequest) - WL-Proxy-Client-IP - String ip=" + ip);
      }
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
      ip = request.getHeader("HTTP_CLIENT_IP");
      if (logger.isInfoEnabled()) {
        logger.info("getIpAddress(HttpServletRequest) - HTTP_CLIENT_IP - String ip=" + ip);
      }
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
      ip = request.getHeader("HTTP_X_FORWARDED_FOR");
      if (logger.isInfoEnabled()) {
        logger.info("getIpAddress(HttpServletRequest) - HTTP_X_FORWARDED_FOR - String ip=" + ip);
      }
    }
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
      ip = request.getRemoteAddr();
      if (logger.isInfoEnabled()) {
        logger.info("getIpAddress(HttpServletRequest) - getRemoteAddr - String ip=" + ip);
      }
    }
  } else if (ip.length() > 15) {
    String[] ips = ip.split(",");
    for (int index = 0; index < ips.length; index++) {
      String strIp = (String) ips[index];
      if (!("unknown".equalsIgnoreCase(strIp))) {
        ip = strIp;
        break;
      }
    }
  }
  return ip;
}